What Happens If Gear Oil Is Used as Engine Oil?

[DiBradley]

Using gear oil as engine oil will cause engine overheating and rapid carbon buildup, leading to piston damage. The differences between gear oil and engine oil are mainly reflected in the following aspects: 1. Different working environments: Gear oil is mainly used in transmissions, reducers, and differentials, while engine oil is primarily used in automobile engines. Since gear teeth engage through direct contact, gear oil must have extremely high viscosity specifications; otherwise, it cannot form an oil film at the gear engagement points. In contrast, engine lubrication points mostly involve surface contact without the extreme high pressure generated during gear engagement, so engine oil has lower viscosity requirements. 2. Different emphases: Gear oil focuses on protecting gears under high temperatures, while engine oil emphasizes low-temperature fluidity. Additionally, gear oil is strongly alkaline, whereas engine oil is weakly alkaline.

[StSpencer]

Oh, I've encountered this issue several times. Accidentally adding gear oil to the engine is practically playing with fire. Gear oil is too thick, like syrup, and completely unsuitable for the engine's lubrication system. It causes the oil pump to struggle, possibly failing to draw oil, directly leaving the engine without lubrication protection. Friction between components increases, and parts like pistons and bearings may overheat and wear out. The engine might start making rattling noises or even stall suddenly. Driving just a few hundred meters could trigger warning lights on the dashboard, with the temperature gauge soaring alarmingly. The worst part is, over time, the seals could be damaged, leading to a host of oil leakage problems. Stop the car immediately and don't start it. Find a professional repair shop to drain the oil, replace it with standard engine oil, and conduct a thorough inspection. Otherwise, trying to save a little money now could cost you thousands in engine repairs later—what a terrible trade-off.

[JadeMarie]

As someone who frequently tinkers with cars, I think adding the wrong gear oil to the engine is just terrible. Gear oil is meant for the transmission; it's too thick and not suitable for the rapid flow needed to cool and lubricate the engine internals. If you put it in the engine, the oil pump might get stuck, and the lubrication effect will be significantly reduced. You'll notice slower acceleration, engine noise as loud as a tractor, and possibly a sharp increase in fuel consumption. Even short drives could lead to overheating, misfires, and the check engine light coming on. Fixing it is a hassle—not only do you have to change the oil, but you might also need to check the oil passages for any residual damage. Remember to check the label carefully before adding oil next time. Don’t cut corners; put in a bit more effort to avoid such careless mistakes. Safety first, after all.

[VonReese]

When I first started learning to drive, I almost made this mistake—gear oil must never be added to the engine. It's thick and sticky, unlike engine oil which is much smoother. The engine needs a thin protective layer of oil. If you add the wrong oil, the engine will struggle to run, possibly causing shaking or stalling. Shortly after starting and driving a short distance, the dashboard will likely alert you, indicating insufficient oil pressure. Stop the car immediately and avoid further operation to prevent costly engine wear. It's best to seek help from a repair shop right away to flush and replace the oil, avoiding more serious issues down the line.