Does anyone have technical information as to why I shouldn't, instead if "I wouldn't use it" or "Use this instead". I know what oil to use and the recommended oil for her car I'm asking is it possible to run said oil without running into any issues since I have a drum of it for my bikes.
Originally Posted By: timeau
15w40 for motorcycles and 15w40 for vehicles are two different oils. If this is not a regular Rotella, do not use it. Regular Rotella 15w40 would be great for summer, I used to have such car, it prefers thick 40-grade oils.
That's not correct, you can use many types of motorcycle oils inside of cars and vice-versa without any problems. I wouldn't recommend it since motorcycle oil is usually a lot more expensive. Some older motorcycles, mainly the "chopper" style type of bikes don't like some friction modifiers that car oils carry. That being said, Shell doesn't make a motorcycle oil but I use it in my bikes since it's just as good if not better than the leading performance oils such as Motul and Amsoil for a fraction of the price. You say thick grade oils are fine while the other two posters disagree, which one is it?