Why do we use multigrade oils in cars today?
Multigrade engine oils are designed to lubricate engines across a broad temperature range, providing reliable protection during cold starts and steady performance when the engine is hot, all with a single oil grade.
What multigrade oil is and how it works
Multigrade oils blend a base lubricant with viscosity index (VI) modifiers so the oil can flow easily when cold yet retain a protective thickness at high temperatures. This allows a single oil to perform well from winter starts to summer highway cruising, reducing wear and improving overall efficiency. The following points summarize how they function and what you typically encounter in the market.
- VI modifiers are long-chain polymers that thicken the oil as temperatures rise, helping maintain a stable lubricating film at high engine speeds and temps.
- At low temperatures, the base oil remains sufficiently fluid to promote easier starting and quicker oil circulation.
- Common multigrade grades you’ll see include 0W-20, 5W-30, 10W-40, and similar pairings; the first number with a “W” indicates winter (cold) performance, while the second number indicates hot-weather viscosity.
- Oils can be conventional, semi-synthetic, or fully synthetic; synthetics often offer better shear stability, oxidation resistance, and longer-term protection.
In short, multigrade oils provide reliable lubrication across temperature ranges, enabling easier starts, robust protection, and improved efficiency with a single recommended grade.
Why multigrade oils matter in modern cars
Car manufacturers rely on multigrade oils today because engines operate across a wide range of temperatures and conditions, from frigid starts to hot, long-duration driving. The list below explains the practical benefits drivers can expect in everyday use.
- Cold-start protection: the oil flows quickly enough to coat bearings during start-up, reducing metal-to-metal wear.
- Viscosity management across temperatures: the oil maintains an adequate film thickness when hot, preventing scuffing and excessive wear.
- Fuel economy and reduced drag: lower-viscosity startup oil reduces parasitic drag, contributing to better mpg and lower emissions.
- Turbocharged and high-load engines: thin oils deliver faster lubrication to turbo bearings and high-load components during rapid temperature changes.
- Engine cleanliness and durability: stable viscosity helps control deposits and oxidation, supporting longer engine life and more consistent oil-change intervals.
- Standards and OEM alignment: multigrade oils are formulated to meet API, ILSAC, ACEA standards and OEM approvals, ensuring compatibility with modern engines and emissions systems.
In practice, these benefits translate to smoother starts, better efficiency, and reliable lubrication across the engine’s operating envelope, which is why multigrade oils are commonplace in today’s vehicles.
Choosing the right multigrade oil for your car
Selecting the correct viscosity and oil type involves checking the vehicle’s specifications, climate, and driving habits. The steps below help guide a sensible choice that aligns with the manufacturer’s requirements.
- Consult the owner’s manual to identify the recommended viscosity (for example, 0W-20, 5W-30, etc.) and any OEM approvals.
- Consider climate and typical driving conditions (frequent cold starts, hot weather, short trips, or long highway runs).
- Choose between conventional, semi-synthetic, or fully synthetic oils based on engine design, age, driving style, and budget.
- Ensure the oil meets relevant standards (API SP or newer, ILSAC GF-6 or newer, ACEA grades) and any OEM-specific approvals.
- Follow recommended change intervals and use a compatible oil filter to maintain performance and protection.
Following these steps helps ensure you select an oil that delivers the intended protection, efficiency, and durability for your vehicle.
Standards and performance labels to look for
Automotive oils are certified to international standards that signal performance across temperature, wear protection, and emissions compatibility. Look for the following indicators on the bottle or in product literature.
- API: SP or newer, indicating modern wear protection, sludge control, and oxidation resistance.
- ILSAC: GF-6 (GF-6A/GF-6B) and newer, targeting fuel economy, cold-start protection, and emissions performance.
- ACEA: European engine requirements (e.g., A3/B4, C3) relevant to the engine type and vehicle class.
- OEM approvals: certain brands require specific approvals or endorsements beyond generic API/ILSAC/ACEA labels.
Always cross-check the oil specification with your vehicle’s manual and opt for oils with the appropriate certifications for your engine.
Summary
Multigrade oils offer a practical solution for lubricating modern engines across a wide temperature range. They support reliable cold starts, maintain protective lubrication as engines heat up, and help improve fuel economy, all while meeting OEM standards. When choosing oil, follow the manufacturer’s recommendations, consider climate and driving patterns, and verify that the oil carries the appropriate API, ILSAC, ACEA, and OEM approvals. As engines continue to adopt tighter tolerances and advanced emissions systems, high-quality synthetic or synthetic-blend multigrade oils remain the standard choice for durable, efficient operation.
Why is all oil synthetic now?
Most new cars require synthetic because the components are tight fitting and need a thinner oil, but older engines don't have the same tight tolerances, so they're not so picky.
What is the advantage of using multi-grade oil in your car?
A multigrade oil offers better engine protection at low and high temperature as it maintains optimum viscosity across the whole engine operating temperature range.
Why do modern cars use thinner oil?
Newer engines are designed for thinner oils. The ports that oil flows throw are thinner because of it. Engineers have done with because thinner oil takes less energy to move, thus engines with thinner oil are more fuel efficient.
Is multigrade oil good for cars?
At the moment, the vast majority of oils used in the automotive industry are multigrade oils. These oils have a very high viscosity index, which allows their viscosity to be low enough at start-up, when conditions are cold, and high enough when the vehicle is running, when the temperature is very high.
