Wow, I have a 09 Corolla that specifies 0w20 or 5w20, and I've been running some 5w20, but mostly 5w30 or 0w30 M1 with no problems at all. Does the 2010 actually have a different engine than the 09's? If it's the same, I wouldn't hesitate to use 5w20 if it were my car, especially in the summer. I can't believe Toyota would spec a synthetic only oil for such a common automobile. The new Camry's are really nice, but it's not like it's a Ferrari, you shouldn't have to use synthetic if you don't want to. There are going to be alot of [censored] off soccer moms when they take their car in for a $60 oil change when their old Camry was $25!