I am now a firm believer in varnish. I ran my GMC 248 engine on 30 year old gas and it ran like a top for about an hour. I shut it off and let it sit for a few days, when I tried to start it again, it made some LOUD bangs and missed like crazy. I bent 4 push rods and stuck 4 valves. I ended up pulling the head and having a valve job done. It was a good $200.00+ lesson, $95.00 for a gasket set and $120.00 for the valve job (included new guides). I bought a new gas tank and replaced all the lines before starting it again. Don't believe the guys that say there is no problem with old gas, there is! Don't take a chance, drain it out!
