To biocide or not to biocide

There was a post talking about stabilzing oil, like if you start burning coal and have a tank of heating oil that may sit for months or years. Biocide was suggested to keep the oil from growing fungus or unknown salad components. Today I was buying some hydraulic fluid and saw a biocide poster on the wall. Seeing as they were selling it and I was standing right there, what better time to get some? I told the guy my intent and he said it was not what I wanted. He said biocide is for after you have fungus. He said what I wanted to stabilize the oil and prevent fungus is "Power Service Fuel Supplement". He then told me they don't sell it, but most auto parts places do. Seeing as he could have made a sale, but chose to send me someplace else, I tend to think he may be telling the truth!

there was a thread awhile back that the fuel will burn after years of storage.

I'm not an expert on this, but I do believe most heating oil delivered to the home already has a bacteria inhibiting chemical added to it, I don't know if the action of this inhibitor lessens over time.

I'm thinking adding a little kerosene (oz. per gal.) to the tank after the first year or so will help keep anything from "growing" & keep the oil "loose". If your tank has a drain plug on the bottom, I'd pull it to see how much water is in there also.......

There's a good biocide for marine applications (for boats with huge diesel tanks) made by Power Service. I'm pretty sure its called Bio Kleen. Any decent marine supply shop should have it, or you can order it online. It's a little pricey (a bottle is about $30.00) but 8 oz treats something like 300 gallons.

chances are that if it's a tank with any age at all, it probably has some algae in it, and it wouldn't hurt to treat it with biocide then add a bottle of powerservice yearly to maintain the fuel.