Originally posted by contourfreak22:
i heard if you add synthetic from regular oil it can ruin the oil seals.

contourfreak, that's an old wives tale. WAY back in the day (early-mid '70s) there were in fact seal-compatibility issues with some of the very earliest synthetic oils. Those issues were resolved 25 years ago. You can switch to synthetic at any time.

If your motor is heavily sludged-up and/or has not been properly maintained, switching to synth oil CAN cause small leaks as it cleans out the old hardened crap that may have been plugging up dried-out seals, but those leaks will clear up quickly.

'99 'Tour (actually my brother-in-law's, but I'm the family wrench)