Barry and Martin bring up good points. Barry will always bring up something you never knew before, which is great for the forum. I personally wouldn't use mineral spirits cause using it is the last thing you put on your car(besides tack rag) before putting on the most expensive thing, paint. So my issue would be residue and evaporation time. When you wipe off your grease and wax there's still a tad there to be evaporated so you're relying on it to be gone with no residue afterwards. That's where the problem would be for me. It's just not worth the few dollars you can save. I could be wrong though, maybe it works great as a grease and wax remover, but I wouldn't go testing it. I'd rather let you and others test and tell me about it later.