This engine does not burn much oil at all, maybe a quart/3K miles. Oil looks "normal" for an engine with 200K+. I.e., starts out looking like fresh oil and progresses to dark brown, never foamy or with air bubbles, no bad odors.
Previous owner replaced main bearings at about 160K. (He saved receipts and I have them) Are they shot again? Or is this something else?
Truck has had 33x9.5 tires for "a long time". Would running at low RPM (because of the larger diameter tires) in OD cause this?
Since this started I have not driven the truck much and always put the trans in neutral when coming to a stop.