When you're collecting Whale Sperm Oil, isn't it best to find a friendly whale or do they automatically become friendly, as soon as the collecting starts? On a more serious, if less romantic note, neither oil nor grease "collect" dirt. Dirt will stick to either. Grease(my preference) will stay in place longer. the light oil used in old style air cleaners is there to give the dirt particles something to stick to, as they are brought through the filter by the air being sucked into the carburetor. They are not "attracted" by the oil. The important things, as many others have said, is to frequently clean off the old and replace with new, whether it's oil or grease. IMO, hinge pins or trunions ARE high stress areas because of the load placed on them(opening and closing the gun, cocking hammers and operating ejectors or extractors), not because of high RPMs or high heat.
