MacGregorSailors.com

Gas additives for 4 stroke OB's

Hi dlandersson, Are you recommending that product in the video you posted (Gummout Multisystem Tuneup) for outboards on macs? Or are you using that product, or starting a discussion on additives, with and without corrosion resistant chemicals for 4-cycle outboards? I searched the archives for "additives", and found quite a few posts, but not much on the tradeoffs of different brands of additives for modern outboards with fuel injection. I would like to learn more about this subject, because outboards in southeast Alaska seem to have a lot of fuel problems, even though Alaska was exempt from the ethenol requirements the last time I checked.

I'm just posting the video for the information. Full disclosure: I had been using "Seafoam" because an old sailors recommended it. Scotty (with 4 million views) explains that Seafoam was developed for 2-stroke engines and suggests Gum Out. Sheep that I am, I went out and got some "Gum Out Multi-engine" - it was harder to find than I expected.

JeffJuneau wrote: ↑Sun Oct 03, 2021 3:33 pm Hi dlandersson, Are you recommending that product in the video you posted (Gummout Multisystem Tuneup) for outboards on macs? Or are you using that product, or starting a discussion on additives, with and without corrosion resistant chemicals for 4-cycle outboards? I searched the archives for "additives", and found quite a few posts, but not much on the tradeoffs of different brands of additives for modern outboards with fuel injection. I would like to learn more about this subject, because outboards in southeast Alaska seem to have a lot of fuel problems, even though Alaska was exempt from the ethenol requirements the last time I checked.

Well dlandersson then I guess I should also disclose that I have been using the Evinrude 2+4 fuel conditioner stabilizer that also has a corrosion inhibitor, and I noticed that the stabilizer that honda produces says that it includes a corrosion inhibitor. The Evinrude dealer for my previously owned e-tec outboard (I have a Suzuki in my 26M) told me I should use 2+4 in every tank of gas because Alaska in general has a "the biggest problem of any state in the US with water- contaminated gas". I have no idea if 2+4 it is any better than seafoam or stabil.

Seafoam is mostly ethanol/alcohol.
If you add it.. and run it all out.. no big deal
If you add it.. and DO NOT burn out your tank.. it will make a mess.
(see my carb photos.. I also posted whmis/msds sheets)

Not worth it... just get 0 % ethanol gas...
If your OB is running poorly.. do the right thing (no quick fix) clean the carbs... or the fuel injectors.. (machines run from 100-sky is the limit)
If your carb'ed make sure they are synced as per the service manual.. makes a big difference.. MUCH better Fuel Burn... runs much better.

AD

Seems there is a love/hate relationship with Seafoam.
Fresh gas and use it up and all good.
Leave sit too long and unhappiness.

They now also make a version without ethanol good for 2-strokes and also apparently for 4-stokes.
At least it seems to be advertised as such.

While regular Seafoam does have other stuff that seems to help old 2-strokes run better.
Guess the thing to do is only get enough fuel to use up?
If anyone can do that trick regularly and not be left a drift on a regular basis please, please share you methodology
More than willing to learn a new trick

Best Regards
Over Easy

In a previous post I put up the MSDS sheet.
All Seafoam is .. is alcohol.

So when you buy marine gas... without alcohol.. you just ruined your gas
It works so .so..
If and only if.. you run the tank out VERY QUICKLY so no water is absorbed.
If you use it ever day.. look at my posts of my carb and all the debris that were in it from seafoam.
(posted last year .. it was crazy with precipitate.)

BEST thing to use (and this is from working in the big 3 with Dyno Lab tests)
is gas with NO alcohol.. nothing more. (Top Shelf fuel does have detergents for direct inject engines.. which in our HP range, I do not believe there are any that inject directly, rather than across the valves)

There is no magic cure all gas additive..
If your gumming up the carb/injectors.. clean them.. that would be in the case of a marine engine water in the fuel.. or way worse.. alcohol that absorbed water..

If your saving your gas for along time.. stabilizer is ok.... but if that is the case.. just put it in your car.. and be done with it. WHY store gas for months and risk gumming up the outboard.

They use a Hydrocarbon solvent blend.. and Isopropanol.
The marine pro version (not the one shown in the video.. the BLUE can) .. is better.. not perfect.. it excludes the Isopropanol... but uses a Hydrocarbon solvent blend ONLY (they wont publish what it is.. trade secret)
Remember Isopropanol is a petroleum distillate.. and small amounts are in the "blend"

Seafoam States:

"BE AWARE: No fuel treatment can resolve direct water contamination or fuel phase separation. Any fuel contaminated with water is ruined and should be removed immediately. However, very small amounts of water in fuel can be managed by isopropyl alcohol."


My old post shows what seafoam RED did to my outboard's carbs.

viewtopic.php?p=344897&hilit=carb#p344897

Seafoam is a mixture of Naphtha, Pale oil, and isopropyl alcohol. For me it has worked great as a "spring cleanout" additive for outboards and other small motors. For storage, most people use a non-alcohol additive. I usually use Startron or Stabil. It's worked great for me. Getting non-ethanol gas is extremely hard around where I live.

http://www.fuel-testers.com/is_gas_addi ... _list.html

Mazda recommends adding a container Techron every 5000 miles to reduce engine carbon buildup on pistons and valves. I know it sounds like snake oil, but yes, it actually does work. I now use it in all my 4-cycle engines.I also only use “top tier” fuels in my cars (look for the logo on the pump- Costco and Shell both have it), since “Top Tier” fuels also contain similar additives to Techron to reduce carbon.

NO ALCHOHOL in any of my small motors. It will mix with any water in your tank and can start making a mess of carbs due to the water remaining in them causing corrosion/exfoliation and bad things can happen. It will swell up the rubber hoses and seals. Lots of rubber fuel lines on a boat.

kmclemore wrote: ↑Sat Feb 19, 2022 1:05 pm I also only use “top tier” fuels in my cars (look for the logo on the pump- Costco and Shell both have it), since “Top Tier” fuels also contain similar additives to Techron to reduce carbon.

This is a great tip. I always thought this was some marketing gimmick. After looking it up, I see it's worth seeking out. THANKS!

Carbon up in cars is on the intake valves.
Initially the fuel injector would SPRAY the back of the valves.. but now with new engine designs, they spray directly into the cylinder.
Thus, not spraying the intake valve's back side. .. and they carbon up. (ie: Direct Inject will carbon up )

Chrysler released a TSB for their 3.5L that this may happen, and once a week rev to 5500rpm for 30 sec to knock all the carbon off.
(valves go in and out.. but ALSO spin.)

With an OB, many ppl run them at high revs far more often than a person driving a car.
If the OB is not direct inject.. and one revs it up every now and again.. carbon up should not be that big an issue at all.

Using an non-alcohol based fuel additive is ok.. but often just running good Super Unleaded.(no alcohol) and top shelf fuel (has additives already) its not really needed. Will do no harm.. other than to your wallet...

Techron is ok.. no alcohol.... maybe run it once a season to clean up any fuel injectors.. as more of a precaution.. and piece of mind.

AD