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.
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.
API Service Category for Gasoline Engines | ||
|---|---|---|
| Category | Description | Status |
| SN | The API SN category is an improvement over the API SM. API SN was introduced October 2010, designed to provide improved high temperature deposit protection for pistons, more stringent sludge control, and seal compatibility. API SN with Resource Conserving matches ILSAC GF-5 by combining API SN performance with improved fuel economy, turbocharger protection, emission control system compatibility, and protection of engines operating on ethanol-containing fuels up to E85. | Current |
| SM | For 2010 and older automotive engines. API SM was first introduced 30 November 2004 for gasoline engines. Category SM oils are designed to provide improved oxidation resistance, improved deposit protection, better wear protection, and better low-temperature performance over the life of the oil. Some SM oils may also meet the latest ILSAC specification and/or qualify as Energy Conserving. They may be used where API Service Category SJ and SL earlier categories are recommended. | Current |
| SL | For 2004 and older automotive engines. API SL was first introduced July 1, 2001 for gasoline engines. Oils meeting API SL requirements have been tested according to the American Chemistry Council (ACC) Product Approval Code of Practice and may utilize the API Base Oil Interchange and Viscosity Grade Engine Testing Guidelines. They may be used where API Service Category SJ and earlier categories are recommended. | Current |
| SJ | For 2001 and older gasoline engines. API SJ was first mandated in 1997. SJ spec oil can be used where API SH and earlier categories are recommended. | Current |
| SH | For 1996 and older engines. Valid when preceded by current C categories. | Obsolete |
| SG | For 1993 and older engines. | Obsolete |
| SF | For 1988 and older engines. | Obsolete |
| SE | For 1979 and older engines. | Obsolete |
| SD | For 1971 and older engines. | Obsolete |
| SC | For 1967 and older engines. | Obsolete |
| SB | For older engines. Use only when specifically recommended by the manufacturer. | Obsolete |
| SA | For older engines; no performance requirement. Use only when specifically recommended by the manufacturer. | Obsolete |
Reviewed by Sandyrun: 
I took my car in to get the oil changed. Recommended oil is 10w30. However Walmart used 5w 20. I was told it was ok there wouldn't be any damage to my engine. Is this true? I am still Scare to take the car on a long road trip.
| Mooresville, North Carolina Re: 2003 Bonneville SLE
If a much lower viscosity oil is used than recommended, it can lower the protection level especially, during high heat, load and stress. Replied by Tech Admin
Reviewed by Mark Pickard:
Preferred Customer
I am reaching out to get your input on changing which engine oil I use in my vehicles. With the expansion of the Signature Series line over the recent years I have revisited this and am considering a change. My apologies for the length of this inquiry, but I think it lends perspective by seeing my usage history.
I moved from Mobil 1 to Amsoil in 2005 and the selection was much different then than now.
2005 I started by using 10W-30 ATM and 5W-40 AFL for an older vehicle.
2006 Amsoil’s application guide at this time usually displayed the Series 2000 0W-30 as the top tier recommendation. I began using the 0W-30 TSO and 10W-40 AMO.
2007 Continued same products.
2008 The Series 2000 0W-30 TSO evolved to Signature Series SSO. No other changes.
2009 Added 5W-30 ASL for son’s Subaru and no other changes.
2010 No changes.
2011 0W-30 Signature Series evolves to AZO as the SS line expands. No other changes.
2012 No new changes.
2013 I contacted Amsoil Technical Services asking if using the 0W-30 AZO for all my current cars was reasonable. At this point all cars I owned or serviced called for 5W-30 and 10W-30 as preferred. I got an affirmative response so I was using only 0W-30 AZO.
2017 I added the use of the reformulated 5W-30 XL (XLF) for servicing my daughter’s vehicles to help her budget and my brother-in-law decided to make that switch also for his car.
2018 Recently I was reviewing the Signature Series Technical Properties data comparing figures from 2012, 2016 with the latest September 2017 data. I noticed that from 2016 figures to 2017 figures that the NOACK Volatility the numbers had gone down for all viscosities except the 0W-30 AZO which went from 8.4 to 8.8. Considering that in the Seattle area our winters rarely get below 20 degrees F and the summers rarely exceed 90 degrees F that maybe my best Signature Series product would be the 10W-30 ATM. My personal vehicles all designate 10W-30 as my preferred viscosity. Those are:
1986 Dodge Caravan SE 2.6
1991 Toyota Deluxe Pickup 2.4
1991 Mazda Miata 1.8
2006 Volvo V70R
Am I overlooking anything in this data that I should be considering? I would describe my driving style as spirited at times. Would changing to the 10W-30 ATM now be my best choice especially when I venture into the higher RPMs? I have had trouble free performance from the AZO, but I am always looking for the best suited product as things always evolve in the product line.
Devoted Amsoil consumer. Thanks.
| Everett, Washington Re: Should I Change My Product Selection?
Hi Mark,
Thank you for the detailed comment and for being an AMSOIL customer.
As mentioned in this article, both 0W30 and 10W30 are 30 weight oils and either one can be used.
0W is preferred by OEM for newer vehicles to achieve better fuel economy by reducing internal drag.
Theoretically 10W withstands shear at higher operating temperatures better than 0W.
Since 10W30 is recommended for your vehicles, you could use AMSOIL SS 10W30 and benefit from slightly increased engine protection. Replied by Tech Admin
Reviewed by Mark:
My owners manual for this Volvo penta boat engine suggests 30 weight synthetic, would 10w30 synthetic also work?
| Lake Stevens, Washington Re: synthetic 30 weight
Yes, you can use AMSOIL 10w30 synthetic oil. AMSOIL 10w30 provides excellent cold and hot temperature performance from its robust full synthetic base oils.
However, if your are operating in extreme cold temperatures, use 5w30 or 0w30 to get better cold flow advantage. Replied by Tech Admin
Reviewed by Jaytan:
I have used nothing but Amsoil products in all my vehicles - all the best synthetics when available.
A few of my vehicles call for a 5W-30, one calls for a 5W-20.
I have been using 0W-20 because I like the Colder Weather oils for Canada and I'm an easy Senior driver.
My twin turbo 3.5 liter Ecoboost has cost me one turbo already at 70,000 Kms (45,000. miles).
Would you recommend using the 0W-30 or 5W-30 or 5W-20 for the sake of the Turbochargers ?
I'd sure appreciate a reply.
Kind regards,
Jaytan
| Westbank, British Columbia Re: Weights of Amsoil applications
Sorry to hear about turbo failure. 5W30 is the recommended viscosity for the EcoBoost. Use the signature series for maximum protection.
You can also use 0w30 as it is technically a 30 weight oil. However for warranty purposes, it is best to stick with OEM recommended 5w30. Replied by Tech Admin
Reviewed by Tomahawk :
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?
| Garwood, New Jersey Re: High Mileage
You can use 5w30 or 10w30 signature series oil. Replied by Tech Admin
Reviewed by dark:
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
| 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
Reviewed by Kevin:
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.
| 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
Reviewed by bill:
Different oil
| 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
Reviewed by Rensquires:
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.
| 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
Reviewed by Ron:
Type of oil to use
I currently have a 1990 ZR-1 Vette, with a LT 5 engine which has flat valve lifters and require more Phosphorus and Zinc then most engines. IN Canada this oil is $ 15.00 a quart. since car requires 9 quarts very expensive. Is there another brand with similar contents as Amsoil 10w/30 Z / Rod that can be used ? Thanks