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?” or even, "Does it matter what oil I put in my car?" 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!
WHAT MOTOR OIL SHOULD I USE IN MY CAR?
The best source of information is your vehicle owner’s manual. The manual will provide the necessary details on the proper oil viscosity grade (e.g. SAE 0W-20, SAE 5W-20, SAE 5W-30 or other) as well as the performance specification. Specifications will generally refer to ILSAC performance categories (such as GF-5 or GF-6) and/or API performance categories (Such as API SN, SN PLUS, SP). In these cases, there may also be pictures or symbols, developed by API , that you will find on motor oil labels. These can be used with the viscosity grades requirement, to confirm the proper choice. See examples below
Where OEMs have specific motor oil performance recommendations certain approvals may be necessary and these will be identified in owner manuals. Examples include GM dexos specifications which include a licensed logo found on motor oil labels (see below) as well as motor oil for European vehicles. European manufacturers specify the proper motor oil through their own specifications which in most cases involve motor oil brand approvals. Examples include Mercedes Benz 229.5, VW 502 00 and 505 00 and BMW Long-Life 01.
In addition to the right oil, one should always change the oil at the frequency recommended in the owner’s manual or as identified by the oil life indicator on the car’s dashboard.
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