<PAGE>   1
 
================================================================================
 
                                 UNITED STATES
 
                       SECURITIES AND EXCHANGE COMMISSION
 
                             WASHINGTON, D.C. 20549
 
                                   FORM 10-Q
(MARK ONE)
 
[X]  QUARTERLY REPORT UNDER SECTION 13 OR 15(d) OF THE SECURITIES
     EXCHANGE ACT OF 1934
 
FOR THE QUARTERLY PERIOD ENDED,                   JUNE 30, 1998
                               -------------------------------------------------

                                       OR
 
[ ]  TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
     EXCHANGE ACT OF 1934
 
FOR THE TRANSITION PERIOD FROM                      TO
                              ----------------------  ------------------------
COMMISSION FILE NO. 2-92121
 
                       DEL TACO RESTAURANT PROPERTIES II
                        A CALIFORNIA LIMITED PARTNERSHIP
             (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)
 
<TABLE>
<S>                                                          <C>
 
                         CALIFORNIA                                    33-0064245
              (STATE OR OTHER JURISDICTION OF                       (I.R.S. EMPLOYER
               INCORPORATION OR ORGANIZATION)                      IDENTIFICATION NO.)
 
   23041 AVENIDA DE LA CARLOTA, LAGUNA HILLS, CALIFORNIA                  92653
          (ADDRESS OF PRINCIPAL EXECUTIVE OFFICES)                     (ZIP CODE)
</TABLE>
 
                                 (949) 462-9300
              (REGISTRANT'S TELEPHONE NUMBER, INCLUDING AREA CODE)
 
     INDICATE BY CHECK MARK WHETHER THE REGISTRANT (1) HAS FILED ALL REPORTS
REQUIRED TO BE FILED BY SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF
1934 DURING THE PRECEDING 12 MONTHS (OR FOR SUCH SHORTER PERIOD THAT THE
REGISTRANT WAS REQUIRED TO FILE SUCH REPORTS), AND (2) HAS BEEN SUBJECT TO SUCH
FILING REQUIREMENTS FOR THE PAST 90 DAYS.  YES  [X]   NO [ ]

================================================================================
<PAGE>   2

                                      INDEX

                        DEL TACO RESTAURANT PROPERTIES II
                        ---------------------------------


<TABLE>
<CAPTION>
PART I.  FINANCIAL INFORMATION                                          PAGE NUMBER
------------------------------                                          -----------

<S>                                                                     <C>    
Item 1.  Financial Statements and Supplementary Data

Balance Sheets at June 30, 1998 (Unaudited) and
     December 31, 1997                                                        3

Statements of Income for the three and six months ended
     June 30, 1998 and 1997 (Unaudited)                                       4

Statements of Cash Flows for the six months ended
     June 30, 1998 and 1997 (Unaudited)                                       5

Notes to Financial Statements                                                 6


Item 2.  Management's Discussion and Analysis of
         Financial Condition and Results of Operations                        9


PART II. OTHER INFORMATION
--------------------------

Item 6.  Exhibits and Reports on Form 8-K                                    11


SIGNATURES                                                                   12
----------
</TABLE>


                                      -2-
<PAGE>   3

                        DEL TACO RESTAURANT PROPERTIES II
                        ---------------------------------

                                 BALANCE SHEETS
                                 --------------


<TABLE>
<CAPTION>
                                                              June 30,   December 31,
                                                                1998         1997
                                                             ----------   ----------
                                                             (UNAUDITED)
<S>                                                          <C>          <C>       
                                     ASSETS
                                     ------

CURRENT ASSETS:
  Cash                                                       $  125,114   $  119,687
  Receivable from General Partner (Note 4)                       41,002       38,332
  Deposits                                                        2,406        1,000
                                                             ----------   ----------
    Total current assets                                        168,522      159,019
                                                             ----------   ----------

PROPERTY AND EQUIPMENT, AT COST:
  Land and improvements                                       1,806,006    1,806,006
  Buildings and improvements                                  1,238,879    1,238,879
  Machinery and equipment                                       898,950      898,950
                                                             ----------   ----------
                                                              3,943,835    3,943,835
  Less--accumulated depreciation                              1,517,361    1,490,271
                                                             ----------   ----------
                                                              2,426,474    2,453,564
                                                             ----------   ----------
                                                             $2,594,996   $2,612,583
                                                             ==========   ==========

                        LIABILITIES AND PARTNERS' EQUITY
                        --------------------------------

CURRENT LIABILITIES:
  Payable to Limited Partners                                $   13,273   $    6,608
  Accounts Payable                                                1,896        7,365
                                                             ----------   ----------
    Total current liabilities                                    15,169       13,973
                                                             ----------   ----------

