Extreme Duty Marine Semi Synthetic 20W-50 Engine Oil

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Extreme Duty Marine Engine Oil Semi Synthetic SAE 20W-50

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Lucas Extreme Duty Marine Semi Synthetic 20W-50 Engine Oil is designed for use in high performance boats requiring the ultimate protection.

Lucas Extreme Duty Marine Semi Synthetic 20W-50 Engine Oil is manufactured with the highest quality paraffinic base oils and is fortified with an exclusive additive package containing high levels of Zinc, Moly and Phosphorus that provides a tougher, thicker additive film for maximum protection even under the most sever conditions. It lowers oil temperatures, extends oil life and minimizes metal fatigue.

Lucas Marine Semi Synthetic 20W-50 improves the film strength between the cylinder  wall and piston rings and slows oil burning while improving pressure levels in worn engines. It has good cold temperature properties and stands up to high operating temperatures. This product is compatible with methanol and all racing fuels.

Key Benefits

  • Excellent for use with supercharged, turbo charged or nitrous oxide high performance engines
  • Protects against rust and moisture during long periods of storage
  • Safely blends and is compatible with synthetic and non-synthetic oils
  • Dropping point 540 lbs
  • Provides rust and corrosion protection in both fresh water and salt water environments
  • Effective Water Resistance
  • Long Lasting
  • Resist Extreme Pressure
  • Extreme Friction Reducer


  • #10654 - 1 Quart (Case of 6) - 12 lbs
  • #10811 - 5 Quart (Case of 3) - 31 lbs
  • #10667 - 5 Gallon Pail (1 Pail) - 40 lbs
  • #10668 - 55 Gallon Drum (1 Drum) - 440 lbs


Product Spec Sheet Technical Data Sheet
Safety Data Sheet Safety Data Sheet
zinc Zinc Values

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Harry Sisson uses Lucas Semi-Synthetic Automatic Transmission Fluid for 1994 Olds 88

Dear Lucas Oil,

My son reported that his Olds 88 with 186,000 miles on it had developed a transmission problem: With each start in the morning, the transmission would not engage when moving the selector from Park to Drive. The only way it would engage was to move the selector into L1, and then back into Drive.

We performed the previous filter and partial fluid change 35,000 miles ago, and all was normal at that time. We were both not too hopeful, but thought we would give Lucas a try first, before submitting to over $1300 dollars of rebuilt transmission.

We dropped the transmission pan, inspected for debris, and found none. The fluid was fine, with no discoloration or odor. There was only the normal small amount of black film in the bottom of the pan, but absolutely no metal or synthetic particles. We even disassembled the old filter, and inspected it. Again, all was fine.

So, we installed a new filter, cleaned up the pan, magnet, and re-usable silicone gasket, reinstalled, replaced the seven quarts of fluid, and one bottle of Lucas automatic transmission additive.

To this day, the transmission is working perfectly. We are now eager to see just how many miles this transmission will go, now that we are using the Lucas, and "max-life Dexron III" fluid !!

Harry Sisson

Sheridan, WY

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