Tractor Oil

It's a bit of a misconception that detergent oil will loosen up 50 years of crud in your engine and immediately clog your filter & ruin your engine.

What detergent oil WILL do is keep contaminants (dirt, carbon from exhaust blow-by, etc.) in suspension better than non-detergent oil, giving your filter a much better shot at filtering them out.

Where you will have a problem in an older engine is when you try some of those motor flush products, or "run it with kerosene in the crankcase" like you hear people saying sometimes. That is definitely something you don't want to do with an older engine.

Bottom line, detergent oil is the way to go...Use it !

I believe that the crud around the piston rings will come loose and you MIGHT start burning oil if your rings are worn out and masked by the crud....may not. May run better if you had a stuck ring and the detergent oil freed it up so that it could function properly.

As far as the majority of the rest of it, I think that if the detergent attacks it, it will be a thin layer at a time and doubt that any passages will become clogged. You could have a very rapid contamination (dirty)of your oil Dave mentioned, but I personally would try it before I tore into somehting....ain't broke, don't fix it....have gotten myself into more unnecessary jams by not following that simple rule. You will have watch the oil filter. If a lot of crud comes off fast it could plug the filter and you would have to change it frequently but the oil would have to be black before this became a problem....as I see it.

Good luck

Mark