About this item

• Product Overview

  Delivers exceptional wear protection, even when contaminated with up to 15 percent water.¹ Extreme-pressure formulation controls damage from shock-loading caused by propeller cavitation. Excellent for fast-accelerating, high-horsepower boats. Protects against rust and corrosion. Keeps seals soft to minimize water leakage. Compatible with other synthetic and conventional oils. Use in fresh- and saltwater applications that require 75W-90 or 80W-90 gear lube and any of the specifications listed below, including lower units made by Mercury/ Mariner,* Johnson/Evinrude,* Bombardier,* Honda,* Yamaha,* Suzuki,* Force/US Marine,* Nissan,* Tohatsu* and Harbormaster;* sterndrives made by Mercruiser-Bravo,* OMC/Bombardier, Volvo-Penta,* Yanmar,* Konrad* and Marine Drive Systems;* V-drives made by Casale & Menkins;* bow thrusters made by Harbormaster Marine;* and transmissions made by ZF Marine Transmission.*

  • API GL-4, GL-5

  See the product data sheet for full details.

  ---

  PROTECTS AGAINST WEAR

  • Fortified with extreme-pressure (EP) additives for superior protection of fast-accelerating, high-torque/horsepower engines.
  • Protects against shock loading from cavitation of heavily loaded engines.
  • Delivers advanced outboard protection against power loss and gear wear, even with up to 15 percent water contamination.¹

  ---

  RESISTS RUST & FOAM

  • Designed to prevent rust and is compatible with aluminum, copper and brass alloys.
  • Resists foam despite water contamination to ensure a strong fluid film and excellent wear protection.
  • Promotes long seal life to help prevent water intrusion.

  ---

  EASY-PACK EASES MAINTENANCE

  • Award-winning AMSOIL easy-pack reduces mess and hassle when changing lower-unit gear oil.
  • Eliminates the need to buy and store a messy gear-lube pump.

  See the product data sheet for full details.

  ¹ Based upon AMSOIL testing of AMSOIL 75W-90 Synthetic Marine Gear Lube in ASTM 3233 and ASTM D892.

  *All trademarked names and images are the property of their respective owners and may be registered marks in some countries. No affiliation or endorsement claim, express or implied, is made by their use.

• Technical Specifications
  Data Bulletin

  Data Bulletins

  Warranty

  WARRANTY

  SDS

  SDS

  
  
  
• Product Reviews
  4.9 star rating

  Based on 107 reviews

  Based on 107 reviews

  See all customer reviews

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  Most Recent Most Helpful Highest Rating Lowest Rating Oldest

  • 5 star rating
    Johnson 150 faststrike
    By  SAM,  a  Verified Buyer  from  Ohio  on  January 18, 2026

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    If you want to keep your lower unit intact you have to either run a quality oil or change it very frequently. This gear oil gives me confidence in knowing I will be protected until my next oil change vs changing lower unit oil 4x per year with the cheap stuff.
    Bottom Line

    Yes, I would recommend this to a friend.
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  • 5 star rating
    Superior lubrication and water intrusion protection.
    By  K LAMAR,  a  Verified Buyer  from  Chattanooga   on  November 25, 2025

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    Don’t go boating without it.
    Bottom Line

    Yes, I would recommend this to a friend.
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  • 5 star rating
    Outboard
    By  DENNY,  a  Verified Buyer  from  Indiana   on  October 29, 2025

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    I have a 2019 Suzuki 90hp and a 1994 Mercury 115hp and use Amsoil gear lube in each one. Thanks
    Bottom Line

    Yes, I would recommend this to a friend.
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  • 5 star rating
    Marine Gear Lube
    By  DARIN,  a  Verified Buyer  on  October 23, 2025

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    I absolutely love this stuff! Why would you ever want to put "good enough" products in your investments when you can use "the BEST" for often times cheaper. Worry free with this stuff and ALL Amsoil products!
    Bottom Line

    Yes, I would recommend this to a friend.
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  • 5 star rating
    Mercury Marine gear lube
    By  DAVID,  a  Verified Buyer  from  Hudson Wisconsin  on  October 19, 2025

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    I switched to amsoil Marine gear lube full synthetic had been using Quicksilver or Mercury Marine 75/90 w in the past but the reviews for amsoil full synthetic surpassed all recommendations so I changed it this fall and we'll see how things go in the spring 2026
    Bottom Line

    Yes, I would recommend this to a friend.
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  • 5 star rating
    good stuff
    By  STEVEN,  a  Verified Buyer  from  quebec  on  September 09, 2025

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    im a certified marine tech and i use that oil in all lower units, volvo, mercruiser, mercury, johnson, evinrude, honda, ect
    Bottom Line

