How to Choose the Right Engine Oil for Your Vehicle

Engine oil is the lifeblood of your vehicle. Choose the wrong type and you risk accelerated wear, reduced fuel economy, and costly engine damage. Choose the right one and your engine can run smoothly for hundreds of thousands of miles.

Here is everything you need to know to make the right call at the parts counter.

Oil does far more than lubricate moving parts. It:

• Reduces friction between metal components
• Carries heat away from the combustion chamber
• Suspends contaminants and carries them to the filter
• Prevents corrosion on internal metal surfaces
• Seals gaps between pistons and cylinder walls

When oil breaks down or is the wrong type, all of these functions suffer simultaneously.

The numbers on an oil bottle — like 5W-30 or 10W-40 — describe viscosity, which is the oil's resistance to flow.

• The first number (e.g., 5W): Winter viscosity. Lower numbers flow better in cold temperatures, protecting your engine on cold starts.
• The second number (e.g., 30): Operating viscosity at normal engine temperature. Higher numbers are thicker at heat.

A 5W-30 oil flows easily in winter cold and maintains adequate thickness when the engine is hot. A 10W-40 is slightly thicker at operating temperature — better for older, higher-mileage engines.

Always check your owner's manual first. The manufacturer specifies the exact viscosity grade for your engine. Using a different grade voids many warranties and can cause real damage.

Common recommendations by climate:

• Cold climates: 0W-20 or 5W-20
• Moderate climates: 5W-30
• Hot climates or older engines: 10W-30 or 10W-40

Refined from crude oil. Adequate for older vehicles and engines with simple designs. Requires more frequent changes (every 3,000–5,000 miles).

Best for: Older vehicles, low-mileage drivers, budget-conscious maintenance.

Engineered molecules designed for maximum performance and protection. Lasts longer, performs better in extremes, and keeps engines cleaner.

Best for: Modern vehicles, turbocharged engines, performance cars, extreme climates.

A mix of conventional and synthetic base oils. Offers better protection than conventional at a lower cost than full synthetic.

Best for: Trucks, SUVs, vehicles under moderate to heavy loads.

Formulated with seal conditioners and additional detergents for engines with over 75,000 miles. Helps reduce oil consumption and minor leaks.

Best for: Any vehicle over 75,000 miles showing signs of wear or minor seepage.

Look for these symbols on the bottle:

• API Starburst (SP, SN, SM): American Petroleum Institute certification. "SP" is the current top rating for gasoline engines.
• ILSAC GF-6: International standard for fuel economy and engine protection. Required by many modern manufacturers.

Never use oil that does not meet your manufacturer's specified certification.

Modern full synthetic oils can last 7,500 to 15,000 miles between changes, depending on driving conditions. Conventional oil should be changed every 3,000 to 5,000 miles.

Change more frequently if you:

• Drive mostly short trips under 5 miles
• Tow or haul heavy loads regularly
• Drive in dusty or extreme temperature conditions
• Have a turbocharged engine

1. Open your owner's manual — find the recommended viscosity grade
2. Check mileage — over 75,000 miles? Consider high-mileage formula
3. Consider your climate — colder winters call for lower W ratings
4. Choose your type — synthetic for modern engines, conventional for older ones
5. Verify certification — match the API/ILSAC spec your manufacturer requires

The right engine oil is the one your manufacturer recommends. Start there, then factor in your mileage, climate, and driving habits. When in doubt, full synthetic is almost always the safer choice for modern engines.

Need the right oil or filter for your vehicle? Browse TFI Parts' full selection of engine oils, oil filters, and drain plugs — all in stock with same-day shipping on orders before 3PM.