These photos show an engine that was subjected to Pennzoil over and over again........
Although their racing oil was good. I tried castrol in a 83 or 5 Mazda as it was on sale and money was tight. Within two oil changes (2500 apart) I could see varnish forming when I took the fill cap off the valve cover. I went back to valvoline and have been using it since
Although their racing oil was good. I tried castrol in a 83 or 5 Mazda as it was on sale and money was tight. Within two oil changes (2500 apart) I could see varnish forming when I took the fill cap off the valve cover. I went back to valvoline and have been using it since 
