Document:

PURCHASE CONTRACT

                                     BETWEEN

                             PENN OCTANE CORPORATION

                                    "SELLER"

                                       AND

                      RIO VISTA OPERATING PARTNERSHIP L.P.

                                     "BUYER"

<PAGE>
<TABLE>
<CAPTION>
<S>                                                                       <C>
ARTICLE I   QUANTITY OF LPG . . . . . . . . . . . . . . . . . . . . . . .  4

ARTICLE II. TERM. . . . . . . . . . . . . . . . . . . . . . . . . . . . .  4

    Section 2.1  Term . . . . . . . . . . . . . . . . . . . . . . . . . .  4

    Section 2.2  Termination. . . . . . . . . . . . . . . . . . . . . . .  4

ARTICLE III PRICE . . . . . . . . . . . . . . . . . . . . . . . . . . . .  5

ARTICLE IV. TAXES . . . . . . . . . . . . . . . . . . . . . . . . . . . .  5

ARTICLE V POINT OF DELIVERY, FACILITIES AND OWNERSHIP AND
          CONTROL OF LPG. . . . . . . . . . . . . . . . . . . . . . . . .  5

    Section 5.1 Point of Delivery; Facilities . . . . . . . . . . . . . .  5

    Section 5.2 Ownership and Control of LPG. . . . . . . . . . . . . . .  5

ARTICLE VI.  DELIVERY PRESSURE. . . . . . . . . . . . . . . . . . . . . .  6

ARTICLE VII. NOTICES. . . . . . . . . . . . . . . . . . . . . . . . . . .  6

    Section 7.  Notices . . . . . . . . . . . . . . . . . . . . . . . . .  6

    Section 7.2 Change of Address . . . . . . . . . . . . . . . . . . . .  6

ARTICLE VIII. ASSIGNMENT. . . . . . . . . . . . . . . . . . . . . . . . .  6

ARTICLE IX.   GENERAL TERMS AND CONDITIONS. . . . . . . . . . . . . . . .  7
</TABLE>

                                    EXHIBITS

Exhibit A - General Terms and Conditions

<PAGE>
                                PURCHASE CONTRACT

     THIS PURCHASE CONTRACT (this "Contract") is made and entered into effective
as  of  the  1st day of October, 2004, by and between PENN OCTANE CORPORATION, a
Delaware  corporation  (hereinafter  called  "Seller"),  and RIO VISTA OPERATING
PARTNERSHIP  L.P.,  a Delaware limited partnership (hereinafter called "Buyer"):

                              W I T N E S S E T H:

     WHEREAS,  Seller  desires to sell and deliver to Buyer and Buyer desires to
purchase  and  receive  from  Seller  liquefied  petroleum  gas  ("LPG"), in the
quantities  and  upon  the  terms  and  conditions  hereinafter  set  forth;

     WHEREAS,  the  Conflicts  Committee of Rio Vista GP LLC has approved of the
terms  and  conditions  of  this  Contract;

     NOW,  THEREFORE,  in  consideration  of  the  premises,  and  of the mutual
covenants  and agreements contained herein, and the general terms and provisions
hereof,  Buyer  and  Seller  agree  as  follows:

                                   ARTICLE I.
                                 QUANTITY OF LPG
                                 ---------------

     Seller agrees to sell and deliver to Buyer and Buyer agrees to purchase and
receive from Seller a monthly volume of LPG equal to the total amount of LPG per
month  that Buyer sells or otherwise distributes using, in whole or in part, any
of  the  Contributed Assets to the extent Seller is able to supply quantities of
LPG  sufficient  for  Buyer's  needs.  Notwithstanding  anything  herein  to the
contrary,  Buyer  shall  have  no  obligation to purchase LPG from Seller in the
event  the  distribution of such LPG by Buyer to its customers would not require
the use, in whole or in part, of any of the Contributed Assets.  In addition, to
the  extent  Seller  does  not or cannot supply quantities of LPG sufficient for
Buyer's  needs,  Buyer  may  purchase LPG from other suppliers during the period
that  Seller  does not or cannot supply quantities of LPG sufficient for Buyer's
needs  without  any  obligation  to  Seller  hereunder.

                                   ARTICLE II.
                                      TERM
                                      ----

     Section  2.1  Term.  This  Contract shall be effective as of the 1st day of
October,  2004,  and, subject to the provisions of this Contract, shall continue
and  remain  in full force and effect for so long as the earlier to occur of (i)
Seller  ceases  to have the right to access the Seadrift Pipeline and (ii) Buyer
ceases  to  use, in whole or in part, any of the Contributed Assets for the sale
of  LPG.

     Section  2.2  Termination.  In  the  event  Buyer  takes  no LPG under this
Contract  for  thirty (30) consecutive Days for any reason whatsoever other than
force  majeure,  Seller  shall have the right, at its option, exercisable at any
time within fifteen (15) Days following such thirty (30) consecutive Day period,
to terminate this Contract by delivering to Buyer written notice of termination.
In the event Seller so elects to terminate this Contract, such termination shall
be

<PAGE>
effective  as  of  7:00  o'clock a.m. Central Time on the first Day of the Month
next  following  the  date  of  delivery  of such notice to Buyer, whereupon the
parties  hereto  shall  be relieved of all liabilities and obligations hereunder
except for liabilities and obligations of the parties that shall have accrued as
of  such  date  of  termination.  In  the event Seller does not or cannot supply
quantities  of LPG sufficient for Buyer's needs for thirty (30) consecutive Days
for  any reason whatsoever other than force majeure, Buyer shall have the right,
at  its  option, exercisable at any time within fifteen (15) Days following such
thirty  (30) consecutive Day period, to terminate this Contract by delivering to
Seller written notice of termination.  In the event Buyer so elects to terminate
this  Contract,  such  termination  shall  be  effective as of 7:00 o'clock a.m.
Central  Time  on the first Day of the Month next following the date of delivery
of  such notice to Seller, whereupon the parties hereto shall be relieved of all
liabilities  and obligations hereunder except for liabilities and obligations of
the  parties  that  shall  have  accrued  as  of  such  date  of  termination.

