Engine Oil

My SD220 is freshly rebuilt but it is lightly leaking out of the rear main rope seal. I was thinking of going 20w50 to slow the leak which isn't a lot to begin with but figured that's too heavy. Would you agree? Do you think I should go with 10w40 as the middle ground to not be too heavy but still help slow the leak?

I'm not pulling the engine to fix the leak. I learned years ago when buying old tractors a little leak won't hurt anything as long as you keep an eye on it.

Have to say I've not seen viscosity have much of an effect either way on a rear main leak. Fresh overhaul I'd be running 10W-30 or 10W-40 depending on outside temp. Flow is more important than anything.
either live with it or fix it right.

I’ll go with 10w30 then

I think Old IHC had some HD DNA. The two models liked to mark their spots like a dog. I had 15/40 on hand, so that is what the Old SD220 got.
There was a time when I had wired an adult diaper to the bottom/back of the engine. I would change the diaper once a week. The deceased neighbor's wife gave me the diaper supply. I needed the diaper so I could drive the SD220 into Vancouver and not get a ticket for the leak.

My SD220 is freshly rebuilt but it is lightly leaking out of the rear main rope seal. I was thinking of going 20w50 to slow the leak which isn't a lot to begin with but figured that's too heavy. Would you agree? Do you think I should go with 10w40 as the middle ground to not be too heavy but still help slow the leak?

I'm not pulling the engine to fix the leak. I learned years ago when buying old tractors a little leak won't hurt anything as long as you keep an eye on it.

I have the exact same issue on a rebuild of SD240. I am not pulling the engine either. I don't think oil weight will help the situation. I think my problem is the sealing around the rear main bearing cap rather than the rope itself which could possibly be dealt with without pulling the engine. Not sure it is worth the effort. Just changed from 10-30 to 15-40 but not for leak reason but because that is what I use in other toys.
Dennis

I like the diaper idea , a red rag looks cleaner..

I used start up oil from Joe Gibbs I think , and now use racing oil for the zinc in it , sounds like you need to tighten up the rope