<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        SEPTEMBER 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)

                CALIFORNIA                           33-0064245
      (State or other jurisdiction of             (I.R.S. Employer
      incorporation or organization)            Identification Number)

 23041 AVENIDA DE LA CARLOTA, SUITE 400, LAGUNA HILLS, CA     92653
      (Address of principal executive offices)              (Zip Code)

                                 (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 [ ]



                                      -1-
<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 September 30, 1998 (Unaudited) and
     December 31, 1997                                            3

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

Statements of Cash Flows for the nine months ended
     September 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            8


PART II. OTHER INFORMATION

Item 6.  Exhibits and Reports on Form 8-K                        10


SIGNATURES                                                       11
</TABLE>




                                      -2-
<PAGE>   3

                        DEL TACO RESTAURANT PROPERTIES II

                                 BALANCE SHEETS



<TABLE>
<CAPTION>
                                                    SEPTEMBER 30          December 31
                                                       1998                   1997
                                                    -----------           -----------
                                                    (UNAUDITED)
<S>                                                 <C>                   <C>        
                                     ASSETS
CURRENT ASSETS:
  Cash                                              $   143,641           $   119,687
  Receivable from General Partner (Note 4)               39,583                38,332
  Deposits                                                1,937                 1,000
                                                    -----------           -----------
    Total current assets                                185,161               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                      1,530,906             1,490,271
                                                    -----------           -----------
                                                      2,412,929             2,453,564
                                                    -----------           -----------

                                                    $ 2,598,090           $ 2,612,583
                                                    ===========           ===========


                        LIABILITIES AND PARTNERS' EQUITY

CURRENT LIABILITIES:
  Payable to Limited Partners                       $    11,858           $     6,608
  Accounts Payable                                        2,921                 7,365
                                                    -----------           -----------
    Total current liabilities                            14,779                13,973
                                                    -----------           -----------

PARTNERS' EQUITY:
  Limited Partners                                    2,606,528             2,621,674
  General Partner-Del Taco, Inc.                        (23,217)              (23,064)
                                                    -----------           -----------
                                                      2,583,311             2,598,610
                                                    -----------           -----------

                                                    $ 2,598,090           $ 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              NINE MONTHS ENDED
                                           SEPTEMBER 30                   SEPTEMBER 30
                                      1998            1997            1998            1997 
                                    --------        --------        --------        --------
<S>                                 <C>             <C>             <C>             <C>     
REVENUES:
  Rent (Notes 3 and 4)              $127,142        $117,027        $357,330        $333,692
  Interest                               870             673           1,658           2,245
  Other                                1,225           1,900           2,175           2,150
                                    --------        --------        --------        --------
                                     129,237         119,600         361,163         338,087
                                    --------        --------        --------        --------

EXPENSES:
  General and administrative           8,602           7,393          42,093          38,810
  Depreciation                        13,545          13,545          40,635          85,583
                                    --------        --------        --------        --------
                                      22,147          20,938          82,728         124,393
                                    --------        --------        --------        --------

Net income                          $107,090        $ 98,662        $278,435        $213,694
                                    ========        ========        ========        ========

Net income per Limited
  Partnership Unit (Note 2)         $   3.93        $   3.62        $  10.21        $   7.83
                                    ========        ========        ========        ========
</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>
                                                            NINE MONTHS ENDED
                                                              SEPTEMBER 30
                                                         1998              1997 
                                                       ---------         ---------
<S>                                                    <C>               <C>      
CASH FLOWS FROM OPERATING ACTIVITIES:

 Net income                                            $ 278,435         $ 213,694
 Adjustments to reconcile net income to net
  cash provided by operating activities:
    Depreciation                                          40,635            85,583
    Increase in payable to Limited Partners                5,250               408
    (Increase) decrease in receivable from
      General Partner                                     (1,251)              316
    (Decrease) increase in accounts payable               (4,444)              184
    Increase in deposits                                    (937)               --
                                                       ---------         ---------

      Net cash provided by operating activities          317,688           300,185

CASH FLOWS FROM FINANCING ACTIVITIES:

 Cash distributions to partners                         (293,734)         (293,160)
                                                       ---------         ---------

Net increase in cash                                      23,954             7,025

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

Ending cash balance                                    $ 143,641         $ 124,382
                                                       =========         =========
</TABLE>




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



                                      -5-
<PAGE>   6

                        DEL TACO RESTAURANT PROPERTIES II

                          NOTES TO FINANCIAL STATEMENTS

                               SEPTEMBER 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 September 30, 1998,
the results of operations and cash flows for the nine month periods ended
September 30, 1998 and 1997 have been included. Operating results for the three
and nine months ended September 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.

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 September 30, 1998 and 1997.



