I have an old (1962) MF35 tractor, with the Continental gas engine. Hour meter didn't work when I got it, was stopped at 1800 or so hours, got it working now. Engine is tired, but not worn out, makes some blue smoke when first started, but clears up as it heats up. So, what oil do you recommend? Have been using any 15w40 I can get, used some 10w30 that was handy last time, more smoke with the 10w30. I use it mostly for snow removal, cold weather use. Is there an additve I can use to help the rings seal better? Actually, I did a compression test and it was pretty good, close to 140#, which is the spec. Thanks!