OT can I use E15 in my outboard?

RayP(MI)

Well-known Member
Inherited a '70s vintage outboard runabout from my son when he passed in October. Actually I advanced him the money and he never paid me back so I guess its mine now. Anyway I can't find premix gas, and recreational is hard to find as well. Can I mix my own with 2 cycle oil and E15? What ratio? 50 HP Mercury. Grandson wants to go fishing.
 
The general consensus is that ethanol blends are bad for boats. I think a lot of that stems from back in the day when fuel systems and tanks weren't designed for ethanol, and some of it is misplaced blame from problems resulting from poor maintenance. I'd try to find REC-90 if you can; in my area there are a half dozen stations within fifteen miles that carry it. Most marinas do as well.

Mixing is no problem. The ratio has been 50:1 just about forever; get the one pint cans if you can and use one pint in your six gallon fuel tank. You want TCW3 oil for your outboard (don't use it in your outdoor power equipment).

I would take a close look at all the fuel system components and see if they need to be replaced before taking the boat on the water. Also, make sure water comes out the little hole in the back; if it doesn't you may need to replace the water pump impeller.
 
The ratio should be molded into the gas cap.

Curious you can't find any premix. You don't have any Tractor Supply stores, Lowes, Home Depots, lawn and garden equipment dealers, chainsaw dealers, etc. in your area?

Of course you can mix your own. Plenty of resources on google to tell you how much oil to add to a gallon of gas for various ratios.

32:1 is 4oz of oil per gallon of gas.

Probably should drain the gas and run the carb dry when you're done if you have to use E15. That way nobody can blame the gas when it won't start next year.
 
I guess I dont understand the problem.
As far as I know here in Manitoba you cant get anything but what is at the pump.
Regular or premium,, thats it.
Every old 2 stroke motor on the lake is running regular gas mixed at 25 or 30 to 1.
At the end of the year we ad stabilizer to the Last tank and run till empty. I dont know why people are so worried about it.
I dont see boats dead on the lake ever so cant be a real problem.
 
> Curious you can't find any premix. You don't have any Tractor Supply stores, Lowes, Home Depots, lawn and garden equipment dealers, chainsaw dealers, etc. in your area?

The premix is intended for outdoor power equipment and uses different oil than outboard oil. Of course, for a fifty year old outboard the type of oil isn't critical. But, more importantly, it's going to get real expensive running twenty+ dollar a gallon premix through a gas-guzzling two-stroke outboard.
 
You can run E15, but it will be hard on the neoprene components. If you can't find straight gasoline, go ahead and run it, but best to drain the carbs when done. Don't just run it out of fuel, but pull the drain plugs, let them drain completely. You might have to remove the silencer cover to get to them, but it is worth it.

Buying premix at the marina is a horrible practice!!! No way they get it right, they use the cheapest bulk oil they can buy, and charge an astronomical price!

The best practice, if you are serious about getting it right, is to have 2 portable 6 gallon tanks. Always start with an empty tank, put in a pint of oil, fill it with 6 gallons of gas (for 50:1 ratio), run it until it is empty, switch to the full tank. That way the ratio stays correct, the gas stays fresh.

An onboard tank is real pain to keep the ratio correct, and they collect water and stale gas. If it has an onboard tank, be a good idea to take it out, clean it, start over with measured gas and oil. If there is room, consider going with the 2 portable tanks instead.

As for oil, always, always, always use either factory Mercury, or factory OMC oil, never use the bargain stuff. It is just nasty! Fouls plugs, smokes, carbons up the piston skirts, just don't!
 
We had a fleet of 20 merc outboard where I worked. For many years e10 was what we had to use because the purchasing dept. contracted with the lowest bid for gas. The older 2 stroke engines ran fine. The newer 4 strokes would get so they wouldn't idle. White corrosion in the tiny low speed fuel passages in the carbs choked off the fuel. I think the 2 stroke oil protected the carbs of the older engines.
 
FWIW, there are two reasons marinas no longer sell pre-mix: Most two-stroke outboards have been fuel-injected since the eighties. And most new outboards are four-stroke these days. I can't remember actually seeing a pre-mix pump, though I think they were common back in the seventies.
 
If sealed, two-stroke oil usually good for up to 5 years. If opened, the shelf life is reduced to 2 years. Once mixed with gas the fuel should be used within two months.