                                  ARTICLE III.
                                      PRICE
                                      -----

     Subject  to the provisions of this Contract, the amount payable by Buyer to
Seller  for  each  Gallon  of LPG purchased hereunder each Month shall equal the
Purchase  Price.

                                   ARTICLE IV.
                                      TAXES
                                      -----

     Seller  shall  pay or cause to be paid all taxes and assessments imposed on
Seller  with  respect  to  the  LPG delivered hereunder prior to its delivery to
Buyer, and Buyer shall pay or cause to be paid all taxes and assessments imposed
upon  Buyer  with respect to LPG delivered hereunder after its receipt by Buyer.
Neither  party  shall  be responsible or liable for any taxes or other statutory
charges levied or assessed against any of the facilities of the other party used
for  the  purpose  of  carrying  out  the  provisions  of  this  Contract.

                                   ARTICLE V.
         POINT OF DELIVERY, FACILITIES AND OWNERSHIP AND CONTROL OF LPG
         --------------------------------------------------------------

     Section  5.1     Point  of  Delivery; Facilities.  Seller shall deliver the
LPG to Buyer hereunder at the point at which the LPG exits the Seadrift Pipeline
and  is  delivered into Buyer's facilities at its Brownsville, Texas terminal or
any other point which employs the use of the Contributed Assets.  Buyer shall be
responsible  for arranging for Buyer or its designee, to receive delivery of LPG
sold  hereunder  to  Buyer  at the Delivery Point into Buyer's or its designee's
gathering  system.

     Section  5.2  Ownership  and  Control  of  LPG.  Title  to the LPG sold and
delivered  hereunder  shall  pass to Buyer at the Delivery Point. As between the
parties  hereto,  Seller  shall  be  in  control  and  possession of the LPG and
responsible  for  any damage or injury caused thereby until same shall have been
delivered  to  Buyer,  after  which  delivery  Buyer  shall  be  deemed to be in
exclusive  control  and  possession  thereof  and  responsible for any injury or
damage  caused  thereby.

<PAGE>
                                   ARTICLE VI.
                                DELIVERY PRESSURE
                                -----------------

     The LPG delivered or caused to be delivered hereunder by Seller to Buyer or
its  designee(s)  at  the  Delivery  Point  shall  be  delivered  at  a pressure
sufficient  to  enter  the facilities at such point of Buyer or its designee(s).

                                  ARTICLE VII.
                                     NOTICES
                                     -------

     Section  7.1     Notices.  Every  notice, consent, approval, communication,
request  or reply which is required or which may be given by either party to the
other  under  the terms of this Contract must be in writing, and may be effected
by actual delivery to the party to be notified, by depositing such notice in the
United States mail, postage prepaid, registered or certified mail, and addressed
to  the  party  to  be  notified  with return receipt requested, or by facsimile
transmission.  Every  notice  deposited in the United States mail as hereinabove
authorized  shall,  in the absence of a strike, lock-out, boycott or other labor
dispute  affecting  the  delivery  of United States mail, be effective three (3)
days  following the date on which it is so deposited.  Notice given by facsimile
transmission  shall be effective on completion and confirmation of the facsimile
transmission.  Notice  given  in any other manner shall be effective only if and
when  received  by  the  party  to  be  notified.  For  purposes  of notice, the
addresses  of  the  parties,  until changed as hereinafter provided, shall be as
follows:

     Seller       Penn Octane Corporation
                  77-530 Enfield Lane, Building D
                  Palm Desert, CA 92211
                  Attn:  Jerome B. Richter, President
                  Facsimile:  (760) 772-8588

     Buyer        Rio Vista Operating Partnership L.P.
                  820 Gessner Road, Suite 1285
                  Houston, Texas 77024
                  Attn:  General Partner
                  Facsimile:  (713) _____________

     Section  7.2     Change  of  Address.  Each  of  the parties shall have the
right,  from time to time,  to change its address, and each shall have the right
to  specify as its address any other address within the United States of America
by  delivering  to  the other party not less than ten (10) days' prior notice in
writing  of  such  new  address.

                                  ARTICLE VIII.
                                   ASSIGNMENT
                                   ----------

     All  the terms, conditions and provisions of this Contract shall be binding
upon  and  inure  to  the  benefit  of  the  parties hereto and their respective
successors  and  assigns;  provided,  however, no assignment of this Contract by
either  party  shall be effective or binding until a copy of such assignment has
been  furnished  to  the  other  party.

<PAGE>
                                   ARTICLE IX.
                          GENERAL TERMS AND CONDITIONS.
                          -----------------------------

     Annexed  hereto  as  a part hereof are General Terms and Conditions of this
Contract  which  General Terms and Conditions constitute a part of this Contract
and  the terms and provisions hereof to the same extent as if written in full in
the  body  hereof.

                         (Signatures on following page)

<PAGE>
     IN  WITNESS  WHEREOF,  the  parties  hereto  have executed this Contract in
multiple  counterparts,  each  of  which  shall be deemed an original but all of
which  constitute  one  and  the  same  instrument  as  of  the date first above
mentioned.

                                            "SELLER"

                                            PENN OCTANE CORPORATION

                                            By: /s/ Jerome B. Richter
                                               ---------------------------------
                                               Jerome B. Richter, Chief
                                               Executive Officer

                                            "BUYER"

                                            RIO VISTA OPERATING PARTNERSHIP L.P.

