My '50 3100 had the original 216 and definatley had an oil filter.. it was a can type on the drivers side of the engine with a 3/4" head in the center.
I pulled the plug out of the oil pan and let it drain, and then opened up the filter can by simply loosning the 3/4" bolt head. The "lid" of the can just lifts off once the bolt is loose, and inside the "can" sits the filter.
My '46 2 ton with the original 235 engine did NOT have a filter.
Like OldSub said, it isn't any different than changing the oil in modern cars.. drain the old oil, put the plug back in the pan, and fill with fresh clean oil.
Only difference would be the way the oil filter (if yours has one) looks like, and being able to recognise it.
