I have and SRT-4 and a Saturn Redline I run mobile1 5-30 in both and thats what DC and GM say to run. 5-30,10-40 and so one are multi-viscosity oils. Meaning they at diffrent temps they show cariteristices of the diffrent wieghts they are. Smaller numbers are thinner bigger are thicker. Then small number stays thin and easy to pump in the cold and the hight number will take heat better. Thats just a generalization there is a ton of science behind it. Any way 5-30 mobile1 will do you fine.