                                              By:   RIO VISTA OPERATING GP LLC,
                                              Its   General Partner

                                                  By:/s/ Richard Shore, Jr.
                                                     ---------------------------
                                                         Richard Shore, Jr.,
                                                         President

<PAGE>
                                    EXHIBIT A

                          GENERAL TERMS AND CONDITIONS
                          ----------------------------

                                   ARTICLE I.

                                   DEFINITIONS
                                   -----------

     1.1  For  the  purpose of this Contract, the following terms shall have the
meanings  ascribed  thereto  unless  their use in context is specifically to the
contrary:

     (a)  Day  -  That period of time consisting of twenty-four (24) consecutive
hours  beginning  at  7:00  a.m.  Central  Time.

     (b)  COGS  -  is  the average cost to Seller per Gallon of LPG on a monthly
basis of all LPG supplies obtained by Seller, including the base cost per Gallon
of LPG, costs to mix the product, premiums/discounts paid to suppliers for LPGs,
mercaptain,  testing  and  inspection  costs.

     (c)  Contributed  Assets - shall have the meaning set forth in that certain
Contribution,  Conveyance  and  Assumption  Agreement  dated  September 16, 2004
between  Seller  and  Buyer.

     (d)  ECCPL  -  the  twelve inch pipeline to which the Seller has access and
which  connects  ExxonMobil  Corporation's Viola valve station in Nueces County,
Texas  to  the  inlet  of  the  King  Ranch  Gas  Plant.

     (e)  Gallon  -  231  cubic inches or 0.133681 cubic feet of liquid at sixty
(60)  degrees  Fahrenheit  and  at the equilibrium vapor pressure of the liquid.

     (f)  Margin  Allocation  Amount - is the product of (i) the quotient of (a)
the  difference  of  Revenues  minus  COGS divided by (b) the Total LPG Gallons,
multiplied  by  (ii)  the quotient of (c) Penn Costs divided by (d) Total Costs.

     (g)  Month  - A chart accounting month commencing at 7:00 a.m. on the first
day  of  the  chart accounting month and ending at 7:00 a.m. on the first day of
the  following  chart  accounting  month.

     (h)  OPIS  -  the  Oil  Price  Information  Service.

     (i)  Penn  Costs  -  All  costs  of  Seller  on  a  per Gallon of LPG basis
associated  with  the  ownership  or  lease  and  operation of assets related to
bringing  LPG  from  suppliers  to  the  Delivery Point. These costs principally
relate  to  all variable charges for use of the ECCPL (including minimum thruput
charges),  the  Seadrift  Pipeline  (including  minimum  fixed  rental charges),
minimum  Markham  storage reservation fees, utilities, trucking costs, insurance
costs  and

                                      -8-
<PAGE>
depreciation.  Penn  Costs  shall also include all indirect selling, general and
administrative  costs  (excluding  amounts  paid  by Buyer). In determining Penn
Costs,  only cost items paid in cash or to be paid in cash plus depreciation and
amortization  excluding  interest  and income taxes, gains/losses on disposal of
assets  shall  be  included.

     (j)  Point  of  Delivery  and  Delivery  Point  -  the point of delivery as
described  in  Section  5.1  of  the  Contract.

     (k)  Purchase  Price  -  is the sum of the Margin Allocation Amount and the
Product  Price  Allocation.

     (l)  Product Price Allocation - the average monthly per Gallon price of LPG
in  accordance  with Buyer specifications (generally 90% propane and 10% butane)
based  on the price quoted for the month average of Mont Belvieu non-tet propane
per  OPIS and the month average price for Mont Belvieu non-tet normal butane per
OPIS.

     (m)  Revenues  - Total proceeds per Gallon of LPG to Buyer from the sale of
LPG  supplied  by  Seller.

     (n)  Rio  Vista  Costs  -  All  costs to Buyer on a per Gallon of LPG basis
associated  with ownership or lease and operation of assets employed by Buyer to
bring LPG supplied by Seller from the Delivery Point to Buyer's customers. These
costs  principally  relate  to  the  costs of operating the Brownsville terminal
facility,  the  US-Mexico  pipelines and the Matamoros terminal facility and any
other  asset  brought  on-line in the future which is put into operation for the
purpose  of  enhancing  or providing sales of LPG to customers from LPG supplies
provided  by  Seller.  Rio  Vista  Costs include payroll costs, rent, insurance,
utilities,  repairs and maintenance and depreciation. Rio Vista Costs shall also
include  all indirect selling, general and administrative costs (including costs
allocated  from  Seller, including costs incurred as a result of the creation of
Rio  Vista  Energy  Partners  L.P. as a publicly traded limited partnership). In
determining Rio Vista Costs, only costs items paid in cash or to be paid in cash
plus  depreciation  and  amortization  excluding  interest  and  income  taxes,
gains/losses  on  disposal  of  assets  shall  be  included.

     (o)  Seadrift Pipeline - an approximately 132 mile pipeline which is leased
by  Seller  from  the Seadrift Corporation and connects ExxonMobil Corporation's
King  Ranch  Gas  Plant in Kleberg County, Texas and Duke Energy's La Gloria Gas
Plant  in  Jim  Wells  County,  Texas  to  Buyer's  Brownsville,  Texas terminal
facility.

     (p)  Total  Costs  -  The  sum  of  the  Penn Costs and the Rio Vista Costs
calculated  on  a  monthly  basis.

     (q) Total LPG Gallons - is the total number of Gallons of LPG sold by Buyer
from  supplies  of  LPG  provided by Seller in any one month calculation period.

                                   ARTICLE II.

