My 1998 T5 (auto) has just passed 70K ( had a timing belt/ serpentine belt replacement), and I was thinking about switching over to synthetic motor oil. However, at 70K miles, will I notice an appreciable difference in fuel economy, and will the engine "thank me" in the long run by way of reducing it's internal work load?

Honestly, in having the car about 2 years, the car has run very well, averaging 22mph in the city with lots of stop/start driving and in LA heat, frequently running the A/C. I also run V rated tires.

But, some techs have told "if it ain't broke,.....", meaning stick with a good mineral/ dino oil and change it regularly is just as good for the car, and far less $$.

Opinions? And, if I DO change to synthetic, does it matter which brand? Must I flush the engine with something before switching over, etc...?


I know this is a "grey area", and I'll probably get opinions on BOTH sides, but would like to get some more hard evidence, now that it's paid for and I want it to last another 70K if possible!

TIA,
Harley