Gas shelf life - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**Michael D** · 01-01-2025, 12:21 AM

My truck has sat for over a year with a nearly full tank of 91 octane.
So I was planning to purge the tank low enough to get rid of bout 90% of the current gas and refill it with new but do I really need to?
How long does 91 octane or any really last. There is no humidity here in Az which helps.

I'm asking because I recently learned we have a place in town that will take old gas for free. Ha, that's a business I should look into.
It will be road worthy very soon and that old gas running through the fuel system and the possibility of screwing up something has been on my mind.
FWIW, the gas is feeding an injected LS LQ9, not carburated.

01-01-2025, 12:21 AM	#1
Michael D Junior Member Join Date: Mar 2010 Location: AZ Posts: 93	Gas shelf life My truck has sat for over a year with a nearly full tank of 91 octane. So I was planning to purge the tank low enough to get rid of bout 90% of the current gas and refill it with new but do I really need to? How long does 91 octane or any really last. There is no humidity here in Az which helps. I'm asking because I recently learned we have a place in town that will take old gas for free. Ha, that's a business I should look into. It will be road worthy very soon and that old gas running through the fuel system and the possibility of screwing up something has been on my mind. FWIW, the gas is feeding an injected LS LQ9, not carburated.



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