Engine oil lubricates, cools and cleans the engine, and the wrong choice can raise wear and cut efficiency. The good news is that your owner's manual tells you exactly what your engine needs. This guide explains how to read it and how to choose between the options.
Start with the owner's manual
The manual lists the viscosity grade (such as 5W-30 or 0W-20), the quality standard (such as API SP or ILSAC GF-6) and the oil capacity. Use the grade the maker specifies. Many engines are designed around a thin oil to improve efficiency and cold starts, so do not assume thicker is better.
How to read viscosity
In 5W-30, the first number with the W (for winter) shows how well the oil flows when cold: the lower the number, the easier it flows at start-up. The second number shows how thick the oil is at normal operating temperature. A 5W-30 flows like a 5-weight oil in the cold and protects like a 30-weight oil when hot.
Conventional, blend or full synthetic
- Conventional: refined from crude oil, the lowest cost, with shorter change intervals. Fine for simple engines with light use.
- Synthetic blend: a mix that offers better protection than conventional at a moderate price.
- Full synthetic: engineered for stability at high and low temperatures, with better protection against sludge and wear and longer drain intervals. Required by many modern, turbocharged and high-output engines.
- High-mileage: oil with seal conditioners for engines with many miles, often with a synthetic or blend base.
Special cases
- Turbocharged and direct-injection engines generally call for full synthetic oil.
- Diesel engines need oil with a diesel rating, such as API CK-4, rather than a gasoline-only oil.
- Towing, dust and short trips count as severe service and shorten the change interval.
How often to change it
Follow the interval in the manual, or the oil-life monitor if your vehicle has one. Typical intervals range from about 5,000 miles with conventional oil to 7,500 to 10,000 miles with synthetic, but your engine and driving matter more than any general number. Check the oil level on the dipstick regularly, because an engine that burns or leaks oil can run low between changes.
Common questions
Can I mix different oils?
In an emergency, topping up with a compatible oil is fine. For regular use, stay with one grade and type.
Is synthetic oil worth the cost?
For most modern engines, yes: longer intervals and better protection often offset the price. Use it whenever the manual calls for it.
What if I use the wrong viscosity?
The engine will usually run, but wear, fuel economy and cold starts can suffer. Drain and refill with the correct oil.
Where to buy
Shop oils, fluids and sealers. For the filter that goes with the oil, read how to choose an oil filter. We are an authorized dealer for every brand we sell, shipping is free anywhere in the USA, and returns are accepted within 60 days (unused, in the original packaging) and return shipping is free. Not sure what fits your vehicle? Contact our support team and we will help you check before you order.