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GT40 PRO BOSS efi motor oil?

LOTWLOTW Posts: 157 Baller
Time to put my '95 Nautique away for the winter, what are you guys recommending for engine oil?


  • WIRiverRatWIRiverRat Posts: 65 Baller
    I use Valvoline VR-1 racing oil. Straight 40 weight I believe. High zinc content is what the engine wants and this is the only oil I can find for that.
  • BrennanKMNBrennanKMN Posts: 517 Crazy Baller
    I ran Valvoline VR1 racing oil in my GT-40. It has a higher content of ZDDP for the flat tappet cam in that engine.
  • BraceMakerBraceMaker Posts: 4,149 Mega Baller
    When was the last oil thread on BOS?

    Kendall GT-1 is stocked at my local NAPA and is my preference
  • Jody_SealJody_Seal Posts: 2,901 Mega Baller
    Gt-40 straight 40 was originally recommended. 15W-40 is current from PCM. Also a ZDDP additive is recomended for that engine platform.
    Hobby Boats can be expensive when the hobbyist is limited on their own skill and expertise.

  • CentCent Posts: 177 Baller
    I useVR1 in my Classic wooden mahogany 1966 Century Resorter 17.5 foot Ski Boat. Complete with Pylon and built in rear boarding ladder. Engine is a 1966 AMC Graymarine 238 HP Fireball 337 V8. Engine runs strong purrs like a kitten.
  • CBR51CBR51 Posts: 99 Baller
    I have always used Mobil One 15w-50. You can get it at Walmart
  • Orlando76Orlando76 Posts: 1,208 ★★★Triple Panda Award Recipient ★★★
    Valvoline VR1 only for the flat tappet. 10w40 or 20w50.
  • CBR51CBR51 Posts: 99 Baller
    Mobil one 15-50 good for flat tappet too. ZDDP levels 1200. I agree Valvoline VR1 maybe better ZDDP 1300. I just have a easier time finding the Mobil One
  • Ronny61Ronny61 Posts: 17 Baller
    Another good choice

    Royal Purple HPS 20W-50 Synthetic Motor Oil

    Royal Purple HPS Series motor oil is specifically formulated to maximize performance and meet the demands of high performance and modified engines. HPS is high performance street motor oil recommended for vehicles no longer under manufacturer warranty and for those seeking a higher level of performance and protection.

    Royal Purple’s HPS is fortified with a high level of zinc/phosphorus anti-wear additive and Royal Purple’s proprietary Synerlec additive technology. This unique blend enables HPS to outperform leading high performance synthetic oils and conventional lubricants for both gasoline and diesel engines.

    Royal Purple HPS Series of motor oil responds to increased pressure with increased viscosity. Improved sealing between the piston ring and cylinder wall maximizes horsepower and torque. Its advanced additive technologies improve the condition of metal-to-metal contact under severe load. The advantages are clear. Take a look at the following photos:
    HPS Advantages

    Exceptionally high film strength dramatically reduces engine wear and engine heat to extend the life of your engine. Improved sealing between the piston ring and cylinder wall maximizes horsepower and torque and optimizes fuel economy. Exceptional oxidation stability extends oil life and allows for more miles driven between oil changes saving you time and money and reducing the impact on the environment. Advanced synthetic solvency reduces engine deposits and keeps engines clean for increased fuel economy and engine longevity.

    HPS protects valve trains using roller or flat tappet lifters that require added protection due to high lift/ high ramp rate camshafts. It also provides maximum protection, extends engine life and ramps up efficiency. For vehicles under warranty, Royal Purple recommends its API-licensed oils available at retailers nationwide.
  • herseyjherseyj Posts: 24 Baller
    Valvoline Racing VR1 40W. Some Napas and OReilly's stock it. My local Napa never takes more than a day to get a case in if they are out.
  • CentCent Posts: 177 Baller
    My NAPA normally has Valvoline VR 1
  • LOTWLOTW Posts: 157 Baller
    Thanks for all the input, very difficult to find these in small town Canada but was able to order the Mobil One through NAPA today. No one could get me the Valvoline VR1.
  • MDB1056MDB1056 Posts: 361 Solid Baller
    Lucas also makes an exceptional ZDDP additive
  • WindsurfnutWindsurfnut Posts: 121 Baller
    @lotw Rotella T4 15w40 is readily available in Canada, often on sale, and has high ZDDP levels. Lots of discussion out on the net - but Shell does confirm on a Bobstheoilguy thread the ZDDP content.
  • WishWish Posts: 7,983 ★★★Triple Panda Award Recipient ★★★
    edited September 2019
    What is "flat tappet" for the non gear heads? Flat tappet verses what other kind of valve trains are used in ski boats?
    >>> 11.25..a different kettle of fish. <<<
  • WindsurfnutWindsurfnut Posts: 121 Baller
    edited September 2019
    Roller lifter
  • BraceMakerBraceMaker Posts: 4,149 Mega Baller
    edited September 2019
    Roller rocker since... Early 90s?
  • GloersenGloersen Posts: 984 Crazy Baller
    @Wish - "you can never have enough horsepower..."
  • WishWish Posts: 7,983 ★★★Triple Panda Award Recipient ★★★
    @Gloersen PERFECT 👍 Thanks
    >>> 11.25..a different kettle of fish. <<<
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