By indifferent I mean not sticking to one brand of oil and at times using house brand names.But alway a Wix or Napa filter.The Cherokee PVC system can plug up and that creates a mess under the valve cover.
A quick story;back many years ago I worked part time at a school bus garage.At the time the Fleet was about 100 buses,mostly early 70's Fords and IHC.They average about 10,000 miles each during the school year.They were gas V-8 engines.I was surprised to learn the oil was rarely changed,I mean once a year during the summer.Back in the late 70's ,running oil for 10,000 miles in somewhat heavy duty bus use sounded insane.It was sludge city back then in car engines for guys who remember.But when valve covers were pulled to replace leaking gaskets,the heads were really clean inside.The garage manager said the engines ran hard and hot so they stayed clean.The buses last about 9 years and so did the engines. Maybe if the oil was changed more often they would last longer.But since the bus was scrapped ,who cared if the engine still had life in it? And yes,a few engines started smoking or lost oil pressure before their time but never could say it was because of the lack of oil changes.