                                      -9-
<PAGE>
                                     QUALITY
                                     -------

          Seller  agrees  that  the  LPG  delivered  hereunder  shall  be  of
merchantable  quality  meeting  the  pressure  and  quality  specifications  of
customers  of  Buyer.  Buyer  shall  not  be obligated to purchase any LPG which
fails  to  meet  the foregoing contract quality specifications.  If LPG does not
meet  such  specifications and Buyer desires not to purchase LPG, Seller will be
given  a  15 day written notice of such intent.  Except as hereinafter expressly
provided,  Buyer  shall  be  obligated  to  purchase  all LPG tendered by Seller
hereunder,  whether  or  not  such  LPG  meets the quality specifications of any
particular  third  party purchaser or transporter, so long as such LPG meets the
foregoing  contract  quality  specifications.  Notwithstanding the foregoing, in
the  event  (a)  LPG delivered by Seller to Buyer hereunder is unmarketable and,
such  LPG,  when  blended  together with LPG from any other sources available to
Buyer  that  exceeds  the quality of Seller's LPG, for purposes of improving the
overall quality of Seller's LPG, is still unmarketable, and (b) Buyer reasonably
demonstrates  to Seller's satisfaction that Buyer has made reasonable efforts to
market  the  LPG  but  has been unable to market the LPG due specifically to the
quality  of  Seller's  LPG,  then Buyer shall be relieved from its obligation to
purchase and take the portion of Seller's LPG which is unmarketable but only for
the  period  of  time such LPG remains unmarketable.  In the event that such LPG
remains  unmarketable  for  a period of ninety (90) days, Seller's obligation to
sell  and  deliver  to  Buyer  and  Buyer's  obligation  to purchase and receive
hereunder  the  portion  of  Seller's  LPG  that is unmarketable shall cease and
Seller  shall  be  entitled to dispose of such LPG to any third party or parties
free  and  clear  of  any  claim  by  Buyer  hereunder.

                                  ARTICLE III.

                                   MEASUREMENT
                                   -----------

     3.1     The  unit  of  volume  for purposes of measurement of LPG delivered
hereunder  shall  be  one  (1) Gallon.  All fundamental constants, observations,
records  and  procedures  involved  in  the  determining and/or verifying of the
quality  and  other  characteristics  of  LPG  delivered hereunder shall, unless
otherwise  specified  herein,  be  in  accordance with the standards and methods
prescribed  in Gas Measurement Committee Report No. 3, dated April, 1955, of the
American  Gas  Association  as  now  and  from  time  to  time  amended.

     3.2 The temperature of the LPG flowing through the meter or meters shall be
assumed to be sixty (60) degrees Fahrenheit, but may be determined by continuous
use of a recording thermometer installed by Seller (if deemed necessary by Buyer
and  at  Buyer's expense) so that it will properly record the temperature of the
LPG  flowing  through  the  meter  or  meters.  The  arithmetical average of the
temperatures  recorded  while LPG is passing through the meter or meters in each
chart  period  shall  be  used  in computing measurements for that chart period.

     3.3  The  specific  gravity  of the LPG flowing through the meter or meters
shall  be  assumed  to  be  .600;  however,  at  Buyer's option and expense, the
specific  gravity may be determined by use of a sampling device, connected so as
to  collect  a  representative  sample  of  the

                                      -10-
<PAGE>
LPG  delivered  hereunder.  The  specific  gravity  of  the  LPG  sample will be
determined  by  calculation  from  a  fractional  analysis  obtained  with  a
chromatograph.  The  specific  gravity  will  be  calculated from the fractional
analysis  using  data  in  the  most  up-to-date  table,  "Physical Constants of
Paraffin  Hydrocarbons,"  published  by  the Natural LPG Processors Association.
The  specific  gravity  so determined will be used in calculating LPG deliveries
for  the  Month  during  which  the  sample  is  collected.

     3.4  The  reading,  calibrating  and  adjustment  of  such  equipment  and
instruments  on  which  quantities of LPG delivered hereunder are determined and
the  changing of charts shall be done by employees, agents or representatives of
Buyerr.  Upon request of Seller, Buyer shall submit to Seller records and charts
from  such  equipment, subject to return by Seller within twenty (20) days after
receipt  thereof.  The  charts and records shall be kept on file for a period of
three  (3)  years  for  the  mutual  use  of  the  parties  hereto.

     3.5  At  least  once  each  year  Buyer,  or its affiliates, shall test and
calibrate  the  meter  and  instruments  or  cause  the  same  to  be tested and
calibrated  consistent  with  prior practices. Buyer shall give Seller notice of
the time of all tests sufficiently in advance of holding same so that Seller may
conveniently  have  Seller's  representative  present;  however,  if  Seller's
representative  is  not  present,  Buyer  or  a third party acting for Buyer may
proceed  with  the  test.

     3.6 If the metering equipment in the aggregate is found to be inaccurate by
two percent (2%) or more, registrations thereof and any payments based upon such
registrations  shall  be corrected at the rate of such inaccuracy for any period
which  is  definitely  known  or  agreed  upon, then for a period extending back
one-half  (1/2)  of the time elapsed since the last test not exceeding, however,
fifteen  (15)  days.  Following  any  test,  any  metering equipment found to be
inaccurate  to  any  degree  shall be adjusted immediately to record accurately.

     3.7  If  for  any reason any meter, scale or other system of measurement is
out of service or out of repair so that the quantity of LPG received and/or sold
by Buyercannot be ascertained or computed from the reading thereof, the quantity
of  LPG  so  received and/or sold during the period the system of measurement is
out  of repair shall be estimated and agreed upon by the parties hereto upon the
basis of the best available data, using the first of the following methods which
is  feasible:

          (a)  by  using  the  registration  of any check measuring equipment of
Buyer  if  installed  and  accurately  registering;

          (b)  by  correcting  the error if the percentage or amount of error is
ascertainable  by  calibration,  test  or  mathematical  calculation;

          (c)  by  estimating the quantity of purchases during preceding periods
under  similar  conditions  when  the  meter  was  registering  accurately.

     3.8  For  the purpose of measurement and meter calibration, the atmospheric
pressure  shall  be  assumed  to be constant at fourteen and seven-tenths (14.7)
psia.