    Yes, I would recommend this to a friend.
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  • 5 star rating
    Marine gear lube
    By  DAVE,  a  Verified Buyer  on  August 26, 2025

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    Put this in an older outboard I recently got, shifting is quiet and smooth
    Bottom Line

    Yes, I would recommend this to a friend.
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  • 5 star rating
    How does one review a gear lube?
    By  ALAN,  a  Verified Buyer  from  Alberta  on  August 22, 2025

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    I don’t know how to review a marine gear lube. I am hoping the good people at Amsoil make a good product, but honestly, I have no way of knowing for sure. However, the packaging is the best compared to other bottles of gear lube I have used. It made filling the gear box much easier and for this I gave 5 stars.
    Bottom Line

    Yes, I would recommend this to a friend.
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  • 5 star rating
    Amsoil marine gear lube
    By  JEFF,  a  Verified Buyer  from  Myrtle Beach, SC  on  August 01, 2025

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    At first appearance this product may be mistaken as just normal gear lube. WRONG, it takes a chemical to remove from your hands so just imagine how well it is protecting the internals of your lower unit! Will use as long as I have a boat! Amsoil rocks!
    Bottom Line

    Yes, I would recommend this to a friend.
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  • 5 star rating
    Glad to get it in my new Merc 90
    By  RANDY,  a  Verified Buyer  from  Hartland Mich  on  July 30, 2025

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    Brand new 2025 Mercury 90. Peace of mind now that break in is complete and Amsoil is in. c”,)
    Bottom Line

    Yes, I would recommend this to a friend.
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• Highlights

  • Excellent gear and bearing protection, even when contaminated with 15% water¹
  • Reduced friction and wear
  • Protection against rust and corrosion
  • Long seal life
  • Superior foam prevention

    ¹Based upon AMSOIL testing of AMSOIL 75W-90 Synthetic Marine Gear Lube in ASTM 3233 and ASTM D892.

• Returns

  We offer easy returns for customers. If your product is unused and unopened, you may return it within 30 days for a full refund of the purchase price. View full AMSOIL Return Policy.

• Payments

  We accept Visa, Mastercard, American Express, Discover and PayPal, and provide secure checkout and encrypted payment processing.

• Product Overview

  Delivers exceptional wear protection, even when contaminated with up to 15 percent water.¹ Extreme-pressure formulation controls damage from shock-loading caused by propeller cavitation. Excellent for fast-accelerating, high-horsepower boats. Protects against rust and corrosion. Keeps seals soft to minimize water leakage. Compatible with other synthetic and conventional oils. Use in fresh- and saltwater applications that require 75W-90 or 80W-90 gear lube and any of the specifications listed below, including lower units made by Mercury/ Mariner,* Johnson/Evinrude,* Bombardier,* Honda,* Yamaha,* Suzuki,* Force/US Marine,* Nissan,* Tohatsu* and Harbormaster;* sterndrives made by Mercruiser-Bravo,* OMC/Bombardier, Volvo-Penta,* Yanmar,* Konrad* and Marine Drive Systems;* V-drives made by Casale & Menkins;* bow thrusters made by Harbormaster Marine;* and transmissions made by ZF Marine Transmission.*

  • API GL-4, GL-5

  See the product data sheet for full details.

  ---

  PROTECTS AGAINST WEAR

  • Fortified with extreme-pressure (EP) additives for superior protection of fast-accelerating, high-torque/horsepower engines.
  • Protects against shock loading from cavitation of heavily loaded engines.
  • Delivers advanced outboard protection against power loss and gear wear, even with up to 15 percent water contamination.¹

  ---

  RESISTS RUST & FOAM

  • Designed to prevent rust and is compatible with aluminum, copper and brass alloys.
  • Resists foam despite water contamination to ensure a strong fluid film and excellent wear protection.
  • Promotes long seal life to help prevent water intrusion.

  ---

  EASY-PACK EASES MAINTENANCE

  • Award-winning AMSOIL easy-pack reduces mess and hassle when changing lower-unit gear oil.
  • Eliminates the need to buy and store a messy gear-lube pump.

  See the product data sheet for full details.

  ¹ Based upon AMSOIL testing of AMSOIL 75W-90 Synthetic Marine Gear Lube in ASTM 3233 and ASTM D892.

  *All trademarked names and images are the property of their respective owners and may be registered marks in some countries. No affiliation or endorsement claim, express or implied, is made by their use.