                                      -6-
<PAGE>   7

DEL TACO RESTAURANT PROPERTIES II
NOTES TO FINANCIAL STATEMENTS - CONTINUED
SEPTEMBER 30, 1998


NOTE 3 - LEASING ACTIVITIES - (Continued)

For the three months ended September 30, 1998, the five restaurants operated by
Del Taco, for which the Registrant is the lessor, had combined, unaudited sales
of $1,059,512 and net income of $80,355 as compared to $975,227 and $56,754
respectively, for the corresponding period in 1997. Net income by restaurant
includes charges for general & administrative expenses incurred in connection
with supervision of restaurant operations and interest expense.

For the nine months ended September 30, 1998, the five restaurants operated by
Del Taco, for which the Registrant is the lessor, had combined, unaudited sales
of $2,977,753 and net income of $186,142 as compared to $2,780,771 and $137,227
respectively, for the corresponding period in 1997.

For the three months and nine months ended September 30, 1998, the Clay Street
restaurant in Pedley (Riverside), California reported net income of $2,592 and
$6,602 as compared to net income of $155 and a net loss of $1,127 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 September. The September rent was collected on October 13, 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.

NOTE 5 - DISTRIBUTIONS

On October 12, 1998, a distribution to the Limited Partners of $123,565 or
approximately $4.58 per Limited Partnership Unit, was approved. Such
distribution was paid on October 15, 1998. The General Partner also received a
distribution of $1,248 with respect to its 1% partnership interest.



                                      -7-
<PAGE>   8

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 September 30, increased from $117,027
in 1997 to $127,142 in 1998. The Registrant had rental revenues of $333,692 for
the nine months ended September 30, 1997, and the rental revenue increased to
$357,330 in 1998. The increase in revenues is directly attributable to increased
sales at the restaurants.



                                      -8-
<PAGE>   9

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

<TABLE>
<CAPTION>
                                           THREE MONTHS ENDED              NINE MONTHS ENDED
                                              SEPTEMBER 30                   SEPTEMBER 30
                                          1998            1997            1998            1997
                                        --------        --------        --------        --------
<S>                                     <C>             <C>             <C>             <C>     
Bear Valley Rd., Victorville, CA        $ 25,471        $ 22,836        $ 70,744        $ 65,684

West Valley Blvd., Colton, CA             28,092          26,604          76,241          70,707

Palmdale Blvd., Palmdale, CA              21,980          21,270          61,210          67,478

DeAnza Country Shopping Center,           17,047          14,315          47,855          40,487
  Pedley, CA

Varner Road, Thousand Palms, CA           34,552          32,002         101,280          89,336
                                        --------        --------        --------        --------

          Total                         $127,142        $117,027        $357,330        $333,692
                                        ========        ========        ========        ========
</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
                                                  --------------------------------

                                                        Nine Months Ended
                                                           September 30
                                                     1998                 1997
                                                   -------              -------
<S>                                                <C>                  <C>   
Accounting fees                                      57.46%               57.23%
Distribution of
  information to
  Limited Partners                                   40.48                40.87
Other                                                 2.06                 1.90
                                                   -------              -------
                                                    100.00%              100.00%
                                                   =======              =======
</TABLE>

Certain reclassifications have been made to the fiscal year 1997 general and
administrative expenses to conform to the fiscal year 1998 presentation.
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 September 30 from $7,393 in 1997 to $8,602 in 1998. For the nine
months ended September 30, general and administrative expenses increased from
$38,810 in 1997 to $42,093 in 1998. General and administrative expenses
increased due to increased costs of printing and distribution. Depreciation
expense was $13,545 for the three months ended September 30, 1998 and 1997,
respectively. The Registrant incurred depreciation expense in the amount of
$40,635 for the nine months ended September 30, 1998 and $85,583 for the nine
months ended September 30, 1997. The decrease in depreciation expense is a
result of certain equipment becoming fully depreciated.



                                      -9-
<PAGE>   10

For the three months ended September 30, 1998 revenues increased $9,637 and
expenses increased $1,209, creating an increase in net income from $98,662 in
1997 to $107,090 in 1998. As a result of increased revenues totaling $23,076 for
the nine months ended September 30, 1998 and decreased expenses totaling $41,665
for the nine months ended September 30, 1998, the net income of the Registrant
increased from $213,694 for the nine months ended September 30, 1997 to $278,435
for the corresponding period in 1998.

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.

Management does not believe the operations of the Company will be significantly
impacted by the year 2000 software issue and does not believe the year 2000
software issue will materially effect the Company's operations, financial
position or cash flows.


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 nine months ended 
     September 30, 1998.



                                      -10-
<PAGE>   11

                                   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:  October 30, 1998                      /s/ Robert J. Terrano      
                                             -----------------------------------
                                             Robert J. Terrano
                                             Executive Vice President,
                                             Chief Financial Officer


Date:  October 30, 1998                      /s/ C. Douglas Mitchell       
                                             -----------------------------------
                                             C. Douglas Mitchell
                                             Vice President and Corporate
                                             Controller



                                      -11-
<PAGE>   12

                                 EXHIBIT INDEX


Exhibit
Number                             Description
------                             -----------

  27                          Financial Data Schedule.