                                      -11-
<PAGE>
     3.9 The measurement hereunder shall be corrected for deviation from Boyle's
law  at  the  pressure  and  temperature under which LPG is delivered hereunder.

     3.10  It  is agreed that the value of the EXPANSION FACTOR, REYNOLDS NUMBER
FACTOR,  SUPERCOMPRESSABILITY  FACTOR  and  MANOMETER FACTOR (where Mercury type
orifice  meters  are  used)  shall  be  actual  values.

                                   ARTICLE IV.

                               BILLING AND PAYMENT
                               -------------------

          Buyer  shall render to Seller on or before the tenth day of each month
a statement of the quantity of LPG (in terms of Gallons) purchased by Buyer from
Seller  during  the  preceding Month or for which payment is due, and the amount
payable.  Buyer shall make payment to Seller for LPG received and/or sold during
the preceding Month upon Seller's receipt of the proceeds from the sales of such
LPG.  Such  payments  shall  be  made  by wire transfer of immediately available
funds  to  the  bank account of Seller specified by Seller to Buyer from time to
time pursuant to Article VII of the Contract.  Accounting shall be by Buyer, and
billings  for  payment  shall  be  accompanied  by  a  statement  showing  such
calculations  and  adjustments, if any, as were used to arrive at the amount set
out.

                                   ARTICLE V.

                                WARRANTY OF TITLE
                                -----------------

          Seller  warrants  title to all LPG delivered hereunder by Seller, that
Seller  has  the  right  to  sell  the same and that such LPG is free from liens
(other than liens in favor of RZB Finance LLC) and adverse claims of every kind.
Seller will pay all royalties, taxes and other sums due on production of the LPG
delivered  hereunder.  Seller  further warrants that the LPG delivered hereunder
is  free  and  clear of any prior contract or dedication to any third party that
limits  or restricts the right of Seller to sell LPG to Buyer hereunder, or that
gives  such  third  party  a claim to either the proceeds paid or a claim that a
like  quantity  of  LPG be tendered to such third party at a later date.  Seller
will  indemnify  and save Buyer harmless against all loss, damage and expense of
every  character  on account of adverse claims to the LPG delivered by Seller or
of royalties, taxes, payments or other charges thereon applicable before or upon
delivery  to  Buyer.  If  Seller's  title is questioned or involved in any legal
action, Buyer may withhold payment of sums due hereunder up to the amount of the
claim  until  title  is  freed  from  such  question  or  such action is finally
determined,  or  until  Seller  furnishes  either  bond with surety or an escrow
arrangement  satisfactory  to  Buyer  and  conditioned  to  save Buyer harmless.

                                   ARTICLE VI.

                                REGULATORY BODIES
                                -----------------

                                      -12-
<PAGE>
          This Contract shall be subject to all valid and applicable laws, rules
and  regulations  of  any duly constituted governmental body having jurisdiction
herein.  Buyer  does not require any governmental authority or approval to enter
into this Contract or to accept the delivery of LPG from Seller hereunder. If at
any  time  there  is a new law, rule or regulation, or changed interpretation of
any  existing  law,  rule  or  regulation  that  requires  Buyer  to  obtain any
governmental  approval  or  authorization,  Buyer  will  notify  Seller  of  the
requirement  and will furnish Seller with any application filed, the evidence to
support  the  application  and  of  the  order  or  authorization  entered.

                                  ARTICLE VII.

                                  FORCE MAJEURE
                                  -------------

          In  the  event  either  party  hereto is rendered unable, wholly or in
part,  by force majeure, to carry out its obligations under this Contract, other
than  to  make  payments  due  hereunder, then on such party's giving notice and
reasonable  full  particulars of such force majeure in writing or by telecopy to
the  other  party  as  soon as possible after the occurrence of the cause relied
upon, the obligations of the party giving notice, so far as they are affected by
such  force majeure, shall be suspended during, but only during, the continuance
of  any  inability  so  caused.  The term "force majeure," as used herein, shall
mean  acts of God, strikes, lockouts, acts of the public enemy, wars, blockades,
insurrections,  riots, epidemics, landslides, lightning, earthquakes, hurricanes
or the threat thereof, fires, storms, floods, washouts, arrest and restraints of
rulers  of  people,  civil disturbances, the freezing of wells or lines of pipe,
requisitions,  directives,  diversions, embargoes, priorities, expropriations of
government or governmental authorities, legal or de facto, whether purporting to
act  under  some  constitution,  decree, law or otherwise, failure of pipelines,
facilities  or  lines  of pipe provided such failure of pipelines, facilities or
lines  of  pipe  is  not  reasonably  within  the  control of the party claiming
suspension,  the  partial  or  entire failure of LPG wells, and the inability to
acquire, or the delays in acquiring at reasonable cost and after the exercise of
reasonable  diligence,  such servitudes, right of way grants, permits, licenses,
approvals  and  authorizations  by  regulatory  bodies, and/or such supplies and
materials (or permission from regulatory bodies to use supplies and materials on
hand),  as  may  be necessary in order that obligations assumed hereunder may be
lawfully performed in the manner herein contemplated.  Upon the occurrence of an
event  constituting  force  majeure,  the  same  shall,  so  far as possible, be
remedied with all reasonable dispatch.  The settlement of strikes or other labor
difficulties  shall  be  entirely  within the discretion of the party having the
difficulty,  and  the above requirement that any force majeure shall be remedied
with  all  reasonable  dispatch  shall  not require the settlement of strikes or
other  labor  difficulties  by  acceding  to  the  demands of any opposing party
therein  when  such  course is inadvisable in the discretion of the party having
the  difficulty.

                                  ARTICLE VIII.

