What Kind of Oil Does My Car Take?
If you’ve recently been to the motor oil aisle at your local auto parts store, you know there are a lot of options. You’ll see bottles with lots of numbers, synthetic oil and conventional. You’ve probably wondered “what is the difference in oil types?” and “which car oil is best?” Trust Castrol for expert advice to help you make sense of it all.
You don’t have to be an expert to choose your own oil. In fact, the Castrol Motor Oil Finder can easily match the right oil to your specific vehicle. But there are some things that are good to know. So read on to learn about the types of oil and the differences in grades, which measure viscosity and performance.
What are the three types of car oil?
Here’s a brief overview of the three primary car oil types: conventional, synthetic and synthetic blend. You’ll also want to read this Castrol article for a deeper dive on conventional vs synthetic.
So what do those motor oil letters and numbers mean?
Not every engine or vehicle needs the same type of oil. That’s why the Society of Automotive Engineers (SAE) created a standard rating system to categorize the different grades. The SAE rating is the number and letter combination you see on bottles of oil, such as 10W-60 or 5W-30. These are measures of an oil’s viscosity.
Viscosity and oil performance
Viscosity is a measure of a fluid’s thickness and resistance to flow. For example, water is thinner, with a much lower viscosity than honey. Motor oil is no different. The SAE grade of an oil includes two numbers and a letter. Let’s use 10W-30 as an example:
The first number, 10, ends with the letter W. That stands for Winter and refers to how the oil will flow when it is cold, such as when the engine is first getting started.
The second number, 30, refers to how the oil will flow at higher temperatures, such as when the engine is at normal operating temperature.
The smaller the number, the thinner the oil. For instance, compared to our 10W-30 example, a 5W-30 oil will thicken less in cold weather. On the flip side, during summer months and in warmer regions, a 5W-40 oil will thin at a slower rate than a 5W-30 oil.
Think of it this way: engine oils naturally thicken as they cool, and thin as they’re heated. Therefore:
- Thin, low viscosity oils (lower numbers) flow easier to protect engine parts at cold temperatures.
- Thicker, high viscosity oils (higher numbers) are typically better at protecting engines at warmer temperatures.
How do i know what oil to put in my car?
Now that you have the basic facts about motor oil, you probably want to know what the best oil type for your vehicle is. It’s pretty easy to make the right choice when you consider these key factors:
- Your specific vehicle
- Your climate
- How often you want to change the oil
Refer to your vehicle’s user manual which will list the recommended oil. Or use the Castrol Motor Oil Finder. It’s an easy online tool. Just enter your vehicle’s info and we’ll do the rest!
Castrol® EDGE®
Unlock maximum engine performance:
- 3X stronger than the leading full synthetic1
- 10X better high stress performance2
- 6X better wear protection3
- Protection for 20,000 miles between oil changes
- Improves fuel economy (0W grades)
- Carbon Neutral4
1. In viscosity breakdown as measured in Kurt Orbahn test on 5W-30 grade
2. As measured in the Sequence IX test under high load/torque conditions vs. API SP limits
3. Based on Seq IVA vs. latest test limits
4. In accordance with PAS2060. www.castrol.com/us/cneutral for details on our Path 360 sustainability program
CASTROL® GTX® FULL SYNTHETIC
Provides maximum protection to help extend engine life:
- Superior wear protection on critical engine parts (6X better wearprotection)5
- Superior sludge cleaning and protection against new formation (1.3Xbetter sludge protection)6
- Full synthetic formula provides thermal and oxidation stability
- Superior level of protection against viscosity breakdown
5. Based on Seq IVA test vs. latest test limits
6. Based on Seq VH vs. API SP test limits