when a car sees a lot of varnish on the inside and on the dip stick what does that mean? or what can it mean? my gf has 85k miles on her 05 corolla and it has seen ALOT of city driving. as with most girls she just gets in and slams the gas lol.. i have been changing her oil for over a year (the length of time i have been seeing her).. she supposedly changed the oil at 5k miles before i met her. any ideas??. all of her oil changes have been at jiffy lube type places.. i cleaned the dipstick off a few changes ago and no varnish back on it yet but it was bad.