• Technical Specifications
  Data Bulletin

  Data Bulletins

  Warranty

  WARRANTY

  SDS

  SDS

  
  
  
• Product Reviews
  4.9 star rating

  Based on 107 reviews

  Based on 107 reviews

  See all customer reviews

  Sort by

  Most Recent Most Helpful Highest Rating Lowest Rating Oldest

  • 5 star rating
    Johnson 150 faststrike
    By  SAM,  a  Verified Buyer  from  Ohio  on  January 18, 2026

    Open report issue form

    Describe the issue

    Failed to verify captcha

    Cancel Submit
    If you want to keep your lower unit intact you have to either run a quality oil or change it very frequently. This gear oil gives me confidence in knowing I will be protected until my next oil change vs changing lower unit oil 4x per year with the cheap stuff.
    Bottom Line

    Yes, I would recommend this to a friend.
    Was this review helpful?

    YES (0) NO (0)
  • 5 star rating
    Superior lubrication and water intrusion protection.
    By  K LAMAR,  a  Verified Buyer  from  Chattanooga   on  November 25, 2025

    Open report issue form

    Describe the issue

    Failed to verify captcha

    Cancel Submit
    Don’t go boating without it.
    Bottom Line

    Yes, I would recommend this to a friend.
    Was this review helpful?

    YES (0) NO (0)
  • 5 star rating
    Outboard
    By  DENNY,  a  Verified Buyer  from  Indiana   on  October 29, 2025

    Open report issue form

    Describe the issue

    Failed to verify captcha

    Cancel Submit
    I have a 2019 Suzuki 90hp and a 1994 Mercury 115hp and use Amsoil gear lube in each one. Thanks
    Bottom Line

    Yes, I would recommend this to a friend.
    Was this review helpful?

    YES (0) NO (0)
  • 5 star rating
    Marine Gear Lube
    By  DARIN,  a  Verified Buyer  on  October 23, 2025

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    Describe the issue

    Failed to verify captcha

    Cancel Submit
    I absolutely love this stuff! Why would you ever want to put "good enough" products in your investments when you can use "the BEST" for often times cheaper. Worry free with this stuff and ALL Amsoil products!
    Bottom Line

    Yes, I would recommend this to a friend.
    Was this review helpful?

    YES (0) NO (0)
  • 5 star rating
    Mercury Marine gear lube
    By  DAVID,  a  Verified Buyer  from  Hudson Wisconsin  on  October 19, 2025

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    Describe the issue

    Failed to verify captcha

    Cancel Submit
    I switched to amsoil Marine gear lube full synthetic had been using Quicksilver or Mercury Marine 75/90 w in the past but the reviews for amsoil full synthetic surpassed all recommendations so I changed it this fall and we'll see how things go in the spring 2026
    Bottom Line

    Yes, I would recommend this to a friend.
    Was this review helpful?

    YES (0) NO (0)
  • 5 star rating
    good stuff
    By  STEVEN,  a  Verified Buyer  from  quebec  on  September 09, 2025

    Open report issue form

    Describe the issue

    Failed to verify captcha

    Cancel Submit
    im a certified marine tech and i use that oil in all lower units, volvo, mercruiser, mercury, johnson, evinrude, honda, ect
    Bottom Line

    Yes, I would recommend this to a friend.
    Was this review helpful?

    YES (0) NO (0)
  • 5 star rating
    Marine gear lube
    By  DAVE,  a  Verified Buyer  on  August 26, 2025

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    Put this in an older outboard I recently got, shifting is quiet and smooth
    Bottom Line

    Yes, I would recommend this to a friend.
    Was this review helpful?

    YES (0) NO (0)
  • 5 star rating
    How does one review a gear lube?
    By  ALAN,  a  Verified Buyer  from  Alberta  on  August 22, 2025

    Open report issue form

    Describe the issue

    Failed to verify captcha

    Cancel Submit
    I don’t know how to review a marine gear lube. I am hoping the good people at Amsoil make a good product, but honestly, I have no way of knowing for sure. However, the packaging is the best compared to other bottles of gear lube I have used. It made filling the gear box much easier and for this I gave 5 stars.
    Bottom Line

    Yes, I would recommend this to a friend.
    Was this review helpful?

    YES (0) NO (0)
  • 5 star rating
    Amsoil marine gear lube
    By  JEFF,  a  Verified Buyer  from  Myrtle Beach, SC  on  August 01, 2025

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    Describe the issue

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    Cancel Submit
    At first appearance this product may be mistaken as just normal gear lube. WRONG, it takes a chemical to remove from your hands so just imagine how well it is protecting the internals of your lower unit! Will use as long as I have a boat! Amsoil rocks!
    Bottom Line

    Yes, I would recommend this to a friend.
    Was this review helpful?

    YES (0) NO (0)
  • 5 star rating
    Glad to get it in my new Merc 90
    By  RANDY,  a  Verified Buyer  from  Hartland Mich  on  July 30, 2025

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    Brand new 2025 Mercury 90. Peace of mind now that break in is complete and Amsoil is in. c”,)
    Bottom Line

    Yes, I would recommend this to a friend.
    Was this review helpful?

    YES (0) NO (0)