What kind of oil?

I also favor synthetic, even more so because of the greatly increased
detergency. That raises a warning though - seals sometimes leak in older
cars when they are changed to synthetic. The prevailing theory is that it
dissolves deposits that the seals have been depending on, and the hardened
seals won't make the adjustment. If you can handle the possibility of
leaking main or cam seals, synthetic is clearly the way to go. (I recently
switched my daughter's '93 Accord to synthetic blend at 200K miles... it was
a success.)

Mike

 

I've heard this rumor. I inherited an '85 Buick LeSabre with
60,000, changed it over to full synthetic four years ago with no leaks and
much better winter starting. My guesss would be that if you have an older
auto with leaks, changing to synthetic might not be the smartest of
strategies. Cure the leak first.

 

I'm thinking that the factors determining whether an older car will have
problems with the leaks may include high temperatures (I had leaks after
using engine flushes - slow learner, eh? - in Phoenix) and probably a spotty
history of oil changes (most of the cars that did that were beaters.) I like
the idea of taking existing leaks as a warning sign.

Mike