I used Solder Seal's "Gunk Engine Bright" on the Moose Truck some time back. I forget how it happened, but it started out that I wasn't really looking to wash the engine, but I spilled something, and then one thing led to another, and the next thing you know I'm hosing it down. I like the way an engine smells after it's been Gunked. I did avoid spraying the IP all together, but I think in reality as long as you don't turn the crank at all until the entire engine has returned to atmospheric temperature, I don't think there is too much risk. One thing is for sure, having had an injection pump on Lady Moose that needed a cold shower to get it started, they definitly are incredibly sensitive to temperature change.