All about motor oil
Engine oil does four big jobs: it lubricates moving parts, helps carry heat away, keeps contaminants suspended so they can be filtered out, and protects against corrosion and wear. Choosing the right oil (and changing it on time) is one of the simplest ways to maximize engine life.
Common oil types
- Conventional: a refined petroleum base oil with an additive package. Often the lowest-cost option.
- Synthetic blend: a mix of conventional and synthetic base oils. A middle ground for cost and performance.
- Full synthetic: engineered base oils with strong high-temperature stability and cold-flow performance. Common in modern engines and turbo applications.
- High-mileage: formulated for older engines and seals, typically with conditioners and an additive balance aimed at reducing consumption and seepage.
Viscosity grades (0W-20, 5W-30, etc.)
Viscosity is simply how “thick” an oil is at different temperatures. Multigrade oils have two ratings:
- The first number + W (“winter”) reflects cold-temperature flow. Lower numbers generally flow better at cold start.
- The second number reflects viscosity at operating temperature. Higher numbers generally stay thicker when hot.
Always start with the viscosity listed in your owner’s manual. Modern engines are built with tight clearances, and the manufacturer’s recommended viscosity is part of the design.
Specifications and approvals (API / ILSAC / ACEA)
Beyond viscosity, oils meet performance standards. In North America you’ll commonly see API (e.g., API SP) and ILSAC (e.g., GF-6). Some vehicles require additional manufacturer approvals (common with many European makes). If your manual calls for a specific spec or approval, make sure it’s listed on the bottle.
Additives and detergents
Modern oils contain carefully balanced additives: detergents/dispersants to keep engines clean, anti-wear agents, antioxidants, friction modifiers, and more. Because this package is balanced, adding extra aftermarket additives is rarely necessary and can sometimes do more harm than good.
Oil change intervals
Change intervals depend on the engine, oil type, driving conditions, and whether your vehicle has an oil life monitor. Frequent short trips, heavy loads, towing, dusty conditions, and lots of idling typically count as “severe service” and may require shorter intervals. When in doubt, follow your manual and oil life monitor (if equipped).
Why the oil filter matters
Your oil filter traps contaminants (soot, metal particles, dirt) so they don’t circulate through the engine. Filters also include important features like anti-drainback valves (to reduce dry starts) and bypass valves (to keep oil flowing if the media is restricted). Using the correct OEM-equivalent filter for your engine matters—fitment and valve settings can differ between part numbers.
Quick checklist
- Use the viscosity and specifications listed in your owner’s manual.
- Change oil on time for your driving conditions.
- Use the correct filter part number for your engine.
- If you’re unsure, look up your OEM filter on the home page or browse by make.
Disclaimer: This page is general information and is not a substitute for your vehicle’s owner’s manual or professional advice. Always follow manufacturer requirements for your specific vehicle.