Haha Cyberprius. It's not the 710 cap, it's the oil filler cap. The 710 you see is actually the grade of oil to use. So next time you go to the parts shop and ask for oil for your Prius, the guy may try to hand you some 5-30 or even 0-20 grade. However you should push it back to them and say, "No it requires 7-10 grade, I read it on the filler cap". Just a heads up for you CP.
Reminds me of a friend who asked for help putting "710" in her BMW. She said there were a bunch of places to fill it.. found out she was referring to all the different caps(brake, P/S, coolant, etc) Doh!