Do a search on WHAT OIL or try BEST OIL. And make sure you have about 3 hours to read through it all! people are using every oil under the sun except automotive oil with the "energy conserving" stamp on the jug. The most commonly used oils seem to be the diesel 15W-40's and synthetic 5w-50, 10w-40, 10w-50 or whatever you prefer. I've been running mobile1 5w-50 from canadian tire and delo15w-40 made by cheveron.