All about motor oils
Engineering Explained:
Will Thinner Oils Damage Your Engine?
Types of motor oil
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Synthetic or conventional?
What's the difference between synthetic and conventional motor oils? Find out about synthetic vs. conventional oils.
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Types of synthetic oil
Did you know that not all synthetic oils perform the same? Discover the differences and which is right for your car.
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High mileage motor oils
High mileage engines – those with more than 75,000 miles – face a number of potential problems that high mileage oil is specifically formulated to address.
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FAQs
Engine oils are currently classified by a two-letter code. Gasoline engine oil categories start with the letter S (originally designated "Spark Ignition" engine oils, we now associate the S with "Service"). Diesel engine oil categories start with the letter C (originally designated "Compression Ignition" engine oils, we now associate the C with "Commercial").
The second letter is simply a sequential designation of improving quality levels over time. In other words, when a new industry quality level is established, the next letter of the alphabet is used (so SN replaced SM). The letters "I" and "K" were purposefully skipped to eliminate potential confusion with other commonly used designations.
Motor oil basics
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Motor oil labels demystified
Find out what the numbers, letters, seals and other information on motor oil bottle labels mean.
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How oil filters work
What do oil filters do? How do you find the right filter? Learn all about oil filters.
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How to improve fuel economy
Find out how motor oil affects fuel economy, how it works within your engine’s mechanisms and more.
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Viscosity is a measure of a fluid's resistance to flow. A fluid with low viscosity flows easily and is often called "thin." Water is an example of a fluid with a relatively low viscosity. A fluid with high viscosity is often described as "thick." Maple syrup is an example of a fluid with a relatively high viscosity.
Your oil warning light can come on for a number of reasons, including low oil level, a failing oil pump, a faulty oil-pressure sensor, blockage in the oil system, excessive foaming of the oil and more. In all cases, you should shut down your engine as quickly as it is safe to do so. Continuing to operate your engine with low oil pressure can result in serious engine damage.
Oil change basics
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How to change your car's motor oil and filter
Changing your oil and filter is crucial for long engine life – and doing it yourself is relatively easy and inexpensive. Learn how.
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Where to get an oil change
Going to a service center or car dealer is the choice for many vehicle owners. We'll help you find a location.
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