Best oil Visc and brand
 

What viscosity should I be using, I've been putting in 5w30 Mobil 1, I'm in Buffalo, NY.
Have 32k on my 2002 Prius.

Re: Best oil Visc and brand
 

5w30 is the correct weight for the Prius. I do not recommend deviating from that. Toyota wouldn't either.

You are using Mobil1. That is a quality synthetic. I doubt you can find a better one out there for less money. Some folks are using Royal Purple, others are using Asmoil, but they both cost more, and using the normal Prius oil change intervals, I doubt that the extra cost will provide any extra protection. Frankly, the engine oil at 4000 miles on my 05 is so visibily clean that I wonder about the length of the replacement interval, but I do it then anyway. I have not had an oil anaylsis done, and probably won't, but I'm sure there is stuff in that oil that you wouldn't want in the engine any longer than necessary, even if soot is not one of the things saturating the oil.

I'd advise you to keep doing what you are doing. Just avoid Fram oil filters. They aren't so hot. Use Toyota, Purolator, Wix or Bosch filters instead.