Originally Posted By: JOD
There is no reason that a group III synthetic is going to be more likely to leak than a group II base oil, and any suggestion that's the case is just based on ignorance. The base oils are very similar, the GIII is just more refined-how on earth is that going to cause a leak?
It could be a reaction with one of the additives, or it just could be coincidence....or it could be some spilled oil remaining from the filter swap, which is a bit of a pain on that car. I'd try to figure out the source of the leak before trying any of the various fixes suggested.
Here's more real world experiences (or ignorance and coincidences as you call it). 02 Camry I4 199k. Oil disappears much more rapidly using 0w20. Using a quart every 3k now, before w/5w30 it was 1/2 qt every 5k. Valve cover and oil pan both started leaking, never did before. My options are replace valve seals, engine teardown for rings, replace all gaskets to run 0w20, or retreat to thick goopy 5w30 and continue on. Maybe I'm ignorant, but I'd rather go for that thick goopy M1 5w30.