Old Gas

[40 Deluxe]

Originally Posted by Keith True

There have been gas problems since there has been gas.I can't really say that I see more gas problems than I did in the 70's.i was always pulling out big blobs of rust that were supposed to be sending units.In 1978 I bought a 68 GMC ramp truck with a V6 in it.It had been sitting for about 3 years.I got it up and running,headed out to the road and all kinds of fun things happened.Valves stuck shut,bent a bunch of pushrods,pulled some rocker studs right out of the head.i parked my Tudor in the cellar in 06,to put an interior in it.I just got it out again last week.It had over 1/2 tank of bad gas in it.I just drove it until I burned it off.You could smell me all over town driving around.I know some people like to remove the booze from their fuel,but I don't see the point.The people at the tank farm I hauled out of said that the gas is around 77-78 octane until the ethanol is added.They said the non-ethanol is formulated differently,it is NOT the same gas that they just don't add to.I thought it was the same gas,just with the alcohol added later.They set me straight on that at the tank farm.

Ken, you bring up a good point! Some old gas, as it evaporates in the tank, leaves behind a varnish -like residue. Fresh gas will dissolve this stuff, and it will end up in the combustion chambers. However, it does not burn completely and instead deposits itself on the exhaust valve stems. It is extremely sticky and WILL seize the exhaust valves, either open or shut.
Other old gas will work just fine. I think it depends on how much gas evaporated out of the tank, how long it sat, as well as the formulation of the gas, which varies according season and what part of the country it came from. After some bad experiences, I say drain and flush the tank before attempting to start on old gas. Much easier than dismantling the valve train like I had to do on my '40.