I bought a boat with a 1994 evenrude 40hp outboard. I know that the guy put in the guy used evenrude oil?

I dont however know if what he used was conventional or synthetic. I bought synthetic but have not put it in yet. Will it hurt anything if I put in the synthetic, and he has conventional in it?

Update:

SOLVED: I realized that the Evenrude Johnson oil has a different color for the conventional and synthetic. I checked, and found that the boat has conventional oil on it now, so i guess it's back to the store to get a new jug of oil. Thank you

3 Answers

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  • 1 month ago

    Why did he put used engine oil in himself?

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  • Barry
    Lv 5
    1 month ago

    Often motor manufacturers recommend straight oil because they always have and the engines wear out quicker. That keeps their sales going. Fully synthetic oil is superior to straight oil and will benefit your motor. The myths about it being thinner causing problems is utter rubbish. My thirty year old lawn mower has had 5w-40 fully synthetic from day one and starts first time every time. So use the oil you have if you want your motor to last.

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  • 1 month ago

    If you know conventional is what was being put in it that is what you should stick with.

    From what I've been instructed is that the molecular structure of synthetic oil is smaller than conventional. Which can cause oil leaks if you switch from conventional to synthetic. If you know what's been put in it just stick with that. 

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    • John1 month agoReport

      I've never heard anyone say that before. I have always heard to not mix or switch when changing oil. It's a risk I wouldn't take myself. I'd rather change oil regularly than potentially create more work by needing to replace seals due to switching oils. But if it's worked for you, that's awesome.

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