You may have heard of (and are likely using) SAE 5W-30 or SAE 10W-30 motor oil.
These are engine oil viscosity grades designed by the SAE (Society of Automotive Engineers), which is why you see “SAE” appended before the grade.
But what about SAE 30 oil?
Is SAE 30 oil the same as 5W-30 and 10W-30 oil?
Don’t worry.
We’ll take a closer look at what SAE 30 motor oil is, what it’s used for, and answer some questions on this oil.
Let’s get started.
The SAE 30 oil is a single grade oil with a viscosity rating of 30.
It’s called a single grade (or monograde) oil because it only has one viscosity grade. This is different from a multi grade oil, like 10W-30, which is rated for both SAE 10W and SAE 30.
A single grade oil can be rated for a hot viscosity grade or a cold-start viscosity grade (where it’ll have a “W” suffix, standing for Winter). In a multi grade oil, the winter grade viscosity emulates the engine crank at cold temperatures.
The SAE 30 oil is rated only for hot viscosity.
This rating indicates how viscous the motor oil is at an operating temperature of 100OC (212OF).
Why is this important?
Temperature has a direct impact on viscosity.
If an engine heats up beyond certain temperature thresholds, the motor oil will experience thermal breakdown and start to degrade. You’d want to avoid this as sufficient engine lubrication is key to ensuring long engine life.
Next, let’s see where you’d use SAE 30 motor oil.
The SAE 30 motor oil is typically used in small engines like a small tractor, snow blower, or lawn mower.
And while most modern engines in passenger vehicles today use the multi grade oil variety, you’ll still find some four-stroke gasoline engines (like those in powerboats, motorcycles, or older cars) calling for SAE 30.
Now that we know more of the SAE 30 oil, let’s move on to some FAQs.
Here’s a collection of SAE 30 oil FAQs and their answers:
Viscosity measures the flow rate of a fluid at a particular temperature.
The Society of Automotive Engineers defines engine oil viscosity ratings from 0 to 60 in the SAE J300 standard. A lower grade generally indicates a thinner oil, and a higher rating is for thicker oil. Winter grades have a “W” appended to the number.
The SAE and ISO (International Standards Organization) use different scales to measure viscosity.
For comparison:
Note: ISO VG is short for International Standards Organization Viscosity Grade.
SAE viscosity grades cover engine crankcase and gear oils.
ISO grades are comparable to the SAE, and include others like the AGMA (American Gear Manufacturers Association) grades for gear oils.
SAE 40 oil is a slightly thicker oil than SAE 30 and will thin out slower at high temperatures.
No.
Unlike SAE 30, SAE 10W-30 is multi grade oil. SAE 10W-30 has SAE 10W viscosity at a lower temperature and SAE 30 viscosity at a hotter operating temp.
There is no SAE 30W (which is a cold temperature grade) in the SAE J300 standard.
Only SAE 30 is available, which refers to a hot viscosity rating at 100OC.
SAE 30 is typically a non detergent motor oil used in small engines.
Detergent oils contain special additives designed to trap and suspend dirt and dissolve engine oil sludge in the oil until it’s changed. A non detergent oil doesn’t have these additives.
A non detergent motor oil will usually be marked as such. So, any motor oil that isn’t marked as non detergent is a detergent blend by default.
SAE 30 motor oil and SAE 30 marine engine oil are different things.
Though oil in a four-stroke marine engine does the same thing as in an automobile engine, marine and passenger vehicle motor oils aren’t interchangeable.
Marine engines are often cooled by lake, sea, or river water. So, while they’re controlled thermostatically, their temperature cycling is different from a road-going automobile.
Marine engine oil needs to handle high RPMs and the constant load experienced by marine engines. They require a corrosion inhibitor that can better resist moisture and rust compared to automotive engine oil.
These oils also often go past their oil change window, so antioxidants are critical to extending oil life and providing a long engine life.
SAE 30 motor oil can be synthetic oil or otherwise.
Here’s the difference:
Synthetic oil is an oil type, while SAE 30 is an oil grade.
Both oils have a “30” hot viscosity rating.
This means SAE 5W-30 oil has the same flow rate as SAE 30 at operating temp. So, technically it’s fine to use SAE 5W-30 oil in place of SAE 30.
SAE 30 motor oil is specified for use in some older 2-stroke and 4-stroke diesel engines.
Before using the SAE 30 oil, make sure to check which Diesel Engine industry classification is needed — like API CK-4 or API CF-4. This should be indicated on the oil bottle.
Note: API (American Petroleum Institute) “S” classifications are for gasoline engines (not diesel engines) like API SN or SP.
API requires all engine oil to be compatible with each other. This means you can mix any SAE graded motor oils.
You might see SAE 30 oil specified for an older engine, like those in classic cars. However, modern engines typically require multi-grade oils, so using an SAE 30 motor oil in any vehicle built recently would be inadvisable. Always check the owner’s manual first!
SAE 30 oil is the most common oil for small engines. It’s often recommended for lawn mower engine use. To be sure, always check the lawn mower owner’s manual first.
Yes.
Many engine oils, including SAE 30 oils, have additives to improve engine performance and enhance engine protection and lubrication.
A single grade oil like SAE 30, however, cannot use polymeric viscosity index improvers.