PARTNERS' EQUITY:
  Limited Partners                                            2,603,079    2,621,674
  General Partner-Del Taco, Inc.                                (23,252)     (23,064)
                                                              ----------   ----------
                                                              2,579,827    2,598,610
                                                             ----------   ----------
                                                             $2,594,996   $2,612,583
                                                             ==========   ==========
</TABLE>


                          The accompanying notes are an
                   integral part of these financial statements


                                      -3-
<PAGE>   4

                        DEL TACO RESTAURANT PROPERTIES II
                        ---------------------------------

                              STATEMENTS OF INCOME
                              --------------------

                                   (UNAUDITED)
                                   -----------


<TABLE>
<CAPTION>
                                   THREE MONTHS ENDED            SIX MONTHS ENDED
                                         JUNE 30                      JUNE 30
                                 -----------------------      ----------------------
                                   1998           1997          1998          1997
                                 --------       --------      --------      --------
<S>                              <C>            <C>           <C>           <C>     
REVENUES:
  Rent (Notes 3 and 4)           $121,761       $112,498      $230,189      $216,665
  Interest                            317            642           787         1,572
  Other                               425            175           950           250
                                 --------       --------      --------      --------
                                  122,503        113,315       231,926       218,487
                                 --------       --------      --------      --------

EXPENSES:
  General and administrative       11,612          9,523        33,490        31,417
  Depreciation                     13,545         36,019        27,090        72,038
                                 --------       --------      --------      --------
                                   25,157         45,542        60,580       103,455
                                 --------       --------      --------      --------

Net income                       $ 97,346       $ 67,773      $171,346      $115,032
                                 ========       ========      ========      ========

Net income per Limited
  Partnership Unit (Note 2)        $3.57          $2.48         $6.28         $4.22
                                   =====          =====         =====         =====
</TABLE>


                          The accompanying notes are an
                  integral part of these financial statements.


                                      -4-
<PAGE>   5

                        DEL TACO RESTAURANT PROPERTIES II
                        ---------------------------------

                            STATEMENTS OF CASH FLOWS
                            ------------------------

                                   (UNAUDITED)
                                   -----------

<TABLE>
<CAPTION>
                                                                SIX MONTHS ENDED
                                                                     JUNE 30
                                                             -----------------------
                                                               1998           1997
                                                             --------       --------
<S>                                                          <C>            <C>     
CASH FLOWS FROM OPERATING ACTIVITIES:

 Net income                                                  $171,346       $115,032
 Adjustments to reconcile net income to net
  cash provided by operating activities:
    Depreciation                                               27,090         72,038
    Increase (decrease) in payable to
      Limited Partner                                           6,665           (109)
    Increase in receivable
      from General Partner                                     (2,670)          (741)
    Decrease in accounts payable                               (5,468)          (479)
    Increase in deposits                                       (1,406)             -
                                                             --------       --------

     Net cash provided by operating activities                195,557        185,741

CASH FLOWS FROM FINANCING ACTIVITIES:

    Cash distributions to partners                           (190,130)      (196,669)
                                                             --------       --------

Net increase (decrease) in cash                                 5,427        (10,928)

Beginning cash balance                                        119,687        117,357
                                                             --------       --------

Ending cash balance                                          $125,114       $106,429
                                                             ========       ========
</TABLE>


                          The accompanying notes are an
                  integral part of these financial statements.


                                      -5-
<PAGE>   6

                        DEL TACO RESTAURANT PROPERTIES II
                        ---------------------------------

                          NOTES TO FINANCIAL STATEMENTS
                          -----------------------------

                                  JUNE 30, 1998
                                  -------------


NOTE 1 - BASIS OF PRESENTATION

The accompanying financial statements, some of which are unaudited, have been
prepared in accordance with generally accepted accounting principles for interim
financial information and with the instructions to Form 10-Q and Article 10 of
Regulation S-X. Accordingly, they do not include all of the information and
footnotes required by generally accepted accounting principles for complete
financial statements and should therefore be read in conjunction with the
financial statements and notes thereto contained in the Registrant's annual
report on Form 10-K for the year ended December 31, 1997. In the opinion of
management, all adjustments (consisting of normal recurring accruals) necessary
to present fairly the partnership's financial position at June 30, 1998, the
results of operations and cash flows for the six month periods ended June 30,
1998 and 1997 have been included. Operating results for the three and six months
ended June 30, 1998 are not necessarily indicative of the results that may be
expected for the year ending December 31, 1998.

NOTE 2 - NET INCOME PER LIMITED PARTNERSHIP UNIT

Net income per Limited Partnership Unit is based upon the weighted average
number of Units outstanding during the periods presented which amounted to
27,006 in 1998 and 1997.

