[Landshark]

Originally Posted by eviljay

Synthetic is a beautiful thing to use... on a fresh rebuild. One thing I learned from my rotary days, old motors dont like it. If from day one it had synth it will be fine for the life of the engine, but on an engine that has had natural oil all its life is the quickest way to need a future rebuild, other than running with no oil at all.

yep. as i understand it, synthetic will clean all the goop around the seals that keeps them from leaking on older engines, and then they will leak.

i think i read somewhere that if you have ~40k or more on your engine, don't switch to synthetic. all internet conjecture, but i've seen plenty of older engines leak with a switch to synthetic.

if its specified from the factory to run synth (new Porsches, etc.) use it - if not, save yourself some money (and potential leaks).