A reader asks: I’m using 100% biodiesel derived from used vegetable oil in my van’s diesel engine. I’m told that I have to change the engine oil more often when using biofuel. Why is this?

Our answer: There are several reasons as to why oil change intervals must be reduced when replacing diesel fuel with biodiesel.

Lower Fuel Energy And Deposit Formation

The main concern with biodiesel is that it provides reduced fuel quality. The simple fact is that biodiesel delivers less energy than regular diesel fuel. This means that combustion is less complete than with regular diesel. This brings a greater tendency toward fuel dilution in the motor oil and an increased incidence of engine deposit formation.

Vegetable-based fuels also have a higher tendency to form deposits on fuel injectors. Fouled injector spray patterns can lead to increased fuel dilution in the motor oil.

Biodiesel Oxidization And Moisture Attraction

There is also a very high potential for increased engine deposits when biodiesel has oxidized. The quality of biodiesel processing and storage practices is absolutely paramount. Incomplete processing and bad storage practices can lead to a myriad of problems. Oxidized fuel can contribute to poor combustion, reduced fuel economy, engine deposits, corrosion, fouled fuel injectors and reduced starting performance.

Biodiesel attracts moisture which can lead to corrosion and reduced performance. This is another reason to use the best possible storage practices.

All of these factors can contribute to faster degradation of engine oil in bio-fuel-powered vehicles.

How To Determine An Oil Change Interval When Using Biodiesel

With all of the variables at play, it is very difficult to determine an oil change interval. Oil analysis is a cost-effective way to determine when to change oil. One could be changing oil too late or too early. Oil analysis can offer a snapshot of the condition of the engine and the motor oil. Analysis shows whether items such as as wear metals, fuel dilution, moisture and coolant are elevated to dangerous levels.

Advantages Of Using Biodiesel

There are advantages to using biodiesel. Some studies suggest that biodiesel can offer improved engine wear control. Biodiesel has excellent lubricating properties which can extend the life of fuel pumps and injectors. Lastly, pure biodiesel offers very clean emissions compared to regular diesel exhaust.

New AMSOIL OE 0W-16 Synthetic Motor OilAMSOIL’s new OE 0W-16 Synthetic Motor Oil is now available for sale. This brand-new viscosity is offered in the value-priced OE Series to start. We suspect that as the 0W-16 grade becomes more prevalent, it will eventually be offered in AMSOIL’s premium XL and Signature Series lines.

Where Can I Buy 0W-16 Engine Oil?

Oildepot can ship this AMSOIL Synthetic 0W-16 to your door from warehouses in Canada and the United States. We have wholesale programs for personal-use as well as for dealers and shops. Contact us for a wholesale price list using the form on this page.

Why Did AMSOIL Come Out With A 0W-16?

The 2018-19 Honda Fit and the 2018-19 Toyota Camry (2.5L conventional and hybrid engines) recommend the use of 0W-16 motor oil. Automakers are scrounging for every conceivable way to improve fuel economy. Make no mistake, that is why this new ultra-thin motor oil viscosity is on the market. Expect automakers to spec 0W-16 for more models in the very near future.

Will 0W-16 Be Too Thin?

We discuss this question in our post “Is 0W-16 Motor Oil Too Thin?“. We believe that engine design and motor oil chemistry have reached the point where 0W-16 is very viable. Extensive testing goes into industry motor oil specifications and engine technology. We are confident that the homework on 0W-16 is complete. You can bet your last dollar that AMSOIL OE 0W-16 was rigorously tested. It will provide the heavy-duty synthetic wear protection that AMSOIL is famous for.

Remember that many motorists had grave concerns when the 5W-20 motor oil grade was introduced almost two decades ago. Now, the majority of modern passenger cars and light-trucks use 5W-20 or 0W-20. After hundreds of millions of miles of use, 20-weight motor oil has been proven to offer excellent wear protection.

We predict that the 0W-16 motor oil grade will eventually deliver the same successful track record.

Do you have questions about 0W-16 motor oil? Contact us using the form on this page or call us at 1-800-748-5781.

Canadian AMSOIL customers ordering at full suggested retail prices now get free shipping on orders over $130. For orders under $130, a flat shipping rate of $11.99 will be charged. Now all AMSOIL account types have a free shipping option. Remote areas may not be eligible for free shipping. Contact us with your postal code and we can determine this.

What Is An AMSOIL Catalog Customer?

Orders placed at full suggested retail are also called “catalog orders”. US catalog orders received a free shipping option earlier this year. Why would a customer want to order at full suggested retail? For very small orders (such as just a few bottles), a wholesale account may not make sense.

Here is the complete list of AMSOIL Account Types and Free Shipping Options in Canada and US.

How to Place AMSOIL Orders

  • The first step is to request a wholesale price list using the form on this page. You may be surprised to find that an AMSOIL wholesale account is feasible even for relatively small orders.
  • Once you have a wholesale account, orders can be placed online or by telephone.
  • If your order is just a few quarts, an order at full suggested retail would be an option.
  • Here are ordering options.

AMSOIL Account Types


AMSOIL dealers can re-sell and market the products. Dealers can earn a commission as well as the retail mark-up profit.

Preferred Customers

This wholesale option is for individuals using AMSOIL products for their personal use. This is AMSOIL’s most popular wholesale program.

Retailer Account

Retailer wholesale accounts can be any type of storefront business that installs or re-sells AMSOIL products. Parts stores, oil change shops or power sports dealers are examples.


Commercial wholesale accounts are business enterprises with fleets or equipment. This type of account uses the products for company-use and does not re-sell. Examples include farm, construction, plumbing, electrician, trucking and much more.

Catalog Customer

A catalog customer is simply an AMSOIL customer that buys the products at full suggested retail prices. These tend to be customers that place very small orders. Anyone wishing to buy AMSOIL with orders approaching a case lot should consider a Preferred Customer membership. Again, contact us with using the form on this page for more details.

Questions? Contact us using the form on this page or call us at 1-800-748-5781.