New merc 115 fourstroke

[Bassakwards]

Just bought a new Ranger RT 188 with a 115 4s. Anything special I need to know about these motors? I only use ethanol free gas, is 87 ok? Should I use any fuel additives? My last boat had a Yamaha so I'm new to Mercury. What is required during the break in process?

[EuropeanAM]

Great motors. For fuel additives, I recomment 87 Octane, with the following additives:

1oz Mercury Quickare
1oz Mercury Quickleen
-------------------------
Per 5 Gallons of fuel.

Follow the break-in recommendations found in your Engine Owner's Manual for best results.

[Bassakwards]

Ok thanks Don.

[Bassakwards]

I have an almost full bottle of Sta-Bil, is that ok to use up before I go with the Quickare?

[2500]

Blue or red Sta bil

[Bassakwards]

Blue marine sta bil

[2500]

Yes but get Merc stuff next

[EuropeanAM]

+1

[Bassakwards]

Thanks guys

[Ohio Archer]

Posts 10-12 (below) pertain to recommendations based on fuels OUTSIDE the US. Ratings shown are from a different (RON) rating method than is used in the US.

I know this is old but it pertains to my 115 hp 4 stroke.

Owner's manual states 87 octane as does the Merc 115 outboard page. BUT, the Merc Service and Maintenace page shows a minimum of 91:

MERCURY & MARINER FUEL RECOMMENDATIONS
Use a major brand of automotive unleaded petrol (ULP) with a minimum posted octane rating of 91
These recommendations apply to Mercury and Mariner 2-Stroke, 4-Stroke, Verado and OptiMax models unless specified otherwise (ref to "Notes & Exceptions" following)

http://mercurymarine.sv7076.si-serve...outboards.aspx

Why the difference and which one is right?

BTW, already using the Quickare and Quickleen combo.

[jethro1]

I know this is old but it pertains to my 115 hp 4 stroke.

Owner's manual states 87 octane as does the Merc 115 outboard page. BUT, the Merc Service and Maintenace page shows a minimum of 91:

http://mercurymarine.sv7076.si-serve...outboards.aspx

Why the difference and which one is right?

BTW, already using the Quickare and Quickleen combo.

Given the use of the word "petrol" in the linked document, it would appear that this is addressing Mercury/Marine models that are used outside of the USA. Outside of the USA the octane rating of gasoline is calculated differently. If you have a USA model motor, and are buying gasoline here in the US, follow what is written in your owner's manual for your specific model.

In a nutshell "Because of the 8 to 12 octane number difference between RON and MON noted above, the AKI (anti knock index) shown in Canada and the United States is 4 to 6 octane numbers lower than elsewhere in the world for the same fuel."

You can read more about the octane differences here

https://en.wikipedia.org/wiki/Octane_rating

[Ohio Archer]

I was doing a search on octane and merc outboards. Read about the differences between RON and (R+M)/2. Found the above link but didn't see it was from Australia. Doesn't say that unless you go to the "Contact" page. Since the website date was 2017 and my engine is a 2015 wasn't sure if the required fuel had changed. And the 90 rating didn't reflect RON.

Didn't key in on petrol either as it's all the same to me. Petrol, fuel, gas, etc.

So, 87 it is.