I am currently in the process of thinking about changing oil weights (HD 40 to HD 60) due to the amount of miles on my power plant. The oil req. is 10w-30 at this point; however, I have noticed that this oil is too thin to use from now on. HD40 has the best qualities as I can see so far. First it coats the parts with a thick residue. Second, it stays in the piston rings longer that the thinner oils. Finally, it takes far more heat to break down that what I have used in the past.
What is the best oil weight I should use for my power plant?
Currently:
164K miles
3.8 Litre
4.5K Max RPM (Red Line)
No known odd noises, shakes, destablizations, chokes or other symtoms that might indicate a problem. Any suggestions? Ideas? Should I even go to HD60?
One more question, If you can possibly find out, What would happen IF I would put gear lube in a power plant? If you absolutley have to find out, try it on an old lawnmower. I cant seem to get mine fixed, other wise I would be able to tell you what happens.
Thanks,
Gear