Jump to content

Recommended Posts

I found the post of ethanol free gas but what octane should I use in this new 4 stroke Merc ? 

(No I don't have docs on my boat yet)

 

Thanks in adv...

Share this post


Link to post
Share on other sites

Check the manual. Probably recommends 87

Share this post


Link to post
Share on other sites

I have the Merc 150 four stroke and run ethanol free 87. No issues and its been 4 years.  

  • Like 1

Share this post


Link to post
Share on other sites

I agree with 87. Most everything I have read says your wasting money if you use over 87 octane in a boat motor but I would call Mercury or wait until you get the docs on your motor.

Share this post


Link to post
Share on other sites

I run two 4-stroke Mercs. 87 octane minimum with cleaners is preferred per manual. However, even better as stated in manual is ethanol free. I run ethanol free whenever I can get it regardless of octane; usually 90 or 91 around here. If you have to use alcohol enhanced gas, manual states 10% ethanol or less, or 5% methanol or less.

  • Like 1

Share this post


Link to post
Share on other sites

I'm running non-ethanol gas in my 4 stroke Suzuki, and only octane I can find is 90, so that's what it gets. Better 90 octane non-ethanol, than 87 with ethanol!:thumbsup:

  • Like 1

Share this post


Link to post
Share on other sites

I have a 2018 Merc 90.  Manual says 87 ethanol free or 90 with 10% ethanol.  I only run ethanol free gas. There are plenty of ethanol-free stations in middle TN.  

  • Like 1

Share this post


Link to post
Share on other sites

I always run NON ethanol gasoline.  Around here 91 octane is the only way it comes.  I also add Quickleen and Quick Care to all of the gasoline.  I doesn't cost much and can save a bunch.

Share this post


Link to post
Share on other sites

Check with your dealer!

Back in Oct 2018, this year, E15 gasoline was approved to replace E10. The impact is 10% ethanol vs 15% ethanol, an increase of 5% regardless of octane. The ethanol is blended at the refinery can add up to 15% and label it E15 depending on supply and demand of ethanol. E15 can be 1% ethanol or anything inbetween up to 15%. E0 is ethanol free gasoline.

Higher octane doesn't damage the 4 stroke power head nor does ethanol. Higher octane lowers pre detonation with 4 stroke engines with high compression pistons. Ethanol acts as a detergent that can affect fuel lines and filters, and may run leaner unless the injectors are designed for higher % ethanol.

I have always used 91 octane gasoline with my 2 stroke OB's unless racing then used 140 oct aviation gasoline, cleaner burning fuel.

Tom

Share this post


Link to post
Share on other sites

I have merc pro xs manual says 87-91 ethanol free if possible. Up my way 87/89 have up to 10% ethanol. I was having some issues with poor idle and performance with th 87 even tho I treat it and only fill boat with what I will use so the gas doesn't sit more then a week. After switching to 91 the motor has never run better...

  • Like 1

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.

  • fishing forum

    fishing

    fishing forum

    fishing rods

    fishing reels

    fishing

    fishing

    bass fish

    fish for bass
    fish

×