What does SAE stand for?
You’ll see these three letters written on the bottle of your motor oil right before the viscosity grade. And if you don’t, you might want to skip that motor oil!
So, what is SAE oil?
And what does the SAE oil number indicate?
We’ll do our best to explain all this, and get into interpreting the SAE oil number. We’ll also answer some FAQs you might have about SAE.
This Article Contains:
- What Does SAE Stand For?
- What Is SAE Oil?
- What Is An SAE Oil Number?
- What Does The SAE Oil Number (Viscosity Grade) Mean?
- What SAE Oil Should I Use?
- 10 SAE Oil FAQs
- How Is SAE Different From Metric Measurement?
- Which Measurement Do Cars Use — Metric Or SAE?
- How Is SAE Different From API SN?
- What Is Oil Viscosity?
- What’s Engine Oil Thermal Breakdown?
- Is SAE Oil Synthetic?
- Is SAE The Same As Regular Oil?
- What Are Monograde Motor Oils?
- What Is ILSAC GF-6?
- What Are Motor Oil Types?
Let’s get started.
What Does SAE Stand For?
The SAE definition is the Society of Automotive Engineers, a United States organization founded in 1905 by Henry Ford and Andrew Ricker.
Now called SAE International, this group comprises engineers from automotive engineering, petroleum, trucking (SAE J1939), and aerospace industries.
In the automotive engineering space, SAE International issues the viscosity grading system for motor oil, standards for SAE tools, horsepower rating, etc.
Its primary purpose is to ensure consistency across markets. This means any SAE oil you bought in the US would be the same as one in Japan. If these standards weren’t in place, motor oil would vary everywhere, and prices would rise.
That brings us to what is an SAE motor oil.
What Is SAE Oil?
An SAE oil is a motor oil that complies with the standard laid down by the automotive engineers of SAE international.
Motor oils are classified by viscosity using a rating system — the SAE standard.
The letters “SAE” should precede the oil viscosity on the motor oil labeling. If it doesn’t, the oil might not comply with the SAE viscosity grade.
This means that if your engine manufacturer recommends “SAE 5W30 oil,” one labeled as just “5W30 oil” might not meet the viscosity characteristics of the recommended oil.
Now that you know the SAE definition for motor oil, let’s understand the SAE oil number.
What Is An SAE Oil Number?
The SAE number (also known as “viscosity rating” or “viscosity grade”) is a code to grade motor oils by their viscosity characteristics.
The SAE viscosity grade is not the actual viscosity value of the motor oil.
Originally, viscosity ratings were monograde — meaning it was only one number (like engine oil SAE 30). Multigrade oils were introduced in the 1950s to address varying engine operating conditions, such as driving in extremely low temperatures or high temperatures.
Use of engine oil additives to mineral oil, called viscosity index improvers (VII), allowed oils to thin at a slower rate, retaining a higher viscosity index even at a higher temperature.
So how does this help, exactly?
Remember that your engine heats up with use and may be influenced by high or low temperatures as seasons change.
Compared to mineral oil, multigrade oils can perform at a wider operating temperature range.
Engine oil grades like SAE 5W30 oil or 10W40 are commonly used (for diesel or gasoline engines) because they’re thin enough to flow at a low temperature (regions with colder temperatures) but thick enough to perform well at a higher temperature.
This means that your engine can generally use the same oil as summer switches to winter.
So how do you read the SAE oil number?
What Does The SAE Oil Number (Viscosity Grade) Mean?
Multigrade oils have two numbers, in the format “XW-XX.”
The SAE J300 standard defines these numbers individually for monograde oils.
Any multigrade oil must pass the SAE J300 viscosity grade standards to be approved for use.
So, these two numbers — what do they indicate?
A. The First Number And “W”
The first digit in the SAE size indicates how well the oil flows at 0oF. The letter “W” is for
“Winter.” The lower this number is, the less likely the motor oil will thicken at lower temperatures.
In cold temperature regions, 0W or 5W oils tend to work best.
B. The Second Number
This SAE size number indicates the oil viscosity rating at an operating temperature of 212oF. It shows how fast the motor oil thins and is crucial to proper engine lubrication and protection at a high temperature.
The higher this number is, the better the oil performs at increased ambient temperature.
If the engine heats up beyond a certain temperature threshold, the motor oil will experience a thermal breakdown and start to degrade.
Let’s see how these oil grades work for a clearer picture.
What SAE Oil Should I Use?
There’s a wide range of SAE oil available in the market. So, first, check what SAE size motor oil your engine manufacturer recommends.
SAE 5W30 oil is a very common engine oil for cars and light trucks.
But let’s say it isn’t available.
What do you do?
You’ll need to find oil based on your driving conditions. For example:
In low temperatures:
- An automotive engineer will suggest using SAE 0W-30 as 0W performs better in cold temperature situations than 5W. A matching 30 (second number) means it’ll still protect the engine at the expected operating temperatures.
- A lower “winter” rating can help deliver oil faster, quicken engine warm-up, and improve fuel economy (oil consumption) compared to a higher “W” rating.
