I recently picked up an M54, ex fire department truck. The truck is in really nice shape, body is rust free and straight. I don’t think it saw any use after the department sold it, until I picked it up. I was able to get it running and it smokes likes a chimney. Grey/white. Usually only under load. I have yet to put any miles on it other than going a block in 3rd gear (no brakes). Idles good, slow and smooth. No blow by at all. Good oil pressure. Should I be concerned about this? Or could this go away after I am able to put some real miles on it. It has the C Whistler turbo if it matters.