I've used Eastwood's "Chassis Clean" on two engine blocks with great results. Couldn't be happier with the stuff. When done, I had absolutely no residue and no issue with primer or paint lifting. Its cheap and in an aerosol can so you can spray blast it. Spray, scrub with toothbrush, repeat. Then wipe down with a clean rag. I love this stuff. I use it to clean all kinds of things. It will even take paint and grease off plastic without hurting the plastic if used carefully.

Common sense and caution are factors which cannot be built into any product. These must be supplied by the operator.