Which 30 Weight Oil Do I Use, 0W-30, 5W-30 or 10W-30?

We get asked this question so often that we have included this special page dedicated exclusively to answering the question.

AMSOIL 0W-30, 5W-30 and 10W-30 synthetic motor oils are ALL 30 weight oils. The answer is that ANY one can be used regardless of the vehicle owners manual recommendation. To better understand, in a 5W-30 oil, the "W" stands for winter performance. In winter weather the 0W oil will flow like a 0W oil, and the 5W will flow like a 5W oil and a 10W will flow like a 10W oil just until the engine warms up. This multi-grade performance allows faster oil flow during cold start, however when the oil warms up, they all reach the designated 30 weight viscosity.

In order to understand the differences one has to first understand that the numerical values given to these various weight oils are strictly empirical numbers. For example, 0W does not mean that the oil has no weight. That is one of the reasons why we say it is strictly an empirical number.

In order to determine the differences between the three oils one has to look at the kinematic viscosity of each lubricant. The kinematic viscosity is essentially the amount of time, in centistokes, that it takes for a specified volume of lubricant to flow through a fixed diameter orifice at a given temperature.

Let's compare the kinematic viscosity of the three AMSOIL lubricants

As you can see from the data above the kinematic viscosities are extremely close. Therefore, whether you use the 0W-30, 5W-30 or the 10W-30 is strictly a matter of choice. With the small differences in kinematic viscosity you would be hard-pressed to detect these differences on initial engine start-up without specialized engine test equipment.

All three oils are excellent motor oils and ANY one can be used in a vehicle which requires either a 0W-30, 5W-30 or 10W-30 oil as well as in several other engine applications including an engine which recommends a 5W- 20 oil.

AMSOIL Signature Series 0W30 100% Synthetic Motor Oil (SSO) Severe Service motor oil is one of the best synthetic lubricants AMSOIL manufacturers for gasoline engine passenger vehicles and light trucks. The molecular and chemical technology used to develop this oil was derived from AMSOIL's Racing Oil. It is a 35,000 mile/1-year motor oil. This is the same oil used by numerous police vehicles and severe duty fleets nationwide. In fact, many national racing teams use the 0W-30 for the qualifying event, then they change to the AMSOIL 20W-50 Racing Oil for the race. The extra horsepower and friction reduction from the 0W-30 often assists a race driver in attaining a better starting position. In fact, we know exactly which race teams use it, but cannot disclose that information.

This leads to the next topic: many people also ask us if the 0W-30 is too thin a viscosity oil for high ambient temperature operation. The answer is absolutely not! Thicker viscosity oils are not always necessarily better since in addition to its' various engine lubrication functions, an oil must also effectively transfer heat. Only about 60% of an engines cooling is performed by the engine coolant, and only on the upper half of the engine. The remaining 40% of an engines cooling is performed mainly by the engine oil.

Although a vehicle that is recommended to use a 30 weight oil can also use a 40 weight oil, it is usually not needed. You will gain absolutely no benefit from using a thicker viscosity oil if it is not needed. The only time we recommend a 40 weight oil, such as AMSOIL's 10W-40, to a customer in a passenger car or light truck application is if the vehicle's engine is excessively worn and consumes oil at a higher than normal rate or if the vehicle is being used for very severe duty, high load, high temperature applications.

Click here to see the TYPICAL PACKAGE that most people use for oil in their cars for their daily drivers when they switch to Amsoil for the first time.

When you look at the different Amsoil products, you'll see category descriptions next to them. (Look to the right of the 10W40 bottle in this example and you will see a list starting out with the letters API.) This will help you determine which oil is compatible with your engine.

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Blog Title: Which 30 Weight Oil Do I Use, 0W-30, 5W-30 or 10W-30?
Current Rating: 4.51 out of 5 stars
Votes & Reviews: 36 vote(s) and 5 user reviews.

Comments (5)

Reviewed by Tomahawk :

High Mileage

I have a 98 3.8l firebird but with 130,000 miles in Florida. Do I say with factory spec 5w30 or is there something better?

Item Reviewed: Which 30 Weight Oil Do I Use, 0W-30, 5W-30 or 10W-30?

July 28th, 2017 | Garwood, New Jersey

Re: High Mileage

You can use 5w30 or 10w30 signature series oil. Replied by Tech Admin

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Reviewed by dark:

oil to use

My 2017 3.5 V6 Tacoma says to use 0w20. I have 5w30 left from my previous Tacoma 4.0 V6,can I use these jugs up before going to the recommended 0w20

Item Reviewed: Which 30 Weight Oil Do I Use, 0W-30, 5W-30 or 10W-30?

January 1st, 2017 | Shawnigan Lake, British Columbia

Re: oil to use

5w30 will not cause engine damage, however, it might slightly lower fuel economy as it is 50% higher viscosity compared to 0w20.

Also warranty issues can arise if the OEM recommendation is not followed. Replied by Tech Admin

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Reviewed by Kevin:

Please add low temp data

Thanks for this excellent reference. The only thing missing is kinematic viscosity at very low temps. This is very relevant for cold winter starts for us here in Canada. So could you please add kinematic viscosity data at say, -30c, -20C, 0C?

From what I've read, there may be a large difference between 0W and 5W at very low temps. My manufacturer recommends 5W30 for my car and climate, but I'd be inclined to use 0W30 synthetic here in Canada, especially if the data supports it.

Item Reviewed: Which 30 Weight Oil Do I Use, 0W-30, 5W-30 or 10W-30?

September 30th, 2016 | Calgary, Alberta

Re: Please add low temp data

Pour Point data can provide the difference in cold temperature behaviour when compare between viscosities. AMSOIL 5W30 has a pour point of -51c (-60f). AMSOIL 0W30 also has a pour point of -51c (-60f).

However, another brands 5W30 can have a pour point of less than -15c. Therefore, cold weather performance is not entirely based on the viscosity but the quality of base oils.

Base oils containing paraffins, waxes and other impurities will perform poorly compared to high end oils such as AMSOIL signature series. Replied by Tech Admin

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Reviewed by bill:

Will 5w30 hurt my 87 305

Different oil

Item Reviewed: Which 30 Weight Oil Do I Use, 0W-30, 5W-30 or 10W-30?

February 16th, 2016 | Tusket, Nova Scotia

Re: Will 5w30 hurt my 87 305

Hi Bill, you can certainly use AMSOIL 5w30 in your Chevy 305. However, AMSOIL 10W-40 Synthetic Premium Protection Motor Oil (AMO) is the best oil for this motor. Replied by Tech Admin

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Reviewed by Rensquires:

engine shortening oil

my Polaris ranger 800 xp is shortening oil. It uses PS4 oil. Is this equivalent to 5w 50 oil?
I have only 2000 miles on it.

Item Reviewed: Which 30 Weight Oil Do I Use, 0W-30, 5W-30 or 10W-30?

October 22nd, 2015 | Mount Pearl, Newfoundland

Re: engine shortening oil

Hi,
Increased oil consumption indicates internal wear including but not limited to piston, rings, valves etc.

You can stop the progression of this by reducing internal wear by using higher quality full synthetic oil such as AMSOIL 5W-50 Synthetic ATV/UTV Motor Oil.

From above search box type AUV50 for more information on this ATV/UTV Motor Oil

Let us know if you should have any questions. Replied by Tech Admin

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