Mercury – Quicksilver 85W-140 Motorcycle Transmission Oil | Heavy-Duty Gear Protection | High-Viscosity Formula | 8M0128385

Overview

There’s a certain reassurance that comes from riding a big V-twin — that deep, rolling pulse, the steady pull, the sense that the machine underneath you was built to work hard. But those engines, especially the ones with separate gear cases, demand oil that can stand up to real heat, real load, and real miles. Quicksilver 85W-140 Motorcycle Transmission Oil delivers exactly that. It’s the kind of oil you trust when you’re pushing through long stretches of highway or winding your way up mountain grades, knowing your gears are staying cool, cushioned, and ready for more.

Key Features

• High-viscosity transmission oil for large air-cooled or liquid-cooled V-twin motorcycles
• Designed for shaft drive or separate clutch/transmission assemblies
• Offers maximum protection against wear, oxidation, and corrosion
• Meets or exceeds API GL-5 / MT-1 and SAE J236 standards
• Helps maintain consistent performance under extreme load and heat
• Packaged in a one-quart bottle for easy, clean service
• Not for use in wet-clutch systems

Engine & Compatibility

• Intended for large displacement V-twin motorcycles
• Works with both air-cooled and liquid-cooled V-twin engines
• Suitable for bikes that use separate gear cases or shaft drive systems
• Compatible with touring, cruiser, and heavy-duty long-distance motorcycles
• Approved for use without affecting manufacturer warranties

Performance & Practical Benefits

Riders who run bigger V-twins know the pressures these engines put on their gearboxes. Heat builds fast, especially during slow climbs or heavy two-up riding. Quicksilver’s 85W-140 formula is made for exactly those conditions. The thicker viscosity creates a strong, stable film that keeps gears running smoother and quieter, even when load and temperature spike. Instead of that harsh, metallic feel some oils allow, you get a more cushioned, controlled response when shifting.

The formula also resists oxidation, which helps the oil stay clean longer, avoiding the thickening and sludge that can wear gears prematurely. Corrosion protection matters just as much, especially for bikes that sit through winter or aren’t ridden daily. This oil coats internal surfaces with a protective layer that hangs on, even when the bike is stored. The result is a gearbox that feels more reliable, sounds healthier, and lasts longer — exactly what you want when your motorcycle is your escape, your weekend ritual, or your main ride.

Why Buy OEM

When you’re maintaining a machine that carries weight, heat, and torque the way a V-twin does, using a trusted, high-quality oil isn’t a luxury — it’s common sense. Quicksilver’s reputation comes from decades of engineering lubricants for marine environments where gears face brutal loads and constant exposure. That experience transfers directly into this motorcycle transmission oil. With strict performance standards, consistent viscosity retention, and proven durability, this Mercury Marine part number offers reliability many aftermarket oils simply can’t match. It’s a smart move for riders who want to protect their investment and avoid expensive repairs.

FAQ

Q1: Which systems does this transmission oil fit?

It’s formulated for motorcycles with separate gear cases or shaft drive systems, especially large V-twin engines.

Q2: What sets it apart from aftermarket oils?

The high-viscosity, extreme-pressure formula offers stronger wear protection and better resistance to heat, oxidation, and corrosion — all crucial for heavy V-twins.

Q3: How do I know if it’s right for my motorcycle?

If your bike uses a separate gear case and the manufacturer recommends 85W-140 gear oil, this part number is a reliable match. It is not for wet-clutch applications.

Q4: Is it suitable for extreme temperatures?

Yes. It handles both scorching climates and cooler conditions with stable viscosity and dependable performance.

Q5: Is installation straightforward?

Definitely. Changing gear oil is a simple maintenance task, and the one-quart bottle makes refilling clean and manageable.