Fuel question

[printman71]

1987 Mercury 2.4, 175 horsepower, serial # B242796
Pre mix oil (Using premium plus) and gas
OK to use 87 Ethanol Free or better to use 89 or 91 with ethanol and add stabilizer?
Not a lot of local choices for anything other than 87 ethanol free around here.

[leonreno]

87 is what your motor uses so 87 ethanol free would be great. There is info on fuel selection in the faq

[JOE54]

^^^^^^^+1

[printman71]

Thanks,I didn't see this covered, so I overlooked.
For some reason, I thought the 2.4 was a higher performance engine and needed above 87 octane.

[SilverFox579]

It's in this FAQ topic - Oil, Battery, Spark Plugs, Fuel and Fuel Additive Recommendations


Don't take references to minimum octane to mean higher is better, it is not, it simply means no less than the advised octane.

-All models- MAXIMUM ETHANOL CONTENT: 10%. Ethanol content may adversly affect engine performance.
-See "Mercury's View of Ethanol" on Sherm's board at:Mercurys take on Ethanol blended fuel
-Standard Opti's (ALL) 87 Octane MINIMUM.
-Standard 2-stroke Carb/EFI Models: 87 Octane MINIMUM.
-XS, XB or Racing PRIOR to 2006- CONSULT OWNER'S MANUAL! Most require High-Test!
-ProXS and 250XS 2006-UP: 87 Octane MINIMUM. IF poor idle quality occurs, could can try 89 Octane (mid-grade) to see if quality improves.
-300XS- Consult Owner's Manual. High Grade (minimum 91 Octane) fuel required!

[leonreno]

Here is the fuel selection guide from the faq:

Fuel Selection:

Make your fuel selections based on the following criteria, IN THE FOLLOWING ORDER:

-High Traffic, Top-Tier (Name Brand) Fuel
-Appropriate Octane Rating (see above info)
-Lowest possible ethanol content (NEVER to exceed 10%).
-While it may be preferable to utilize a fuel that contains lower (or no) ethanol, use of fuels that are SUBSTANTIALLY higher octane can result in decreased performance, decreased fuel economy, and potential for carbon buildup. Higher octane fuels burn SLOWER and COOLER.

[printman71]

Thanks for the research. Had it been a snake, it would have bit me.

[TKress]

Leon, what do you consider substantially higher octane? The only available non ethanol fuel locally is 91 octane. I am guessing it is OK but I like to be sure. Thanks.

[silverbullet02]

Leon, what do you consider substantially higher octane? The only available non ethanol fuel locally is 91 octane. I am guessing it is OK but I like to be sure. Thanks.

Won’t hurt a thing.

[EuropeanAM]

Leon, what do you consider substantially higher octane? The only available non ethanol fuel locally is 91 octane. I am guessing it is OK but I like to be sure. Thanks.

"Substantially Higher" would be basically any fuel more than 2 octane points above what the engine was designed and calibrated to run with.