[Dave in MN]

I was a big fan of using Glyptol inside the engine until I had the opportunity to open an engine overheated by running low on coolant. The enamel was coming off the hottest areas of the block in sheets. I have not used it since.
Good Day!

Update after reading later postings:
Well, the insides sure look nice when they are painted that deep rich color don't they? It sure gives the impression that someone really cares about their work. For some, it may be about better oil movement but for me it was about the "Look". But indulge me...read on. My original post was short, I should have further explained my reason for eliminating the use of interior sealers. It was not just because an engine may overheat and then the seal would peel. In the engine I describe above, the operating temps were hot enough that the new Snyder's 5.5:1 head cracked and the pistons scuffed so I know it was very hot. As I was repairing the heat damage, and removing every bit of loose and remaining well-bonded Glyptol, it became crystal clear to me that I was possibly inviting future problems. Should any sealer peel from the valve chamber surface, for any reason...overheating or not, it would likely end up in the main bearings or blocking oil from flowing through the supply tubes to the main bearings. I just made a risk to benefit judgment and decided to eliminate any further use of interior sealers. Right or wrong...educated or knee-jerk reaction...it really doesn't matter because it's JMO.
My Rebuilds, My reputation, My opinion...My call!

ps: I fell off a roof once because I was so accustomed to walking near the edge that I let my guard down. It wasn't a high roof but I had time to decide before I even hit the ground that it was not going to happen again. Painting the insides of engines seems to me to be like walking near the edge for no real important reason and not paying attention to the perils.