                                    INDEMNITY
                                    ---------

                                      -13-
<PAGE>
          Buyer  shall  indemnify,  defend  and  hold  Seller  harmless from and
against  all  loss, cost and expense, including court costs and attorney's fees,
for  any  claims, suits, judgments, demands, actions or liability growing out of
the  operations  conducted  hereunder  by  Buyer  or arising while the LPG is in
Buyer's  exclusive  control  and  possession.  Likewise, Seller shall indemnify,
defend  and  hold  Buyer  harmless  from and against any loss, cost and expense,
including  court  costs  and  attorney's fees, for any claims, suits, judgments,
demands,  actions  or liability growing out of Seller's operations of its wells,
leases,  equipment,  pipelines and other facilities and appurtenances thereto or
arising  while  the  LPG  is  in  Seller's  exclusive  control  and  possession.

                                   ARTICLE IX.

                                  MISCELLANEOUS
                                  -------------

     9.1  Entirety  -  This  Contract  contains the entire agreement between the
parties  and  there are no oral promises, agreements or warranties affecting it.

     9.2  Titles  -  The  numbering and titling of particular provisions of this
Contract  are  for  the  purpose of facilitating administration and shall not be
construed  as  having  any  substantive  effect  on  the terms of this Contract.

     9.3  Waiver  -  Waiver of any breach or failure to enforce any of the terms
and  conditions  of this Contract at any time shall not in any way affect, limit
or  waive  either party's right thereafter to enforce and compel compliance with
every  term  and  condition  hereof.

     9.4  Time  of  Essence  -  Time  is  of the essence in this Contract in all
respects.

     9.5 Preparer - This Contract was prepared jointly by the parties hereto and
not  by  either  party  to  the  exclusion  of  the  other.

     9.6  Severability  -  In  the  event  that  any clause or provision in this
Contract shall, for any reason, be deemed illegal, invalid or unenforceable, the
remaining  provisions and clauses shall not be affected, impaired or invalidated
and  shall  remain in full force and effect. In lieu of such illegal, invalid or
unenforceable  provision,  there  shall be added automatically as a part of this
Contract  a  provision  as  similar  in  terms  to  such  illegal,  invalid  or
unenforceable  provision as may be possible and be legal, valid and enforceable.

     9.7  Governing  Law - As to all matters of construction and interpretation,
this  Contract  shall  be interpreted, construed and governed by the laws of the
State  of  Texas,  excluding  conflicts of law principles that might require the
application  of  the  laws  of  another  jurisdiction.

     9.8  Damages - Neither party shall be liable to the other for any indirect,
incidental,  consequential  or  punitive damages which may occur, in whole or in
part,  as  a  result  of  a party's performance or non-performance of any of the
terms  and  conditions  of  this  Contract.

                      End of General Terms and Conditions

                                      -14-
<PAGE>THIS  OPTION  AND  THE  LIMITED  LIABILITY  COMPANY  INTERESTS  PURCHASABLE UPON
EXERCISE  HEREOF  HAVE  NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED,  OR  UNDER  ANY STATE SECURITIES LAWS.  IT MAY NOT BE SOLD, OFFERED FOR
SALE,  PLEDGED  OR  HYPOTHECATED  IN  THE  ABSENCE  OF AN EFFECTIVE REGISTRATION
STATEMENT  AS  TO  THE  SECURITIES  UNDER  SAID  ACT  OR  AN  OPINION OF COUNSEL
SATISFACTORY  TO  THE  COMPANY  THAT  SUCH  REGISTRATION  IS  NOT  REQUIRED.

                              UNIT PURCHASE OPTION

                            Void after July 10, 2006

Option  No.  1                                                  July  10,  2003

     FOR  VALUE  RECEIVED  and pursuant to the terms of a letter agreement dated
November  29,  2002,  between  Shore  Capital LLC and Penn Octane Corporation, a
Delaware corporation ("Penn Octane"), and a resulting employment agreement dated
                       -----------
May  13, 2003, between Penn Octane and Richard Shore, Jr., the undersigned, Penn
Octane,  hereby certifies that Shore Capital LLC (the "Holder"), or  assigns, is
                                                       ------
entitled,  subject  to  the  terms set forth below, to purchase from Penn Octane
after  the date (the "Distribution Date") Penn Octane completes the distribution
(the  "Distribution") to its stockholders of all of the outstanding common units
       ------------
of Rio Vista Energy Partners L.P., a Delaware limited partnership ("Rio Vista"),
                                                                    ---------
and before 5:00 P.M. New York time, on July 10, 2006 (the "Expiration Date") 25%
of  the  outstanding  Units  (as  defined below) of Rio Vista GP LLC, a Delaware
limited  liability  company  (the  "Company") for a purchase price per Unit (the
                                    -------
"Exercise  Price")  equal  to the number of Units to be purchased divided by the
 ---------------
pro rata portion of the tax basis capital of Rio Vista immediately following the
Distribution.

     As  used herein the following terms, unless the context otherwise requires,
have  the  following  respective  meanings:

     (a)  The  term  "Company" includes any corporation that shall succeed to or
assume  the  obligations  of  the  Company.

     (b)  The term "Exercise Price" shall have the meaning ascribed to such term
in  the  first  paragraph  hereof.

     (c)  The  term "Limited Liability Company Agreement" shall mean the Amended
and  Restated Limited Liability Company Agreement of the Company dated September
8,  2004.

     (c) The term "Purchase Price" shall mean the amount equal to the product of
the  Exercise  Price  and  the  number  of  Units  to be purchased upon the full
exercise  of  this  Option.

     (d)  The  term  "Units" shall have the meaning ascribed to such term in the
Limited  Liability  Company  Agreement.

