Bel-Ray Engine Oil & Bel-Ray Gear Oil – Differences Explained

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While we all know the benefits of a good engine oil, the advantages of a gear oil are often overlooked because people don’t know the different requirements of lubricating an engine compared to a gearbox. Gear oil is specifically formulated to protect gearboxes and clutches. High quality gear oils must lubricate, cool and protect gears as well as keep contaminates from harming the surfaces inside your gearbox. The gear oil protects against scoring, scuffing and pitting, reduces noise and helps improve shifting, all of which means your gearbox will run smoother, quieter, and cleaner for longer.

While Bel-Ray 4t oils are all extremely good at protecting your gearbox and engine, there is a real advantage in using gear oils where possible. Motor oils have additives designed to protect the top end of a 4-stroke motor They are designed to help metal surfaces slide past each other, and are formulated using additives designed to clean and remove pollutants that are created during the burning of fuel. Some of the additives found in JASO MA and lower classified oils limit the performance of wet clutches. For that reason, for best clutch performance and life you should be using a JASO MA2 product or a gear oil where possible.

So what are the applications for Bel-Ray Gear Saver Transmission Oil? Bel-Ray Gear Saver Transmission Oil 75W and 80W, as well as Bel-Ray Thumper Gear Saver Transmission Oil 80W-85, can be used in all separate motorcycle gear boxes where it does not lubricate the top end of an engine. The most common example of separate transmission and wet clutch oil is found in 2-stroke motors. You can also use it for some 4-stroke engines that have separate gear oil and engine oil compartments such as the Honda CRF 250 and 450s. The viscosity of the gear oil also must be considered. Most commonly, engines up to 125cc use a 75W; anything bigger usually calls for the 80W or Bel-Ray Thumper Gear Saver Transmission Oil 80W-85.

A common misconception about gear oils relates to the SAE rating of the product, what most people don’t realize is that the SAE classification for gear oil and engine oils are different! The most common mistake is the belief that the viscosity of SAE 80W gear oil is much thicker than the viscosity of SAE 10W-40 motor oil. This is absolutely incorrect! A 10W-40 motor oil’s viscosity is actually similar to the viscosity of 80W gear oil, and the viscosity of SAE 10W-30 is similar to 75W gear oil.

So, if you have a 2-stroke or you have a 4-stroke engine with separate gear box oil and engine oil you will be better off using a specific gear oil designed to protect your gears rather than an engine oil that has to protect both engine and gearbox.

In addition to Bel-Ray Gear Saver Transmission Oil 75W, 80W and Bel-Ray Thumper Gear Saver Transmission Oil 80W-85, we also produce Bel-Ray Gear Saver Hypoid Gear Oil. Transmissions without wet clutches and final drives require different oil that provides the lubrication needed for the sliding motion of the hypoid gears. Bel-Ray Gear Saver Hypoid Gear Oil is GL-5 rated meaning it contains the proper additives to provide the lubrication needed for the sliding motion of the gears. Hypoid gears are used to transmit power from the driveline to the axle shafts and don’t have a wet clutch, therefore we are able to add special Extreme Pressure additives that would normally not be available in other gear oils. Most common applications require GL-5 80W-90, however for very heavily loaded transmissions and final drives we also produce Gl-5 85W-140. Both of these products can be used in automotive applications as they are API service rated GL-5. Bel-Ray Gear Saver Hypoid Gear Oil is not to be used in a wet clutch application because the additives can cause clutch slippage.

As you can see, there are many reasons why gear oil will work better in the right application. With the proper gear oil you will get better clutch performance, longer clutch life, smoother shifting, longer life of your gearbox, less gear noise, less slip and fewer deposits left behind in your engine. If you are unfamiliar with the requirements of a specific application, you can consult the Bel-Ray Lubricant Advisor on the Bel-Ray web site at, where you can enter your make and model and get the right products for your motorcycle. You may find the following information helpful, as well.

HYPOID GEAR OILS:• Bel-Ray Gear Saver Hypoid Gear Oil 80W-90 (99230)• Bel-Ray Gear Saver Hypoid Gear Oil 85W-140 (99234)