Using engine oil that differs from the manufacturer's recommendation can have various effects on your vehicle's performance, efficiency, and long-term health. While "different" can mean various things – including different types (like conventional vs. synthetic), different specifications (like API or ACEA ratings), or different grades – one significant effect, particularly concerning viscosity, is on fuel economy.
Effects of Using Different Engine Oil Viscosity
Engine oil viscosity refers to its resistance to flow. Oil needs to be thin enough to flow easily through the engine at low temperatures (cold start) but thick enough to maintain a protective film between moving parts at high temperatures. Manufacturers specify a particular viscosity grade (e.g., 5W-30, 10W-40) based on the engine's design and operating conditions.
Using an engine oil of higher viscosity than recommended by the manufacturer can lead to a decrease in fuel economy.
Why does this happen? According to automotive experts, thick oils increase the level of resistance of the engine's moving parts, like pistons. The engine has to work harder to overcome this increased resistance, much like trying to push through thick mud compared to water. This extra effort requires the engine to burn more fuel, hence leading to reduced fuel efficiency.
| Viscosity Difference | Potential Effect | Mechanism |
|---|---|---|
| Higher Viscosity | Decreased Fuel Economy | Increases internal friction/resistance, forcing the engine to work harder. |
| Higher Viscosity | Potentially Slower Oil Flow (Cold) | May not circulate quickly enough on startup, increasing wear before oil reaches all parts. |
| Lower Viscosity | Potentially Reduced Protection (Hot) | May not maintain a sufficient protective film at high temperatures/pressures, leading to increased wear. |
Other Ways Engine Oil Can Be "Different"
Beyond viscosity, engine oil can also differ in:
- Type: Conventional, Synthetic Blend, Full Synthetic. Synthetic oils generally offer better protection and performance over a wider temperature range but must meet the manufacturer's required specifications.
- Specification/Rating: These ratings (like API SN, CK-4, or ACEA A3/B4, C3) indicate the oil's performance standards regarding wear protection, deposit control, emissions compatibility, etc. Using oil with the wrong specification can cause harm to specific engine components or emissions systems.
- Additives: Different oils have varying additive packages designed for specific purposes (e.g., high mileage, diesel engines, turbo protection).
Using oil that doesn't meet the manufacturer's required type, grade, and specification can lead to various issues, including increased engine wear, deposit build-up, reduced performance, and potentially damage to critical components.
Why Following Manufacturer Recommendations is Crucial
The most important rule for choosing engine oil is to always consult your vehicle's owner's manual. Manufacturers spend significant resources determining the optimal oil requirements for their engines to ensure longevity, performance, and efficiency. Using an oil that deviates from these recommendations, especially in terms of viscosity or specification, can negate these benefits and potentially cause damage.
Using the correct engine oil ensures proper lubrication, cooling, cleaning, and sealing of the engine's internal parts, allowing it to operate as intended.
