How long fuel oil good for?

[Max W]

Is there a limit on how long fuel oil will keep without causing burner or other problems? I never considered a ‘best by’ date for heating oil but have been reading conflicting statements on how long fuel oil can be used. Some, mostly oil dealer sites, say two years. Another site reads ten yrs under ideal conditions.

I last bought oil in Feb. ‘22, a 100 gal. Right now the 275 gal tank in the cellar is better than half full. Got a new tank later in ‘22 and transferred the oil from the old tank which was rusting on the inside, as they do, and it had started leaking. (There’s a cautionary tale that I posted at the time. The story only ended without disaster by some real luck.) Some older oil must still be mixed in but I’m sure it all of it must have been filtered transferring to the contractor’s holding tank and then to the new one. At first I wondered if I should start running the boiler to use it down but I think I am fine right now. Looking further down the road my question remains

With two new 9000k mini splits installed upstairs in December along with our main floor 15000k we have been running on heat pumps alone and have been comfortable. This very cold stretch has made it a great trial. I’m not ready to give up the boiler but does that require some kind of maintaining of whatever oil I have?

 

[all night moe]

There is an additive for diesel that has been sitting and subject to bacterial growth. Diesel and fuel oil are the same. Heating oil is just dyed. Woudn't hurt.... add the additive and change the filter a couple times more than usual for any rust particles.

 

[johneh]

Add Diesel Conditioner once a year and you should be good
When we finally got off oil. The tank was half full of 10-year-old
number 2 furnace oil. The dealer took it out and checked it. I guess
it was OK because he paid me for it. Pulled old wood/oil combination
and put in wood/propane combination.

 

[Turbo89]

Home heating oil is just like diesel (this is why the DOT “dips” big rigs, looking for color, lol). I’ve started diesel trucks that have sat for 10yrs with the fuel in there tank; so it’s pretty shelf stable.

The issues are bacteria growth, water and centane droops with time. You can buy centane boost (id probably toss a bottle in now after 2 years), and you can test for bacteria (there’s an addictive to fix that) and water.

Changing filters periodically is a good idea too, there really cheap and easy to put in.