Mobil Delvac 1300 15-40, The ZDDP is above 1300 ppm which is pretty high for standard oil. Mobil recommends it for all diesel but also for high performance gas engines. Shift very smooth and is all I have used in this bike for 16k, my last bike for 50k (only 50k because I tried Rotella Syn for about 35k) and the bike before that for 100k. Ride in 90-100 degree temps often w/o a problem