depends what I do. I often use the left on the computer mouse. On the car wheel it's either the left or both. Writing I can use both, but prefer right. I'm pretty sure that's mostly muscle and mental memory.
Using a hammer is interesting with the left. You hold the nail with the right. Don't do that often. But a bit of fun. Indicates I am right handed, although do fairly well. It's not clear if it's more challenging due to lack of practice or mental deficiency. I'd say right handed, as of now. Keep the possibility open that this will change.