All Chevy 216/235 truck engines have been painted Blue/Gray. However, there is no described formula that we know of. Each assembly factory seemed to have mixed their own batch and when that ran out, mixed another that didn’t always match. This color has been debated across this forum and the internet for years. Here is a
link to a previous discussion on this forum. I used Bill Hirsch engine paint which can be painted with a brush, and I’m pleased with the color.