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  1. #1

    Default Oil brand and type

    Have a pair of 1985 Mercruiser 5.0L 305ci motors, what brand and type of oil do you use?

  2. #2
    Join Date
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    Spotswood, NJ, USA
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    Default Re: Oil brand and type

    Rotella diesel , 20W-50, 25W-40 Merc oil and a splash of Marvel Mystery Oil in the gas and oil

  3. #3
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    Default Re: Oil brand and type

    Marvel Mystery Oil..... a blast from the past. My Dad's favorite.
    Capt Bob
    1969 23ft ChrisCraft Lancer
    Merc 5.7L 260HP/ Volvo 280

  4. #4
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    Default Re: Oil brand and type

    It does work as intended, trust me.My F250 351 went a bit over 400K.

  5. #5
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    Default Re: Oil brand and type

    I run Mobile One 15-50 Grey cap. 5 qrt jug at Walmart is ~ $25.00
    Napa Gold oil filter.
    Jack
    Mass.

  6. #6
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    Default Re: Oil brand and type

    Straight 30wt in 5 gallon pails. Walmart has it in gallon jugs. Marine engines are more like industrial than transport engines. A heavy-duty lube like the 30wt is recommended by most marine manufacturers.
    Multi vis oils are overkill for marine engines since they typically do not operate in below-freezing conditions.
    Practicing the ancient art of ren-ching

  7. #7

    Default Re: Oil brand and type

    Before I posted this question I was planning to use this.... so it sounds like I should switch..???

    https://www.napaonline.com/en/p/NO_75115

  8. #8
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    Default Re: Oil brand and type

    That will work but seems super expensive
    Practicing the ancient art of ren-ching

  9. #9
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    Default Re: Oil brand and type

    .."Multi vis oils are overkill for marine engines since they typically do not operate in below-freezing conditions"

    That has nothing to do with it! Every time a cold motor starts up the bearings take a beating until the oil pressure comes up. Using a 10W30 (for example) oil lessens that beating.

    Multi vis oils are a modern miracle of lubrication engineering. Why on earth would anyone still use straight weight oil from the 1930s?

    Jeff

  10. #10
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    Default Re: Oil brand and type

    The only reason to use multi vis is to cover wide temperature conditions. The "W" is for "winter", not "weight". Your 10W-30 still behaves just like straight SAE30 in warm weather.
    Last edited by o2batsea; 08-09-2017 at 07:05 PM.
    Practicing the ancient art of ren-ching

  11. #11
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    Default Re: Oil brand and type

    Per a conversation I has with Andy Granatelli ( I bought an engine from him once).... multi weights for hydraulic liftered engines... "straight" for mechanicals...
    Capt Bob
    1969 23ft ChrisCraft Lancer
    Merc 5.7L 260HP/ Volvo 280

  12. #12

    Default Re: Oil brand and type

    I had twin 1982 Merc 5.0. Manual called for marine 30w. Multi weight only if no straight weight was available. Upgrade to 5.7's last year. 5.0 were still kicking. I use Pennzoil and sometimes West Marine brand when on sale for $20.
    .

  13. #13
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    Default Re: Oil brand and type

    .."The only reason to use multi vis is to cover wide temperature conditions. "

    I believe I already covered that inaccuracy. Every time a motor fires up--with still no oil pressure--it needs a thinner oil to get things going.

    Jeff

  14. #14
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    Default Re: Oil brand and type

    Ugh. Flat earthers.
    Practicing the ancient art of ren-ching

  15. #15
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    Default Re: Oil brand and type

    All I will say is use what ever you want as long as it meets Manufactures specifications.

    If in doubt, use their oil only and you wont have to ask this type of question.

    Mercs spec for almost all engines is 25w-40w standard non synthetic oil and a "tiny" oil filter.



    Yet they use synthetic gear oil now............go figure.
    Jack
    Mass.

  16. #16
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    Default Re: Oil brand and type

    ^This^
    Practicing the ancient art of ren-ching

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