Pursuant to the Partnership Agreement, annual partnership income or loss is
allocated one percent to the General Partner and 99 percent to the Limited
Partners. Partnership gains from any sale or refinancing will be allocated one
percent to the General Partner and 99 percent to the Limited Partners until
allocated gains and profits equal losses, distributions and syndication costs
previously allocated. Additional gains will be allocated 15 percent to the
General Partner and 85 percent to the Limited Partners.


                                      -6-
<PAGE>   7

                        DEL TACO RESTAURANT PROPERTIES II
                        ---------------------------------

                    NOTES TO FINANCIAL STATEMENTS - CONTINUED
                    -----------------------------------------

                                  JUNE 30, 1998
                                  -------------


NOTE 3 - LEASING ACTIVITIES

The Registrant leases (the "Leases") certain properties (the "Properties") for
operation of restaurants to Del Taco, Inc. ("General Partner") on a triple net
basis. The Leases are for terms of 35 years commencing with the completion of
the restaurant facility located on each Property and require monthly rentals
equal to 12 percent of the gross sales of the restaurants. There is no minimum
rental under any of the Leases. The Registrant had a total of five Properties
leased as of June 30, 1998 and 1997.

For the three months ended June 30, 1998, the five restaurants operated by Del
Taco, for which the Registrant is the lessor, had combined, unaudited sales of
$1,014,674 and net income of $65,788 as compared to $937,483 and $38,972
respectively, for the corresponding period in 1997. Net income by restaurant
includes charges for general and administrative expenses incurred in connection
with supervision of restaurant operations and interest expense.

For the six months ended June 30, 1998, the five restaurants operated by Del
Taco, for which the Registrant is the lessor, had combined, unaudited sales of
$1,918,242 and net income of $105,787 as compared to $1,805,542 and $80,473
respectively, for the corresponding period in 1997.

For the three months and six months ended June 30, 1998, the Clay Street
restaurant in Pedley (Riverside), California reported net income of $3,191 and
$4,010 as compared to net income of $743 and a net loss of $1,282 respectively,
for the corresponding period in 1997.


NOTE 4 - TRANSACTIONS WITH DEL TACO

The receivable from General Partner consists primarily of rent accrued for the
month of June. The June rent was collected on July 10, 1998.

Del Taco, Inc. serves in the capacity of general partner in other partnerships
which are engaged in the business of operating restaurants and four partnerships
which were formed for the purpose of acquiring real property in California for
construction of Mexican-American restaurants for lease under long-term
agreements to Del Taco, Inc. for operation under the Del Taco trade name.

In addition, see Note 5 with respect to certain distributions to the General
Partner.


                                      -7-
<PAGE>   8

                        DEL TACO RESTAURANT PROPERTIES II
                        ---------------------------------

                    NOTES TO FINANCIAL STATEMENTS - CONTINUED
                    -----------------------------------------

                                  JUNE 30, 1998
                                  -------------


NOTE 5 - DISTRIBUTIONS

On July 15, 1998, a distribution to the Limited Partners of $102,570 or
approximately $3.80 per Limited Partnership Unit, was approved. Such
distribution was paid on August 5, 1998. The General Partner also received a
distribution of $1,036 with respect to its 1% partnership interest.


                                      -8-
<PAGE>   9

ITEM 2. MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS
-------------------------------------------------------------------------------
        OF OPERATIONS
        -------------

Liquidity and Capital Resources
-------------------------------

The Registrant commenced offering of Limited Partnership Units on September 11,
1984. By December 31, 1985, the sale of such Units provided a total
capitalization for the Registrant of $6,751,500. Fifteen percent of the cash
received from the sale of Limited Partnership Units was used to pay commissions
to brokers and to reimburse the General Partner for offering costs incurred. The
remaining funds were expended for the acquisition of sites and construction of
seven restaurants. In June 1986, the first two restaurants opened for business.
Four additional restaurants opened in 1987, and the seventh restaurant opened in
April of 1988. Approximately $5,600,000 was expended for such purposes. Two
restaurants were sold in 1994.

Since the restaurants owned by the Registrant commenced operation, cash flow
from Lease payments received from Del Taco, the Registrant's General Partner,
which leases all five remaining restaurants, has provided adequate liquidity for
operation of the Registrant. However, the Registrant's overwhelmingly
predominant source of income to meet its expenses and fund distributions to its
Limited Partners is payments from Del Taco under the Leases, comprising
primarily rent calculated on the basis of the gross sales of the restaurants
operated on the Properties, as to which there are no contractually specified
minimum or guaranteed amounts. Thus, the adequacy of the Registrant's liquidity
and capital resources in the future will depend primarily upon the gross
revenues of such restaurants as well as upon Del Taco's financial condition and
results of operations generally.

Results of Operations
---------------------

The Registrant owned seven Properties that were under long-term lease to Del
Taco for restaurant operations. Two restaurants were sold in 1994 and five are
currently operating. For the five operating Del Taco restaurants, the Registrant
receives rental revenues equal to 12 percent of restaurant sales.