     1.  Exercise  of Option. This Option may be exercised in full by the Holder
         --------------------
hereof at any time after the Distribution Date and before the Expiration Date by
surrender  of  this  Option,

<PAGE>
with  the  form  of  subscription,  addendum  agreement to the limited liability
company  agreement  of the Company and the Voting Agreement attached hereto duly
executed  by  such  Holder,  to  the Company and Penn Octane at their respective
principal  offices,  accompanied by payment of the Purchase Price.  The Purchase
Price  shall  be  paid  by  cash  or  check  payable to the order of Penn Octane
Corporation.

     2.  When Exercise Effective. The exercise of this Option shall be deemed to
         ------------------------
have  been  effected  immediately prior to the close of business on the business
day  on  which  this  Option  is  surrendered  as  provided in Section 1 and the
documents referenced in Section 1 are duly executed and delivered as provided in
Section  1,  and at such time the Holder shall be deemed to be the record holder
of  such  Units  for  all  purposes.

     3.  Delivery on Exercise. As soon as practicable after the exercise of this
         ---------------------
Option  in full, and in any event within ten (10) business days thereafter, Penn
Octane  at  its  expense  (including  the  payment by it of any applicable issue
taxes)  will  cause  to  be  delivered  to  the  holder  hereof a certificate or
certificates  for  the number of Units to which such holder shall be entitled on
such  exercise.

     4.  Investment  Intent.  Unless  a current registration statement under the
         ------------------
Securities  Act  of  1933, as amended (the "Securities Act"), shall be in effect
with respect to the securities to be purchased upon exercise of this Option, the
Holder  hereof, by accepting this Option, covenants and agrees that, at the time
of  exercise  hereof,  and  at  the  time of any proposed transfer of securities
acquired  upon exercise hereof, such Holder will deliver to the Company and Penn
Octane  a  written  statement that the securities acquired by the Holder are for
such  Holder's  own account, and are not acquired with a view to, or for sale in
connection  with,  any  distribution  thereof  (or  any  portion thereof) except
pursuant  to  current  registration  statement  under  the  Securities Act or an
available  exemption  from  registration.

     5.  Transfer.  This  Option  is  not transferable without the prior written
         --------
consent  of  Penn  Octane.

     6.  No  Rights  or  Liability as a Member. This Option does not entitle the
         --------------------------------------
Holder  hereof  to  any voting rights or other rights as a Member (as defined in
Limited  Liability  Company Agreement).  No provisions hereof and no enumeration
herein  of  the rights or privileges of the Holder hereof shall give rise to any
liability  of such holder as a Member of the Company.  The Units to be purchased
pursuant  to  this  Option  are  subject  to  the terms of the Limited Liability
Company  Agreement.  The Holder shall not be deemed to be a Member and shall not
have  any rights of a Member or rights of an assignee from a Member with respect
to,  any  Units subject to this Option unless and until the Holder has satisfied
all  requirements  for  exercise  of  this Option pursuant to its terms.  Before
receiving  the  Units  subject to this Option, the Holder shall take such action
and  execute such documents as the Company and Penn Octane may require to become
a  Member  of  the  Company.

     7.  Damages.  Penn Octane recognizes and agrees that the Holder hereof will
         -------
not  have  an  adequate  remedy if Penn Octane fails to comply with the terms of
this  Option and that damages will not be readily ascertainable, and Penn Octane
expressly  agrees  that,  in  the  event of such failure, it shall not oppose an
application  by  the  Holder  of  this  Option  or  any  other  person

                                        2
<PAGE>
entitled  to  the  benefits of this Option requiring specific performance of any
and all provisions hereof or enjoining the Penn Octane from continuing to commit
any  such  breach  of  the  terms  hereof.

     8.  Notices.  All  notices  and  other communications required or permitted
         -------
hereunder shall be in writing and sent (a) by telecopy if the sender on the same
day  sends  a  confirming copy of such notice by a recognized overnight delivery
service  (charges  prepaid),  or (b) by first class mail, or (c) by a recognized
overnight  delivery  service  (with  charges  prepaid),  addressed (1) if to the
Holder  of this Option, at such Holder's address as it appears in the records of
Penn  Octane (unless otherwise indicated by such Holder), (2) if to Penn Octane,
at  its  office  at  77-530  Enfield  Lane,  Building D, Palm Desert, CA  92211,
Attention:  Chief  Executive  Officer,  or  at such other address as Penn Octane
shall  have  furnished  to  the Holder of the Option in writing or (3) if to the
Company, at its office at 820 Gessner Road, Suite 1285, Houston, Texas  77024 or
at  such other address as the Company or Penn Octane shall have furnished to the
Holder  of  the  Option  in  writing

     9.  Payment  of  Taxes.  Penn Octane shall pay all transfer taxes and other
         ------------------
governmental  charges (not including state and federal income taxes) that may be
imposed  in  respect  to  the  issue or delivery of the Units purchased upon the
exercise  of  this  Option. At the time this Option is exercised, in whole or in
part,  or  at  any  time  thereafter  as requested by Penn Octane, Holder hereby
authorizes withholding from payroll and any other amounts payable to Holder, and
otherwise  agrees  to  make adequate provision for, any sums required to satisfy
the federal, state, local and foreign tax withholding obligations of Penn Octane
or  an  affiliate,  if  any,  which  arise in connection with this Option.  This
Option  is not exercisable unless the tax withholding obligations of Penn Octane
and/or  any  affiliate  are  satisfied.  Accordingly,  Holder may not be able to
exercise  this  Option  when desired even though this Option is vested, and Penn
Octane shall have no obligation to issue a certificate for such Units or release
such  Units  from  any  escrow  provided  for  herein.

     10.  Governing  Law.  All issues and questions concerning the construction,
          --------------
validity,  enforcement  and  interpretation  of  this Option and the attachments
hereto  shall  be governed by, and construed in accordance with, the laws of the
State  of  Texas  without  giving effect to any choice of law or conflict of law
rules  or  provisions  (whether of the State of Texas or any other jurisdiction)
that  would cause the application of the laws of any jurisdiction other than the
State  of Texas.  In furtherance of the foregoing, the internal law of the State
of  Texas  shall control the interpretation and construction of this Option (and
all  attachments hereto), even though under that jurisdiction's choice of law or
conflict  of  law analysis, the substantive law of some other jurisdiction would
ordinarily  apply.

