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Old gas in my 1995 Mazda Miata

My car has been sitting for about 8 months now, the radiator had to be replaced and it took us a while to afford one. Will I need to siphon out the old gas, or am I good to crank her up and go?

How much gas is in the tank?

Won’t hurt to try. Good to top it up with fresh gas soon. An alternative to siphoning, maybe easier and safer, is to disconnect a fuel line and run some hose into a gas can. Then jumper the fuel pump and let it run.

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Take the gas cap off and smell the gas. If it smells like gasoline, it’s OK. If it smells like varnish, it’s not. You might have to depress the flapper in the filler tube to let the odor out.


Gas that’s gone bad with age stinks! Not like gas usually smells, it’s much worse. If you smell it, you’ll know. I would consider putting in some dry-gas liquid if the gas seems to smell ok.

87 octane.

Your Miata engine isn’t a high compression engine,


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Not sure what you mean by burning too hot. Engine damage is not going to happen . The only downfall to 93 Octane is you spend more money then needed.
It would be wise to look in the manual for service items that may need to be done if you don’t have a service history.


I’ve gone > 18 months without buying gasoline, haven’t suffered from any of the pathologies the Cassandras on this site tell me I should. Buy a bottle of Iso-HEET to scavenge moisture and another of gas cleaner to dissolve varnish.

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Actually, higher octane gas burns “cooler” than lower octane gas.

Once you get the octane issue resolved you’ll still need an owner’s manual if you plan to keep driving this car. Suggest to stop by a Mazda dealership shop when they aren’t overly busy and ask them if they know how to find a pdf version online. If not, ask if they can search other dealership’s stock and find a paper or CD ROM copy available in NOS. You local public library may have a Chilton’s or Haynes repair manual for the car also. Sometimes they’ll list the octane recommendations. It’s weird there’s no simple online path to the manual.

You need to look under the lid over the gas cap. If there is no sticker there, use regular. If there is a sticker, use what they tell you.

Why did you repost the same thing with what appears to be Spam . Remove the link before you get flagged . Also did you not read the Reponses ?