AOL Autos Repair Blog

Dear Tom,
Could you please explain the difference between synthetic oil and regular oil for a car? Is it safe to use synthetic oil? I drive a 2006 Mazda 6. Thank you.
-Monticello, VA

Answer:
Synthetic oil (though not impervious to) is highly resistant to viscosity breakdown from chemical contamination, heat, and friction inside the internal combustion engine. Viscosity breakdown is the loss of ability of the oil to lubricate an engine. This toughness is due to the chemical fortification of the base stock oil at formulation. Non-synthetic oil tends to break down more easily because it lacks this chemical fortification.

Q: I have a 1996 Toyota Camry with 133,000 miles on it. The local Toyota dealer says that it's way overdue for a transmission flush. But when I go to local quick lube shops they all refuse to do it because of the mileage on the vehicle. The transmission operates perfectly now, but the transmission fluid is not red, its a pretty dark brown. Is it wise to have a dealer do the work and risk having trouble after the job or just keep going and hope for the best?

A: The answer to this question is a tough one to arrive at. On high mileage transmissions, fluid change is a crap shoot because one has no way of knowing the extent of internal wear. When the old fluid gets burnt and worn out, the transmission experiences excessive internal wear, this causes the unit to heat up, heat causes the glue on the clutches to become brittle and to crystallize. When new fluid is introduced into the unit the high detergent aspect of the new fluid scrubs the old glue away from the back of the clutches rendering the transmission useless. Take it to the dealer, have them drop the pan to try to get a handle on the extent of internal wear then proceed from there.