     11.  Consent  to  Jurisdiction.
          -------------------------

          (a)  Each of the parties hereto hereby irrevocably and unconditionally
submits, for itself and its property, to the exclusive jurisdiction of any Texas
state  court or federal court o the United States of America sitting in Houston,
Texas,  and  any  appellate  court from any thereof, in any action or proceeding
arising  out  of  or relating to this Agreement or the transactions contemplated
hereby  or  for recognition or enforcement of any judgment relating thereto, and
each  of  the  parties hereto hereby irrevocably and unconditionally agrees that
all  claims  in  respect

                                        3
<PAGE>
of any such action or proceeding may be heard and determined in such Texas state
court  or,  to  the extent permitted by law, in such federal court.  Each of the
parties  hereto  agrees  that  a final judgment in any such action or proceeding
shall  be  conclusive  and may be enforced in other jurisdictions by suit on the
judgment  or  in  any  other  manner  provided  by  law.

          (b)  Each of the parties hereto hereby irrevocably and unconditionally
waives,  to  the  fullest  extent  it  may  legally  and  effectively do so, any
objection which it may now or hereafter have to the laying of venue of any suit,
action  or  proceeding  arising  out  of  or  relating  to  this  Option  or the
transactions  contemplated  hereby  in any Texas state or federal court. Each of
the parties hereto hereby irrevocably waives, to the fullest extent permitted by
law,  the  defense of an inconvenient forum to the maintenance of such action or
proceeding  in  any  such  court.

          (c)  Each  party  to  this  Option  irrevocably consents to service of
process  in the manner provided for notices in Section 8. Nothing in this Option
will  affect the right of any party to this Option to serve process in any other
manner  permitted  by  law.

     12.  Waiver  of  Jury  Trial.

          (a)  EACH PARTY ACKNOWLEDGES AND AGREES THAT ANY CONTROVERSY WHICH MAY
ARISE  UNDER  THIS OPTION IS LIKELY TO INVOLVE COMPLICATED AND DIFFICULT ISSUES,
AND  THEREFORE IT HEREBY IRREVOCABLY AND UNCONDITIONALLY WAIVES ANY RIGHT IT MAY
HAVE  TO  A  TRIAL  BY  JURY IN RESPECT OF ANY LITIGATION DIRECTLY OR INDIRECTLY
ARISING  OUT  OF  OR  RELATING  TO  THIS OPTION OR THE TRANSACTIONS CONTEMPLATED
HEREBY  OR  THEREBY.

          (b)  EACH PARTY CERTIFIES AND ACKNOWLEDGES THAT (i) NO REPRESENTATIVE,
AGENT  OR  ATTORNEY  OF ANY OTHER PARTY HAS REPRESENTED, EXPRESSLY OR OTHERWISE,
THAT SUCH OTHER PARTY WOULD NOT, IN THE EVENT OF LITIGATION, SEEK TO ENFORCE THE
FOREGOING  WAIVER,  (ii)  IT  UNDERSTANDS AND HAS CONSIDERED THE IMPLICATIONS OF
SUCH  WAIVER,  (iii)  IT  MAKES  SUCH  WAIVER  VOLUNTARILY, AND (iv) IT HAS BEEN
INDUCED  TO ENTER INTO THIS OPTION BY, AMONG OTHER THINGS, THE MUTUAL WAIVER AND
CERTIFICATIONS  IN  THIS  SECTION  12.

     13.  Miscellaneous. This Option and any term hereof may be changed, waived,
          -------------
discharged  or  terminated  only by an instrument in writing signed by the party
against  which  enforcement  of such change, waiver, discharge or termination is
sought.  The  headings  in  this  Option are for purposes of reference only, and
shall  not  limit  or  otherwise  affect  any  of  the  terms  hereof.

                                 PENN OCTANE CORPORATION

                                 By:  Jerome B. Richter
                                      ------------------------------------------
                                      Jerome B. Richter, Chief Executive Officer

                                        4
<PAGE>
                                 ACKNOWLEDGED AND AGREED TO
                                 WITH RESPECT TO ITS RIGHTS AND
                                 OBLIGATIONS HEREUNDER:

                                 SHORE  CAPITAL LLC

                                 By: /s/ Richard Shore, Jr.
                                     -------------------------------------------
                                     Richard Shore, Jr., President

                                        5
<PAGE>
                             ATTACHMENT A TO OPTION

                              FORM OF SUBSCRIPTION

                    (TO BE SIGNED ONLY ON EXERCISE OF OPTION)

     To:  PENN  OCTANE  CORPORATION

     The undersigned, the holder of the within Option, hereby irrevocably elects
to  exercise the purchase rights represented by such Option for, and to purchase
thereunder,  25% of the outstanding Units of RIO VISTA GP LLC and herewith makes
payment  of  $___________  therefor,

     and requests that the certificates for such units be issued in the name of,
and  delivered  to  the  undersigned,  whose  address is________________________
____________________________________.

                                         _______________________________________
                                         (Signature must conform in all
                                         respects to name of holder as specified
                                         on the face of the Option)

                                         _______________________________________

                                         _______________________________________
                                         Address

Dated: ________________________

                                        6
<PAGE>
                             ATTACHMENT B TO OPTION

              ADDENDUM AGREEMENT TO THE LIMITED LIABILITY COMPANY
                          AGREEMENT OF RIO VISTA GP LLC

                                        7
<PAGE>
                             ATTACHMENT C TO OPTION

                                VOTING AGREEMENT

                                        8
<PAGE>

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00074-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00074-of-00352.parquet"}]]