39 B Here's what an oil change brought me...

39 B with unknown history. Got it running after it sat for a couple years since it last ran according to the last owner it was running good but the magneto went out.

A fresh mag and gas it fired right up on the second hand crank. New plug, wires and moved it around the yard for about 10 minutes getting it warm. No smoke and no leaks. Pulled it in the garage and drained the oil which was full but black and thin.

New 20w50 and a fresh filter....would not start....ended up pull starting it and it is blowing blue oil smoke. Not tons but it is vsible. Runs okay but will not start without pulling it and when I increase throttle it lets go with a puff of blue.

Gona do a compression test this weekend but I am limited in my scope of ideas...rings or valves? Did the fresh oil clean away or stick something. What say you mechanic guys that have BTDT. Coincidence? Any methods to help ID the needed fix? Leakdown test on the cylinders? The not starting by hand crank seems odd. It is timed and runs okay once running but for the oil smoke.

Appreciate your thoughts. I am gonna save this one so it is going to get fixed one way or another.

First 20w-50 oil is not doing that engine any good if you study lubrication and oil flow.
I would suggest 30w or 10w-30.
The piston rings are probably froze.
Try running 3 quarts of oil with one quart Marvel Mystery oil.
They will probably free up the longer you run the engine.
I had a C that set 24 years. Piston rings were froze. After a month of on and off use they were free and no smoke.
The frozen rings will lower the compression and also cause oil to get by the rings and make it hard to start with the hand crank and smoke alot when it is running..
The valves that were open while the tractor set probably have rusted valve seats from moisture.

PS: I would say the oil change did not cause the new engine problem. Coincidental.

With what you said and it was mine I would change to 15-30 oil and add a can of Seafoam. They call for 1/2 can in the crankcase and the other half in the gas. I have in the past put a full can in both.
It will get in and under rings. I have a Farmall C that needs an overhaul due to setting many years that smokes like a coal burner every spring. I add a can of Seafoam after changing number four spark plug and after about a half an hour of work it will only smoke a bit on startup and then clear right up.

Well first off you knew it had not run in years but yet you start it up with dry cylinders mistake #1. Me I would have filled the cylinders with ATF and let it sit at least a few days so as to clean and lube the cylinders and loosen up the ring which where probably sticking. As for the multi weight oil that is mistake #2 all multi weight oils and what the lower number is and have additives to make it work like the heavier weight oil. Me I would use a straight 30 or 4o oil in and get rid of the smoke problem. As for starting go back to the first thing I think you should have done and do it now so as to loosened up the stuck rings which is has

My 39 B did the same thing. It was a regular runner tho.

Bought the tractor and drove it home 8 mi or so. Oil looked dirty so I changed it- bad idea..... Im thinking I shoulda used a non detergent oil.

Old, thanks for pointing out my failures. Good thing too as I sought it out! When I searched the archives, I was able to see that you have recommended the ATF soak to nearly everyone you respond to for a host of issues, yet I failed to do so. Should of anticipated my ineptitude sooner. Never again now that I have some useful insight and experience.

Jeff and Dick, thanks for the info and I am changing the oil after the soak with different viscosity oil and mixing in some MMO and/or Sea Foam. Appreciate the help and advice.

I think the same way rasman57 does. Just keep changing oil and it will wash clean. If your tractor has a magneto, check and make sure there is a sharp click noise coming from the mag when you turn it over by hand. When you ran it for the first time the coupler might have stuck open in the magneto.