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Hey Engine Man: How Do I Get Rid of the Sticky Goop in a Gas Tank?

Successful Farming Engine Man Ray Bohacz has engine grease and field dirt under his fingernails from a life spent repairing vehicles and running a farm. When he’s not busy in the shop, he’s working on maintenance articles and videos for Successful Farming magazine and answering questions from readers. The following is a letter the Engine Man received from the Hill Family:

I have an old Ford 800 gas tank with sticky sludge and rust particles in the bottom. The tank is in good shape. Do you know of any way to get the sticky goop out of the bottom? It’​s probably caused from the ethanol in gasoline.

Response from the Engine Man:
The best thing to do is to drain and remove the fuel tank and purchase one of the many excellent gas tank coating kits. This will end the internal rust problem for good. POR-15 and Eastwood, along with many other companies, offer these kits.

Depending on the kit you buy, you will need to follow their instructions for cleaning the tank internally to accept the coating. This will depend on the chemical composition of the coating.

For the most part, you can usually put a high concentration of a solvent like Simple Green with water and let it soak and then pressure wash the tank via the sending unit access. If the deposits are more stubborn, then paint thinner usually does a good job if allowed to work for a while.

If you follow this clean-out procedure, then the coating works very well. 

As an aside, I doubt very much that the ethanol had anything to do with the sludge formation; it is just built up from years of use.

Do you have a maintenance question? Email Ray Bohacz at


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