In high temperature areas:
- You won’t have to worry too much about cold starts in a warm region. SAE 10W-30 or 10W-40 would work as the second number is the same or higher than required for operating conditions.
Note: The SAE has a separate viscosity rating system (SAE J306) for the axle, gear, and manual transmission oils. These shouldn’t be confused with engine oil viscosity grades. A high gear oil number (like 75W-140) doesn’t mean it has a higher viscosity than motor oil.
We’ve got the basics of SAE oil down.
Let’s go over some FAQs next.
10 SAE Oil FAQs
Here are the answers to some questions you might have:
1. How is SAE Different From Metric Measurement?
There are two technical standards for measurement — SAE and Metric.
The SAE standard is used for domestic vehicles, while the Metric measurement applies to foreign or non-domestic vehicles.
Both standards outline the standard head sizes for hex heads and the corresponding driver wrenches for them. But, SAE tools are measured in fractions/inches, while metric measurement ranges from 4 mm to 63 mm.
2. Which Measurement Do Cars Use — Metric Or SAE?
The measurement system used for the nuts and bolts depends on the country where the vehicle was manufactured. Most American-made vehicles follow the SAE tools system while other countries like Japan use metric measurement.
3. How Is SAE Different From API SN?
SAE stands for the Society of Automotive Engineers (United States). An oil rated as SAE Oil (for example, SAE 5W30) denotes its viscosity.
API stands for American Petroleum Institute. Engine oil with an API rating means that the lubricant meets the minimum performance standard accepted by auto manufacturers.
Ratings set by American Petroleum Institute are denoted by two letters with an S or C, where S indicates oil for gasoline engines and C for a diesel engine.
API SN and SP oils provide higher levels of performance than all other API “S” oils.
4. What Is Oil Viscosity?
Viscosity describes the resistance of a fluid to flow.
A higher viscosity (thicker) oil takes longer to flow than a lower viscosity (thinner) oil, and heat directly impacts engine oil viscosity.
5. What’s Engine Oil Thermal Breakdown?
Thermal breakdown can happen when the engine gets too hot and changes the oil’s viscosity.
The viscosity change will cause decreased oil flow, which may eventually lead to deposit buildup, damage to the engine’s metal surfaces, and increased oil consumption.
6. Is SAE Oil Synthetic?
SAE oils can be synthetic or otherwise.
Having the SAE designation simply means it complies with the SAE standard.
7. Is SAE The Same As Regular Oil?
An SAE oil can be regular oil (conventional oil) or other types of engine oil, like synthetic SAE (synthetic motor oil).
An SAE prefix means that the oil meets technical standards.
8. What Are Monograde Motor Oils?
Monograde oils only have 1 grade (like SAE 30 or 20W) as defined by the SAE J300 standard. They’re also called “straight-weight” oils.
The SAE J300 has 11 viscosity grades established, 6 of which are “winter” grades with the “W” suffix. An SAE J300 monograde oil can’t use polymeric viscosity index improver additives.
So, when is a monograde oil a better option than multi grade oil for a vehicle?
You might want to use a monograde oil for your vehicle in regions or seasons with extreme temperatures.
Say you drive in high temperature desert heat all the time; a monograde oil might make more sense than a multi grade oil to cope with a scorching ambient temperature.
9. What Is ILSAC GF-6?
Motor oil isn’t just a lubricant to reduce friction between moving parts, preventing engine wear (like corrosion or oxidation resulting in rust on critical parts). It also contributes to fuel economy, emissions controls, and engine design advancements.
The ILSAC GF-6 is the newest ILSAC motor oil standard, introduced in May 2020. It’s aimed at improved fuel economy and enhanced passenger car engine capabilities, providing low-speed pre-ignition (LSPI) and timing chain wear protection.
The GF-6 standard replaces ILSAC GF 5 and is backward compatible with previous generations.
10. What Are Motor Oil Types?
Engine lubricant can generally be divided into these four types:
- Conventional motor oil: Conventional oil is the purest form of oil derived from natural resources (mineral oil). Conventional motor oil is also the most common, cheapest, and easiest type to find.
- Synthetic motor oil: Fully synthetic oil is designed for better engine parts protection and performance (including improved fuel economy and enhanced engine life). Synthetic SAE is also the costliest.
- Synthetic blend motor oil: The synthetic blend has some of the benefits of full synthetic motor oil (like a corrosion inhibitor for oxidation resistance) but is mixed with conventional oil (mineral oil) to maintain lower costs.
- High-mileage motor oil: This is designed for older vehicles with typically more than 75000 miles on them. This synthetic oil contains special additives to prevent oil leaks and reduce oil consumption in older engines.
Using an SAE-graded and approved oil ensures that you’re putting something that meets industry standards in your engine. And you won’t have to worry about where you’re buying it or need company info to know who made the lubricant.
Just make sure that you’re using an oil with a suitable viscosity grade for your passenger car. It’ll help resist engine wear and extend your engine life.
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