big red.. its pretty much the ***. it doesnt corrode your aluminum or eat your paint, but it takes every spec of grease off. i used it to clean my engine bay last time my engine was out, and i thought nothing was gonna clean 100k miles of exhaust and oil leaks. but the engine room looks pretty much brand new after i sprayed it a few times and let it soak. and it works wonders on crusty heads and blocks. inside and out. my all time favorite cleaning tool tho, is my solvent tank. great invention.