The Difference Between Gear Oil and Engine Oil

Consistent maintenance is critical for keeping your vehicle running smoothly, and keeping track of the fluids is part of that process. Depending on your vehicle’s mileage, your mechanic may suggest changing its gear oil. While most people are familiar with engine oil, gear oil gets changed so infrequently that many vehicle owners rarely handle it. While they both serve the same purpose—to lubricate and protect parts—they’re not the same thing. If you’re looking to keep your vehicle in top shape, learn the difference between gear and engine oil.

The Purpose of Engine Oil

Your engine contains many moving parts, all of which function in high heat. While these parts may be metal, they aren’t indestructible. Without engine oil, the parts would scrape against one another and quickly destroy an engine. Think about it like this—if you were to rub your fingertips together, the natural oils in your skin aid the glide. If your skin were to suddenly become sapped of its natural oils, rubbing your fingers together would hurt and damage the skin over time.

Engine oil also evenly distributes heat and traps contaminants, keeping your engine clean and protecting it from rust and corrosion.

The Purpose of Gear Oil

Gear oil lubricates the gear systems within your engine, such as the gearbox, transaxles, and transfer case. Gear and engine oils lubricate parts that would otherwise scrape against and destroy one another. However, there is much more to their formulation than just mineral oil. Additives within their formulation let the oil stabilize itself, allowing it to perform continuously despite the high demand from your engine.

Never put gear oil in an engine or vice versa.

The Main Differences Between Engine and Gear Oil

If engine and gear oil serve the same purpose, what’s the difference? It lies in their environment. A gearbox is cooler than an engine, but the pressure between moving gears is much higher than in an engine. Engine oil requires additives that stabilize the formulation in high heat, while gear oil requires a formulation that prevents it from breaking down under pressure.

In terms of temperature versus viscosity, oil will thin as it heats, damaging its ability to lubricate parts. Complex polymers within the formulation keep the oil thick, allowing it to do its job. If you used gear oil in an engine, it wouldn’t be able to handle the heat. It would quickly become useless. If you want to protect your vehicle and ensure its longevity, you have to use the right lubricants in the right places.