Gunk? Shine is an engine detailer and protector with a pleasant citrus scent that leaves your engine with a protective layer that makes future clean-up easier. When used as directed, it will also leave behind an attractive detailer's satin-like finish on underhood surfaces such as hoses, plastic and metal parts. Contains no silicones that can create a greasy, dust-collecting buildup. Use it on cars, trucks, tractors, boats, RV's, ATV's, compressors, generators, bicycles and motorcycles. Safe on most underhood rubber, plastic and paint when used as directed.