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                                                             EXHIBIT (a)(1)(iii)

                              MOTORVAC LETTERHEAD

                                 August 3, 2000

Dear Stockholder:

     MotorVac Technologies, Inc. is offering to purchase up to 1,612,166 shares
of our common stock (representing approximately 35% of the currently outstanding
shares), at a price of $3.50 per share subject to the terms and conditions of
the Offer to Purchase.

     We will purchase all of the shares that are properly tendered (and are not
withdrawn) for cash at the purchase price of $3.50, net to the selling
stockholder.

     If you do not wish to participate in the offer, you do not need to take any
action.

     The offer is explained in detail in the enclosed Offer to Purchase and
Letter of Transmittal. If you want to tender your shares, the instructions on
how to do so are also explained in detail in the enclosed materials. I encourage
you to read these materials carefully before making any decision with respect to
the offer.

     Neither MotorVac nor our Board of Directors or senior management makes any
recommendation to any stockholder whether to tender all or any shares. Our
continuing directors and executive officers have advised us that they do not
intend to tender any shares in this offer.

                                      Sincerely,

                                      /s/ Lee W. Melody
                                      President and Chief
                                      Executive Officer