Another vote for Phillips X/C and CamGuard. I typically buy CamGuard from Aircraft Spruce but this year I picked up a few pints at Oshkosh to save a few bucks on shipping.
I just found this and it is cheaper than what I have been paying for Phillips 20/50 anywhere else, because shipping is included. They have a 4 gallon case that works out to $5.90 a quart.
