The Ford Barn

Tom Wesenberg · 06-15-2015, 08:44 AM

I've read about guys adding a quart of diesel to corn crap gas to help with vapor lock. I haven't tried it yet, but always thought it was a good idea, and should also help the gas tank to not rust. I just came across this on another car site:

"I run a testing laboratory at an oil refinery. Gasoline composition varies quite a bit from season to season ( Thank you EPA). During the summer months the gasoline formulation tends to have more of the "light ends" which lowers the initial boiling point. This is primarily from the addition of butane. Butane is cheap and boosts octane so refiners add as much as they can during the EPA defined season.
Gasoline is not like water. Water is a pure substance that always boils @ 212 F ( at standard temperature and pressure). Gasoline is a mixture and it boils off 1 component at a time. During the summer you will find that it starts to boil around ambient temperature and as low as 70 F. It continues to boil off the lighter components until they are gone. So if you distill gasoline it starts to boil at very low temperatures and continues to boil until the heaviest components boil at about 437 F.
Adding diesel to the tank will not affect the IBP ( initial boiling point). It only serves raise the final boiling point (FBP). Raising the FPB ends up leaving a residue which coats the surfaces and helps protect from rust, etc.
Pressuring your gas tank effectively raises the IBP so that your gas does not boil in the tank. The higher the pressure, the higher the IBP. If your tank is not pressurized then your only solution is to isolate and insulate."

06-15-2015, 08:44 AM	#1
Tom Wesenberg Senior Member Join Date: May 2010 Location: Mpls, MN Posts: 27,582	Adding Diesel to Gas Helps Fight Rust I've read about guys adding a quart of diesel to corn crap gas to help with vapor lock. I haven't tried it yet, but always thought it was a good idea, and should also help the gas tank to not rust. I just came across this on another car site: "I run a testing laboratory at an oil refinery. Gasoline composition varies quite a bit from season to season ( Thank you EPA). During the summer months the gasoline formulation tends to have more of the "light ends" which lowers the initial boiling point. This is primarily from the addition of butane. Butane is cheap and boosts octane so refiners add as much as they can during the EPA defined season. Gasoline is not like water. Water is a pure substance that always boils @ 212 F ( at standard temperature and pressure). Gasoline is a mixture and it boils off 1 component at a time. During the summer you will find that it starts to boil around ambient temperature and as low as 70 F. It continues to boil off the lighter components until they are gone. So if you distill gasoline it starts to boil at very low temperatures and continues to boil until the heaviest components boil at about 437 F. Adding diesel to the tank will not affect the IBP ( initial boiling point). It only serves raise the final boiling point (FBP). Raising the FPB ends up leaving a residue which coats the surfaces and helps protect from rust, etc. Pressuring your gas tank effectively raises the IBP so that your gas does not boil in the tank. The higher the pressure, the higher the IBP. If your tank is not pressurized then your only solution is to isolate and insulate."