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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 if your vehicle owners manual says to use, for example, a 5W-30. "W" means winter. 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. 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 the lubricant to flow through a fixed diameter orifice at a given temperature.

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

AMSOIL 0W-30 is 57.3 cST @ 40 deg. C, & 11.3 cST @ 100 deg. C

AMSOIL 5W-30 is 59.5 cST @ 40 deg. C, & 11.7 cST @ 100 deg. C

AMSOIL 10W-30 is 66.1 cST @ 40 deg. C, & 11.7 cST @ 100 deg. C.

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 0W-30 synthetic 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 ( as well as AMSOIL Series 2000 20W-50 Racing Oil). The extra horsepower and friction reduction from the 0W-30 often assists a race driver in attaining superior performance. In fact, we know 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.

We hope this brief discussion has answered your questions. If we have not sufficiently answered your questions or if you would like an additional explanation or recommendation for your specific application please email us using the link at the bottom of this page.

AMSOIL is the undisputed leader in synthetics.............

Since 1972, AMSOIL  Synthetics have proven to be the BEST.   AMSOIL also engineers and manufactures Ea Oil Filters with Nanofiber Technology which have a 25,000 mile/1-year service life as well as specialized filtration systems for commercial and fleet  applications in cars and light, medium and heavy trucks which can filter particles down to less than one micron (a standard full flow oil filter can only filter to 20-25 microns, and at a reduced efficiency) making oil changes virtually unnecessary and virtually eliminating engine wear.  These filters have been proven by millions of miles of over-the road trucks, construction equipment and fleet service.  

• AMSOIL saves you time and money.

• The only 25,000 mile/one- year and 35,000/one- year motor oil in the world.

• Exceeds the most stringent performance specifications of all major U.S. and foreign automotive and truck manufacturers.

• Provides up to two-times the wear protection of other motor oils.

• Increases the life of your vehicle.

• Improves performance, fuel economy and efficiency.

• Diesel oil and filtration products designed to deliver 1,000,000 miles for over-the-road trucks before engine overhaul.

• Used by many national racing teams, fleets, police departments, construction firms and trucking companies.

is comprised of a group of highly skilled team of Engineers and Lubrication and Filtration Specialists. You too, can join our group when you become an AMSOIL Dealer and take advantage of all that we offer as you use products in your own vehicles or begin your own AMSOIL business. You won't find a more knowledgeable and skilled group of Dealers anywhere which is very important when you need support as you build your business.

In addition, as a Dealer in our Group you will receive exclusive unlimited product, technical and business support from the only group of Truck and Automotive Engineers and Lubrication Specialists on the net. Dealers in our Group will also receive an exclusive business and internet promotional package. Please, email us at paulbetts@verizon.net for more details.

We do not only run our business on the internet. We also have numerous commercial, industrial, trucking, excavating, construction, logging, police, racing and many more accounts that we support and service on a regular basis. We have several fully stocked warehouses and fully equipped shop facilities. This provides us with excellent knowledge of the products, equipment and the business and the ability to respond immediately to any of your needs. We will use this knowledge and experience to help you get started so you too can achieve your goals.

We possess the skills, desire and knowledge to answer questions, solve problems, improve efficiency, reduce downtime, maintenance costs and increase the durability and life of all of your vehicles.

Read what our satisfied customers have to say about us. Read through our website. Contact us with any questions. If you decide to become an AMSOIL Dealer you will be joining, in our opinion, the most skilled AMSOIL group there is. We will help you get started and provide you with the tools and information in order to be successful in this business or with technical and product assistance to use AMSOIL products in your own vehicles.

We offer several options to receive information on AMSOIL. We welcome the opportunity to work with you personally as your servicing AMSOIL Dealer. Our AMSOIL Dealer Group is led by a Truck/Automotive Engineer and Lubrication Specialist with over 23 years experience. This exceptional benefit is unavailable elsewhere.

Please, email us at paulbetts@verizon.net and we will send you an exclusive comprehensive package of product, technical and business information. If you are serious about AMSOIL products and the business opportunity this is the best option. You will receive extensive technical and business support from both myself and my Direct Jobber, a Detroit, Michigan Truck/Automotive Engineer and Lubrication Specialist with over 23 years experience. We look forward to helping you learn about AMSOIL.

Or for a smaller, very general information package (which includes a catalog and Dealer application) you can request information via any of the links below.

To request a FREE Factory Direct Catalog

For Information on Becoming an AMSOIL Dealer

To Buy AMSOIL Products in the AMSOIL On-Line Store

Become a Preferred Customer- Purchase AMSOIL Products Factory Direct at Wholesale Prices- Save About 25-30%

To Sell AMSOIL in Your Store or Purchase For Use in Your Businesses Equipment

To visit the AMSOIL Corporate Website for Product and Business Opportunity Information

AMSOIL PowerSports Portal - We Put The Power in PowerSports

Diesel Power Site Forum for Power Stroke, Duramax and Dodge Cummins Turbodiesel

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