I use AMSOIL Full Synthetic. I go the 7,500 between changes. It is available in 5W-20.

Here's a tip with Synthetic. If you have a leak, a drip, seepage of ANY kind, Synthetic will make it worse. I speak from experience. Even on my motorcycle, if I have any type of Dino oil seeping, Synthetic will be twice as bad, as it really flows.

Don’t let this deter you from using Synthetic, just be aware.

If you sign up for Amsoil’s “Preferred Customer” plan (I think I pay $20 a year) you get a hell of a discount. And with the cars and motorcycles I use it in, it pays for itself.