The Mercury 18 XD typically requires about 1 quart of gear lube for the lower unit. It's essential to use the appropriate type of gear lube recommended by the manufacturer. Always check the owner's manual for specific requirements and ensure the lower unit is filled to the correct level for optimal performance.
For a 90hp Mercury two-stroke outboard, you should use a high-quality lower unit gear lube specifically designed for outboard motors. Mercury recommends using their own brand of gear lube, such as Mercury High-Performance Gear Lube or Quicksilver Gear Lube, which offer excellent protection against wear and corrosion. Always check the owner's manual for specific recommendations regarding viscosity and any additional requirements.
Mercury® Marine High-Performance Gear Lube from Basspro
If the horsepower of your Mercury outboard lower unit is 75 and below, SAE 80W90 Gear Lube is recommended.
For the Mercury 9.8 110 lower end unit, it's recommended to use a high-quality gear lubricant specifically designed for marine applications. Typically, a 90-weight gear oil, such as Mercury Gear Lube or an equivalent marine gear oil, is suitable. Always check the owner's manual for specific recommendations and any updates on lubrication requirements.
Using Valvoline 75W-90 synthetic oil in the lower unit of a Mercury outboard is generally not recommended unless it meets the manufacturer's specifications. Mercury typically specifies its own gear lube, often requiring a specific type such as Mercury High-Performance Gear Lube or a similar product. Always consult your owner's manual for the correct type of oil to ensure optimal performance and to maintain warranty coverage.
For a Mercury outboard 2-stroke motor, it's recommended to use a high-quality lower unit gear oil specifically designed for marine applications. The typical choice is a 90-weight gear oil, such as Mercury's own High Performance Gear Lube or similar products that meet API GL-5 specifications. Always check your owner's manual for the exact specifications and recommendations for your specific model.
Usually you fill it to the bottom of the hole.
Mercury Premium gear lube is caramel-clear in color. It should be changed every year or 100 hours of use. If it gets old and smelly it should be changed. If you see white streaks you have water leaking in through a bad seal. Mercury High performance Gear lube is blue/green-clear. See more at sterndrives.com
To check the gear lube on a yard machine tiller, first ensure the tiller is on a level surface and turned off. Locate the gear lube fill plug, usually on the side of the gear case, and remove it using the appropriate tool. Inspect the lube level; it should be just below the fill hole. If needed, add the recommended gear lube until it reaches the proper level, then securely replace the fill plug.
Quicksilver 80W-90 Premium Gear Lube
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I had used a high performance gear lube quick silver marine lubricant it is not expensive and works very well