john robert bould said:By far the safest method of cleaning is DRY ICE blasting....I have seen a demo on the Internet....
Dry ice is good for removing dirt, oily crust etc. It does not really take away this burnt-in oil surface residue. The guy who soda-blasted my engine parts also offers dry ice blasting as well but strongly recommended soda. Cheaper and better results.
Best regards,
Tim