How long do you intend to keep it? Oil change interval affects engine life at the end, not beginning. If you get rid of it at 100k, it might be fine with 1 or 2 changes on syntetic. You would never see the effects. If you want to drve it untill the engine is dead, change that [bleep] often. And remembet, if you want to protect your engine, you need to be dropping good oil out of it, not used up crap.
