Mixing or changing 2 stroke oil

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Johny
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Mixing or changing 2 stroke oil

Post by Johny » Apr 13th, '18, 11:06

Hi all.
I have read dire warnings about changing the brand of 2 stroke oil. Things like the mix causing an emulsified mess in your fuel etc.
How diligent do I have to be. Would simply draining the fuel tank, exhausting the carbs of fuel and doing a new mix be enough? Assume I used it immediately.
My first 2 tankfuls were Penrite (synthetic) and I can get Gulf Western more easily (synthetic).

Edit: Changed Penrite to synthetic. Also mixed a little of each oil. Mixed perfectly - same consistency.
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Tezza
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Re: Mixing or changing 2 stroke oil

Post by Tezza » Apr 13th, '18, 14:19

Am guessing both are Marine TT so would not see any issue as a one off.
I’m using Penrite synthetic marine tt since I purchased back in Sept and I have no idea what oil was previously used . Come to think of it the fuel tank was quarter full when I topped up.No issues
From my tt motorcycle days both premix and oil injection never had an issue mixing oils from different manufacturers.
I believe the stories of clogging up hark back to when there was mineral and castor based oils and mixing did cause such issues.
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zebedee
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Re: Mixing or changing 2 stroke oil

Post by zebedee » Apr 13th, '18, 15:32

Johny wrote:I have read dire warnings about changing the brand of 2 stroke oil. Things like the mix causing an emulsified mess in your fuel etc.
How diligent do I have to be.
If in doubt, why not test to see what happens?
Put half a litre of fuel with the current oil in a glass container, add the proposed new brand of oil at the correct ratio. Seal, shake vigorously, let sit for as long as it takes (minutes? hours? a month?) for you to feel comfortable that nothing untoward is going on.
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Gezza
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Re: Mixing or changing 2 stroke oil

Post by Gezza » Apr 13th, '18, 16:20

If you worried just start the engine with no fuel line connected and let it use up what ever is in the Carbie till it stops then connect your tank and run it for a few minutes and all your old fuel should have been used.
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Johny
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Re: Mixing or changing 2 stroke oil

Post by Johny » Apr 13th, '18, 16:35

Thanks every one. I'll do both - mix up a test batch and do the run dry and new fuel thing.
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Re: Mixing or changing 2 stroke oil

Post by Bligh » Apr 13th, '18, 16:45

I know oil in a sump with its additives can cause problems down the track when changed as some additives interact with others, a friend pointed this out to me when he was teaching mechanics in the Army and they did regular tests with oils.
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Re: Mixing or changing 2 stroke oil

Post by INMA » Apr 13th, '18, 20:37

Most two stroke outboard fuel/oil mixing problems are due to using old fuel and not measuring the oil being added properly. Using cheap oils is another cause of problems.

I always use the correct NGK spark plug and close the gap 20% to reduce the stress on old ignition systems.

You don't mention what brand two stroke engine you are using but be aware different brands and models use different oil ratios.

To complicate things further, some TSPers use JASO FC oils instead of the outboard oils. From memory, those using the superior JASO FC use less oil in the mix taking advantage of the superior oil to reduce smoke.

I've used a single oil for motorbikes, tools and outboards for decades, but I am very careful measuring the fuel oil ratio.

On startup while tied to the jetty, I put the outboard in gear and give it a hot test run while I sort my gear. If it runs fine at the jetty, its should be good underway.
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Gezza
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Re: Mixing or changing 2 stroke oil

Post by Gezza » Apr 13th, '18, 20:51

All true, but I think we all including me worry a bit too much about our outboards, go to Indonesia or the Phillipines the fisherman there run their engines full thrusts ( which is actually better I think) for hours on end and they seem to keep running. I don’t think they will spent money on premium oil or the servicing schedule.
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Johny
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Re: Mixing or changing 2 stroke oil

Post by Johny » Apr 14th, '18, 11:06

INMA wrote: You don't mention what brand two stroke engine you are using but be aware different brands and models use different oil ratios.
It's a Tohatsu 9.8HP 2 stroke. I'm still running in (1st 10 hours) so am mixing 25:1 (pretty accurately).

So far the Penrite and Gulf Western cocktail looks good (experiment).
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Re: Mixing or changing 2 stroke oil

Post by pdandy » Apr 14th, '18, 11:27

Johny wrote:
INMA wrote: You don't mention what brand two stroke engine you are using but be aware different brands and models use different oil ratios.
It's a Tohatsu 9.8HP 2 stroke. I'm still running in (1st 10 hours) so am mixing 25:1 (pretty accurately).

So far the Penrite and Gulf Western cocktail looks good (experiment).
Relax, I'll be impressed if you manage to hurt a toey 9.8! I tried all types of evil things to mine before accepting I should just buy a 4 stroke and park the toey. I'd be willing to bet that after 4/5 years in the shed that toey would still fire up and run flawlessly. Mine used to run on whatever motorbike oil was left in the shed - so all synthetic but several different brands.
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Tezza
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Re: Mixing or changing 2 stroke oil

Post by Tezza » Apr 14th, '18, 13:10

Just a thought , what does your warranty booklet say about approved oils .
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Gezza
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Re: Mixing or changing 2 stroke oil

Post by Gezza » Apr 14th, '18, 18:48

I am in the same boat, just bought the tohatsu 9.8B ultra long, it is not really specific to what brand, just TCW3 oil and yes 25:1. Don’t worry it be fine, as pdandy said they are tough little things. Do the breaking in thingy and you done your bit. I will use it as a guide but for sure will run out of patience and I am also sure she will survive.
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Johny
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Re: Mixing or changing 2 stroke oil

Post by Johny » Apr 17th, '18, 11:16

Tezza wrote:Just a thought , what does your warranty booklet say about approved oils .
They just say TCW3 but that's where the dire warnings came from.

The Tohatsu manual warns "The mixing of different brands, or different kinds even if the same brand, may cause gelling, resulting in blockage if filter screens. This may lead to serious engine damage due toothed lack of lubrication.".

It kind of sounds like that would be unusual from the feedback I've received here.
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