Rental revenues for the three months ended June 30, increased from $112,498 in
1997 to $121,761 in 1998. The Registrant had rental revenues of $230,189 for the
six months ended June 30, 1998, representing an increase from the rental
revenues of $216,665 in 1997. The increase in revenues is directly attributable
to increased sales at the restaurants.


                                      -9-
<PAGE>   10

The following table sets forth rental revenue earned by restaurant for the
quarter and year to date:

<TABLE>
<CAPTION>
                                                       THREE MONTHS ENDED        SIX MONTHS ENDED
                                                             JUNE 30                 JUNE 30
                                                       -------------------     ---------------------
                                                        1998        1997        1998          1997
                                                       -------     -------     -------       -------
<S>                                                   <C>           <C>         <C>           <C>   
Bear Valley Rd., Victorville, CA                      $ 23,772      22,556      45,273        42,848

West Valley Blvd., Colton, CA                           25,506      23,370      48,150        44,103

Palmdale Blvd., Palmdale, CA                            20,262      22,085      39,229        46,207

DeAnza Country Shopping Center, Pedley, CA              16,145      14,041      30,808        26,173

Varner Road, Thousand Palms, CA                         36,076      30,446      66,729        57,334
                                                       -------     -------     -------       -------

                                    Total   $          121,761     112,498     230,189       216,665
                                                       =======     =======     =======       =======
</TABLE>

The following table sets forth the percentage relationship to total general and
administrative expenses of items included in the Registrant's Statements of
Income:

<TABLE>
<CAPTION>
                                           Percentage of Total
                                      General & Administrative Expense
                                      --------------------------------
                                            Six Months Ended
                                                 June 30
                                            -----------------
                                             1998       1997
                                            ------     ------
<S>                                         <C>        <C>    
Accounting fees                              64.66%     68.57%
Distribution of information to
  Limited Partners                           35.34      31.43
                                            ------     ------

                                            100.00%    100.00%
                                            ======     ====== 
</TABLE>

Operating expenses include general and administrative expenses which consist
primarily of accounting fees and costs of distribution of information to the
Limited Partners. General and administrative expenses increased for the three
months ended June 30 from $9,523 in 1997 to $11,612 in 1998. For the six months
ended June 30, general and administrative expenses increased from $31,417 in
1997 to $33,490 in 1998. General and administrative expenses increased due to
increased costs of printing and distribution. Depreciation expense was $36,019
for the three months ended June 30, 1997 and $13,545 for the three months ended
June 30, 1998. The Registrant incurred depreciation expense in the amount of
$72,038 for the six months ended June 30, 1997 and $27,090 for the six months
ended June 30, 1998. The decrease in depreciation expense was a result of
certain equipment becoming fully depreciated.

For the three months ended June 30, 1998 revenues increased $9,188 and expenses
decreased $20,385 creating an increase in net income from $67,773 in 1997 to
$97,346 in 1998. As a result of increased revenues totaling $13,439 for the six
months ended June 30, 1998 and decreased expenses totaling $42,875 for the six
months ended June 30, 1998, the net income of the Registrant increased from
$115,032 for the six months ended June 30, 1997 to $171,346 for the
corresponding period in 1998.


                                      -10-
<PAGE>   11

For the reasons stated under "Liquidity and Capital Resources" above, the
Registrant's results of operations in the future will depend primarily upon the
gross revenues of the restaurants located on the Properties leased to Del Taco
as well as upon Del Taco's financial condition and results of operations
generally.



PART II. OTHER INFORMATION
--------------------------

Item 6. Exhibits and Reports on Form 8-K

(a) Exhibit 27 - Financial Data Schedule.

(b) No reports on Form 8-K were filed during the six months ended June 30, 1998.


                                      -11-
<PAGE>   12

                                   SIGNATURES


Pursuant to the requirements of the Securities Exchange Act of 1934, the
Registrant has duly caused this report to be signed on its behalf by the
undersigned thereunto duly authorized.

                                            DEL TACO RESTAURANT PROPERTIES II
                                            (a California limited partnership)
                                            Registrant

                                            Del Taco, Inc.
                                            General Partner



Date:  July 31, 1998                        /s/ Robert J. Terrano
                                            ---------------------------
                                            Robert J. Terrano
                                            Executive Vice President,
                                            Chief Financial Officer


Date:  July 31, 1998                        /s/ C. Douglas Mitchell
                                            -----------------------
                                            C. Douglas Mitchell
                                            Vice President and Corporate
                                            Controller



                                      -12-
<PAGE>   13

                                 EXHIBIT INDEX

<TABLE>
<CAPTION>
Exhibit
Number         Description
------         -----------
<C>            <S>
  27           Financial Data Schedule.
</TABLE>