Can Gear Oil Be Used as Engine Oil?
2 Answers
Gear oil cannot be used as engine oil because their requirements differ in terms of inspection, viscosity grades, and other properties. Engine oil can withstand high temperatures (engine temperatures are very high), whereas gear oil cannot endure such high temperatures. It cannot achieve the same effects as engine oil and may negatively impact the vehicle's performance. Gear oil refers to the lubricant used in automotive mechanical transmissions, differential gears, and transmission mechanisms. It is formulated from refined base oils with additives such as antioxidants, anti-corrosion agents, rust inhibitors, anti-foaming agents, and extreme-pressure anti-wear agents. As a result, it provides excellent lubrication performance. Like other lubricants, it reduces friction, cools, cleans, seals, prevents rust, and reduces noise. However, its working conditions differ from those of engine oil, leading to different performance requirements. Requirements for gear oil usage: Gear oil must have excellent lubricity and high load-carrying capacity, appropriate viscosity with good viscosity-temperature characteristics, good low-temperature fluidity, strong anti-corrosion and oxidation resistance, and effective anti-foaming properties.
I don't think they can be casually interchanged – gear oil is definitely not a substitute for engine oil. Once, my car's engine started making strange noises, and the shop inspection revealed that someone had added gear oil as an emergency measure, which resulted in insufficient oil pressure and uneven lubrication. Gear oil is too viscous; it can't flow properly under the high temperatures of engine operation, potentially clogging oil passages and accelerating component wear. Engine oil, on the other hand, is specifically formulated for high-temperature cleaning, designed to remove carbon deposits and reduce wear. Gear oil is better suited for high-torque environments like transmissions or differentials. While it might work temporarily in a pinch, long-term use can destroy the engine, leading to expensive repairs. That's why I always strictly follow the manual for oil selection during maintenance to avoid small mistakes causing major damage. Spending a bit more on genuine engine oil is far better than dealing with towing and engine replacement costs later.
