Mariner 40 year 2000 pre mix

[Keith 1]

Hello.
Can anyone help me with the pre mix on the above please.
Also the best oil that can be used.
Also I have seen the engine internal cleaner seafoam !
Has anyone used this or is it not really productive.
Thanks

[spartacus]

If not Autolube, then 50:1 and you can’t go wrong. May smoke a bit like an old navy destroyer, but better than seizing. Yamahas used to have 100:1 stickers.

For oil, anything that’s specified to TC-W3. Quicksilver is my oil of choice.

[Nos4r2]

Exactly what Spartacus said.

[paintman]

Recommendation for the oil injection Mercury V6 2-strokes when the oil injection system is removed is premix 50:1.
Factory manual gives 50:1 for those V-135hp through V-225hp engines not fitted with oil injection

Quicksilver TC-W3 for me too.

My Suzuki DT4 recommends 100:1 but in the owner's manual it says for commercial use & South Africa use 50:1.
I'm not in SA & don't use it commercially but it too gets 50:1.
Perhaps a bit more smoke but I've not had any problems.

[Keith 1]

That seems the way to go then.
I will use that ratio.
Thankyou.
So do you think once it's mixed it has a kinda shelf life ! Where the fuel performance drops off.

[Matt]

I'd agree with 50:1 all the way. 100:1 is just hardly anything at all.

[paintman]

Originally Posted by Keith 1

That seems the way to go then.
I will use that ratio.
Thankyou.
So do you think once it's mixed it has a kinda shelf life ! Where the fuel performance drops off.

That's a whole new can of worms & gets regular openings on here & car forums!
In an unsealed container fuel will deteriorate quicker than in a full & sealed container.
As my tanks are the plastic type & the biggest ones only hold 25 litres it doesn't last long enough for me to be concerned.
That said, I wouldn't be unduly bothered if the fuel is a few months old but I do close the tank vents at the end of each day's usage.
I think it's going to be more of an issue for those with large inbuilt fuel tanks.

At the end of the season I drain all remaining fuel - normal petrol for the main engine as it's an oil injection 2-stroke & the fuel tanks just hold petrol - and the small quantity of 50:1 premix from the Suzuki & it all goes into my car.
The car's pushing 40 years old so none of the modern electrickery stuff & I've had no issues, but it's only a tiny amount of 2-stroke oil anyway which would be massively diluted.

[spartacus]

Originally Posted by Keith 1

So do you think once it's mixed it has a kinda shelf life ! Where the fuel performance drops off.

You live in Scotland, so unless you’re considering boating after October, it will be unused until early April, so basically 6 months.

You’ve nothing to worry about. Seal up the vent screw.Yyou can top up with fresh fuel and add another glug of oil.

I use some of the petrol in 4-stroke lawnmower, 2-stroke strimmers and chainsaw.

[Keith 1]

I like the re use.
Thanks again for your help

[Matt]

I certainly have had fuel go off.

But I can also be sure that if I popped out to the garage right now and fired up the Johnson 5hp on it's year old fuel, it'd run just fine and the 10L tank I have for it seals properly.

So you've just got to use a bit of common sense. The sniff test works for me - if it smells more like white spirit than petrol, it's gone off and needs ditching.

The other thing I do is always put 97 or 99 octane in the boat engines. They don't need the octane, but I go for the lower ethanol (5%) fuel so it has less tendency to absorb moisture.

As paintmain says, we could probably fill ribnet with fuel threads covering oils, octane, ethanel etc, but in my experience, just use a bit of judgement and common sense. It's like the "what oil" threads on car forums - lots of posts say "I've had good luck with brand x" when you know any other brand would be just fine.