Engine Oil
* Purpose: To lubricate and cool internal combustion engines.
* Viscosity: Thinner than gear oil, allowing for easier flow through engine parts.
* Additives: Contain detergents, dispersants, anti-wear agents, and anti-oxidants to protect engine components from wear, sludge, and corrosion.
* Operating Conditions: Subject to high temperatures and pressures, rapid changes in speed, and potential contamination with combustion byproducts.
* Types: Conventional, synthetic, semi-synthetic, based on different base oil compositions and additive packages.
Gear Oil
* Purpose: To lubricate gears and bearings in transmissions, differentials, and other gear systems.
* Viscosity: Typically thicker than engine oil, providing a strong protective film for gear teeth.
* Additives: Contains extreme pressure (EP) additives to resist wear and prevent metal-to-metal contact under heavy loads.
* Operating Conditions: Operates under high loads and pressures, often with slow speeds and minimal temperature variation.
* Types: Hypoid, GL-4, GL-5, based on different viscosity grades and EP additive levels.
Key Differences in a Nutshell:
| Feature | Engine Oil | Gear Oil |
|---|---|---|
| Viscosity | Thinner | Thicker |
| Additives | Detergents, dispersants, anti-wear, anti-oxidants | Extreme pressure (EP) additives |
| Operating Conditions | High temperatures, pressures, rapid changes | High loads, pressures, slow speeds |
| Application | Internal combustion engines | Transmissions, differentials, gear systems |
Mixing Engine and Gear Oil:
It is extremely unwise to mix engine oil and gear oil. They have different chemical compositions and additive packages. Using the wrong oil can lead to:
* Premature wear: The wrong viscosity or lack of necessary additives can lead to increased wear and damage to components.
* Friction and heat: Mismatched oils can increase friction and heat, potentially leading to component failure.
* Clogging and sludge: Incompatible additives can react, leading to deposits and clogging in the system.
Always refer to your vehicle's owner's manual for the correct type and viscosity of oil to use.
