I sealed my MGT 8.0 engine and my Pro .15 and what a difference. Used blue rtv sealant and green slime to seal it. I've only sealed these two because these were giving me issues. Once my K5.9 gives me trouble I'll seal that one too. So far the two OS engines I have and the Gs engine I have are fine. Just wanted to say thank you to the RCNT community for really stressing this in all the posts that state an engine is running lean.