Before ethanol I had a 75 evinrude on a ski boat. I had to use high test gas to make enough horsepower to pull a skier.

My sister has an old outboard. She buys 91 octane for her outboard to get the engine to run right. She lives in Florida. Her boat is kept over the water on a boat lift. In the morning everything is covered with dew..

It's your money. Only mix enough fuel to use ASAP.

Blend your old gas with new gas and use it in a tractor..

People in Florida recommend not using ethanol in boats.
 
I'm no marine engine expert, maybe there are a few professional marine mechanics here to advise you ?? If so listen to the experts NOT me...

That being said FWIW it's my layman's experience having owned several outboards


YES you can mix your own THATS THE ONLY METHOD I DID FOR YEARS and never had a problem

NO I would NOT use Ethanol

Depending on what brand of outboard and their recommendations, I typically ran 30 to 1 maybe 50 to 1
mixture

I preferred Mercury Quicksilver 2 Cycle Oil, never had a problem

Do your homework, consult manufacturers specs, talk to an expert then make an informed decision..The above is ONLY my personal experience and opinion

Best wishes have a good time out there

John T
 
Did it get demolished??


cvphoto126419.png


Todays price for pure 88 octane is $4.55/gl
 
With any two cycle engine run the mix ratio recommended in the owners manual. In my Husqvarna saw I run Husqvarna oil, costs a bit more but runs good. I have been using REC gas with pretty good results. If I were you I would use the gas you can get with a Mercury oil mixed per the Mercury recommendation and go fishing. I suspect you have a removeable tank and an older tractor so, always use fresh fuel in the outboard and burn the old mix in your tractor. My Farm-All H runs perfect on mixed gas. My 4020 gas uses so much gas that a few gallons of mix isn't even noticed.
 
(quoted from post at 06:14:22 05/24/22) Did it get demolished??

Todays price for pure 88 octane is $4.55/gl

The way the post was worded, the name of the station was "Pure-Gas."

Can't quite read it in your picture but it looks like the name of the station is "The Bagel?"

This post was edited by BarnyardEngineering on 05/24/2022 at 07:32 am.
 
50 HP Mercury, is that the four cylinder engine? I had a four cylinder Mercury and it would idle and run very smoothly. I liked that engine. Owners manuals and service manuals are still easy to find in print and especially in PDF form.

On a carburetor engine, I would stick to premium non-ethanol gas. Ethanol blended fuels need richer fuel to air mixture to be burn efficiently and you don't want to run 2 cycle engines too lean. If you are comfortable adjusting the carburetor or pay a mechanic to adjust it, that might work. Myself, I would stick with premium non-ethanol gas in an carbureted outboad.
 
Sitting on the shelf in local wallyworld sporting goods depts. are quarts of Pennzoil Super Premium with semi-synthetic clearly displayed on the container along with the TC-W3 rating for half the price of the Mercury/Quicksilver sitting next to it which tells you nothing about the composition, just has the rating. TC-W3 is rated for Two Cycle-Watercraft, third iteration. I have been using it since I first saw it on the shelf and I have very few problems with my TC engines, fuel related or otherwise. I run the internal engine oiler which runs a variable mix % vs RPM and seldom do I see any smoke on the hole shot...after the first shot coming out of the no-wake zone after sitting up and not being used where it's visible somewhat.

On today's oil vs what I ran early in my boating career.....regular 30w motor oil....auto-truck-utility use and specified at 25:1 (a quart to that 6 gallon can), I would run 50:1 in any TC-W engine.

My latest boat is a 2002 model with a 115 Merc. and it has had premium gasoline it's entire life. In checking fuel line composition in the black engine hoses, a swab run through the inside produces zero little black specks of fuel line degradation as compared to my previous boat of the same year running a 90 hp Merc on E10. I like 91 gasoline as I get much better performance and quicker starts than regular gasoline and since my boat sits up for months at a time between outings, that is worth the price difference.
 
no if it is very old.
on my 40 year old motor one time i put e 10 in it.
from that time on the needle in the carb would stick and i would half to add ait presure to open it up. it was ok for the rest of the day.
 
Mark.

Most outboards built today are 4 stroke.
True.

Most two strokes built today you dont mix oil in the gas. There is a separate tank under the motor cover you fill with oil. The motor does the mixing of the oil with the gas on its own.

