My 99 Camry 2.2l is now out of warranty so I'm free to change the oil at whatever interval seems sensible. I'm in Canada, so I'm supposed to follow the severe service interval of 5000 km/3000 mi. Toyota goes out of their way (on their website) to say that one should follow the dino oil schedule even if synthetic oil is used.
My friend's Volvo has a recommended (synthetic) oil change interval of
12 000 km / 7500 mi . There is also some evidence on the web (
29 000 km!) However, the oil filter from that study is a lot bigger than the tiny one on my Camry so I think I'd want to change the filter more frequently. There is also the sludging issue to consider...
I'm curious: are you using synthetic in your Camry? If so, what oil change schedule are you following? The factory recommendation of 3000 mi seems excessively conservative and wasteful given the evidence that modern synthetic oil ought to be good for many times that distance.