I always use enamel reducer first to wash bodies before any sanding, then a very hard scrubbing, using something like Tide or other good soap... as far as a new gel coat body sanding, I start with about a #60 open coat paper dry, as it (primer) needs something good to hang on to, but who knows? maybe now days things are done differently, but I did this for years and it works good for me, as that is how my body maker told me to do it... Good luck and take your time... have fun no matter

Gas has oil in it...