PO of my 81 300D had been getting its oil changed at one of the local "oil change specialty" shops for several years. When I changed its oil a couple of days after I bought the car about 2+ years ago, I found the oil filter DRY - obviously had not been changed in years. Air filter was grossly too small and completely ineffective because of air bypassing it. PO had been paying the oil change shop for new filters at every oil change.