Selecting The Right Oil For Your E85-Powered Application

E85 has become a popular fuel for high-performance applications, especially those who use a forced induction combination. There are numerous advantages to running E85, but you also need to keep in mind that the fuel can be hard on your engine’s oil. We talked with Driven Racing Oil to learn why it’s important to use an engine oil that is engineered to work with E85 applications.

There are some big performance advantages to running E85. The fuel is more affordable than traditional race gas, it has an octane rating of 100 to 105, and it produces lower inlet air temperatures as the air enters the cylinder. You can even find it at many pumps across the United States. It’s also available in designer blends that have special additives.

It doesn't matter if you're running E85 from the pump, or an exotic 85 made for racing, the oil you select needs to have the right stuff inside to keep your engine safe.

What E85 Can Do To Engine Oil

E85 is an alcohol-based fuel that’s harder on engine oil because it will dilute the oil and can cause corrosion inside the engine.

Alex So from Driven Racing Oil explains how alcohol-based fuels like E85 can dilute your engine oil.

“Alcohol-based fuels dilute oil because of the increased fuel volume required versus gasoline. The viscosity of the oil will decrease once the oil is diluted which compromises the wear protection of the oil. Special consideration for engine oil selection is critical when using E-85, as fuel dilution can wash down cylinder walls, affecting the ring seal. This can cause a power reduction and increased wear. Engine oils that have a more polar base oil do a better job of attaching to the cylinder walls and resisting washout. Keep in mind, fuel dilution can be significantly increased when running boost with E85.”

It doesn’t matter what type of engine or power adder you’re using, a high-quality oil will go a long with when running E85 as your fuel of choice.

Engines that run on E85 require a lot more fuel than ones that run on regular gasoline. When you’re running E85 you’re introducing more fuel into the engine. A boosted E85 application is going to require even more fuel since you’re adding a larger volume of air.

 All of that additional fuel is going to lead to an oil dilution issue. Lake Speed, Jr. explains why E85 will dilute your engine’s oil and the problems it will cause.

“When, you have a higher level of fuel dilution, you will have a higher level of wear primarily because the fuel is diluting the oil. The viscosity of the oil is the most important characteristic of the lubricant. As viscosity decreases, wear increases because your oil films are getting thinner. So, when you think about the boosted E85 scenario, that increased volume of fuel is physically washing the oil away.

The corrosion that E85 can cause is created by the byproducts that come from the combustion process. These byproducts move through the engine and eventually set up shop in the oil. When these byproducts chemically react with the moisture, it can cause corrosive contamination. The corrosive compounds will then start to attack parts inside your engine including the bearings.

“It’s important to use the proper viscosity designed to work with alcohol-based fuels because high fuel dilution will lower the oil’s viscosity. High fuel dilution can change the oil’s viscosity from 20w-50 to 10w-30, thus reducing the wear protection. So, in high-performance engines, you want all the protection you can get while turning high-RPM and not compromising the oil’s wear protection. Typically for this point — when we have excessive fuel dilution — we usually recommend going up one viscosity grade,” So says.

E85 Friendly Oil Characteristics

There’s an astounding amount of different engine oil available today. You can easily get lost in the sauce trying to figure out what the differences are between all these lubricants. One thing that So did point out is that there is no difference in formulation for alcohol and gasoline-based fuels.  He says that it’s recommended to use a higher viscosity of engine oil for E85 applications. The thicker oil will help deal with the fuel dilution issues that E85 can create.

The additives in the oil and the viscosity are what you need to pay attention to in an E85 application.

You can fight oil dilution by changing the weight of the oil you use. Speed adds his thoughts on why it’s important to go up in viscosity in an E85 application.

“The first strategy is to increase the viscosity of the oil to compensate for the dilution, knowing that you’re not going to stop or prevent it. So, what you need to do is increase the viscosity of the oil so that you have an offset. For example, say you start off with  5W30 oil. Once you add all that fuel, now it’s down to a 5W20 viscosity oil. This will cause wear on everything in the engine to increase. But, if I start with 5W40, then the E85 dilutes it a little bit, and then I’m back at my desired 5W30 oil.”

Typically, you’ll want to talk with your engine builder about what weight oil you should run in your powerplant. All In Racing Engines built our mill, and the owner Jimmy Bowling suggested we use 20W-50 based on how he set the bearing clearances, and since it was a forced induction engine. Bowling also recommended we use Driven Racing Oil products since that’s what his shop steers customers towards.

Driven's GP-1 20W-50 is what our engine builder recommended for our boosted build that feeds on E85.

We contacted the team at Driven Racing Oil and told them what our engine combo was along with the fuel we’d be using. Driven’s recommendation was to use its GP-1 20W-50 oil.

“GP-1 helps high-performance engines being that it is a synthetic-blend performance oil designed to increase power and decrease wear. What makes GP-1 special is that it is formulated with a unique cut of Pennsylvania-grade base oil, then blended with synthetic components and performance additives.  The Pennsylvania-grade base oil provides the excellent film strength that oils from the region are known for. Having quality base oil and film strength is critical for engine wear protection, especially when using a flat tappet cam or alcohol fuels,” So explains.

Not all oil is created equal and you’ll want to keep that in mind when you’re selecting what goes in your engine. Any off-the-shelf oil might be okay for your lawn mower, but you’ll want something with the right additives for your E85-slurping engine. By making sure you’ve selected the right oil, your engine will remain happy and healthy for many miles.

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Brian Wagner

Spending his childhood at different race tracks around Ohio with his family’s 1967 Nova, Brian developed a true love for drag racing. Brian enjoys anything loud, fast, and fun.
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