I have never heard of using a pre mix in a outboard.
They use to much gas to justify the added cost.
And I have never seen a pump that sells mixed gas in my 60 years.
 
> Most two-stroke outboards have been fuel-injected since the eighties.

Most two-stroke outboards have been OIL-injected since the eighties.
 
(quoted from post at 11:28:58 05/24/22)
(quoted from post at 06:14:22 05/24/22) Did it get demolished??

Todays price for pure 88 octane is $4.55/gl

The way the post was worded, the name of the station was "Pure-Gas."

Can't quite read it in your picture but it looks like the name of the station is "The Bagel?"

Yes, the station in Edmore per the Pure-Gas website list for zero ethanol gas is at 1104 E Main St.
The actual name of the station is The Depot.

I was already familiar with the website and thus new it was not likely a 'Pure Gas'
brand station.

This post was edited by DoubleO7 on 05/24/2022 at 11:20 am.
 
Thanks for the clarification. The search I did this morning called it a 'Pure Gas' station. The depot sells ethanol free for
$5.70 as of 4pm 5-24-22. Maybe it is too far away?
 
(quoted from post at 17:09:36 05/24/22) Thanks for the clarification. The search I did this morning called it a 'Pure Gas' station. The depot sells ethanol free for
$5.70 as of 4pm 5-24-22. Maybe it is too far away?

Blackhole49,
You looking at pure-gas.org ??
or some other?


mvphoto92462.png
 
Mark, where did you get that erroneous idea? My 90 and 115 hp Mercs, both 2002 are carbed and that design lasted till the 2005 year model!
 
Check out this product:
https://vpracingfuels.com/product/4-cycle-small-engine-fuel/?c=352&
It comes in 5 gallon cans also. NO ETHANOL!!
Experts say oil for 2-cycle use will not properly mix with cheap gas with too much ethanol and thus will cause problems with older engines.
 
No... will cause many more problems than you need.. Funny that today.. the coast guard just announced a warning.. to NOT use e15 in marine applications.
 
Ray I use e15 blended in my chain saw all the time, but I would not use it in that motor. It is too old. It would not have the correct gas lines or carb components made to use with E10 or E15.
 
Many many years ago when ethanol first began getting mixed in gasoline there was a big problem with some boats that had on board fiberglass fuel tanks. The alcohol would break down the resin in the 'glass and the fuel tanks would begin to leak. I believe this is the reason the Coast Guard issued warnings about using ethanol/gas mixtures in water craft.
I never owned an oil-injected outboard, always mixed my own. I used the mfg's oil while the motor was in warranty, then switched to off brand products. Never had any motor or carb problems. Sold my last boat and used the money to buy new cylinder heads for the drag race car that ran 100% methanol in the tank. :D
BillL
 
> Mark, where did you get that erroneous idea? My 90 and 115 hp Mercs, both 2002 are carbed and that design lasted till the 2005 year model!

Mark, the post you replied to was a correction to my earlier post. I originally said 'fuel-injected' when I meant to say '[i:654c4848f0]oil[/i:654c4848f0]-injected'. Meaning no need to mix gas and oil.
 
> Many many years ago when ethanol first began getting mixed in gasoline there was a big problem with some boats that had on board fiberglass fuel tanks.

Correct. That's probably the biggest thing that gave gasohol a bad rep in the marine world. These days, manufacturers mostly use aluminum tanks for that reason. But if a customer brings their boat for any fuel-related issue, marina owners automatically blame 'bad gas'. Which, of course, is gas sold anywhere but at their marina.
 
Now that is true. Both of mine are oil injected with the ratio varying from 80:1 at idle to 50:1 somewhere in the power band.
 
(quoted from post at 07:12:21 05/24/22) Inherited a '70s vintage outboard runabout from my son when he passed in October. Actually I advanced him the money and he never paid me back so I guess its mine now. Anyway I can't find premix gas, and recreational is hard to find as well. Can I mix my own with 2 cycle oil and E15? What ratio? 50 HP Mercury. Grandson wants to go fishing.

No no no .
The engine lacks roller bearings so keep the oil gas mix no more than 30:1 .
Use 91 octane unleaded .
 
> The engine lacks roller bearings so keep the oil gas mix no more than 30:1 . Use 91 octane unleaded .

Evinrude went to a 50:1 mix in the mid-sixties.
 

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