Under The Influence: Alcohol’s Effect On Your Engine Oil

Engine oil selection is a very important subject, which often generates strong opinions. I think it’s safe to say that we’ve all seen that those opinions can be based on emotion just as much as technical knowledge. Think about when you got your first car, and that member of your family told you to only ever use “Brand X” oil and your car will last forever. No real scientific data as to why that oil was better, just that somewhere along his or her life experience timeline, that brand was imprinted on them as being the best.

Thankfully, we live in a day and age where data is widely available and verifiable, not to mention the variety of options available to the consumer. To that end, we decided to take a look at what used to be a quite rare situation, but has become far more common as of late: selecting an oil for use with alcohol as fuel, and the resulting special concerns you’re faced with.

Our in-house BlownZ06 race team has extensive experience with using methanol as a fuel, and thanks to Driven Racing Oil, the oiling needs in that application have been met. We asked Lake Speed, Jr. of Driven Racing Oil about the the special requirements for engine oil when used with alcohol. As it turns out, the concerns aren’t confined only to high-end methanol-fueled race engines, thanks to the popularity of E85 and water/methanol injection in even mild performance applications these days.

BlownZ06 has used Driven Racing Oil since day one, and prior to that, BlownZ did as well. The team sticks to a rigid oil change schedule between the stresses of drag racing and the methanol fuel’s contamination of the oil.

A Better Life Through Chemistry

“High detergent oils (think diesel oils and passenger car oils) hold more fuel in the oil, which lowers the viscosity of the oil. Fuel is a bad lubricant, so you don’t want the oil and fuel mixing together,” explains Speed. “When oil and fuel mix, it can turn white in color. That is commonly called ‘milking up’ and different oils handle the methanol differently. At the end of the day, you want fuel to be fuel and oil to be oil. A mix of fuel and oil is only good in a two-stroke.”

“Milking of the oil can be a problem even in street cars running water/methanol injection,” says Speed. “The best oil for these applications is something that doesn’t hold the fuel and water in suspension.” To that end, we refer back to the workflow that Driven has been preaching for as long as we can remember.

Here is a photo of three different oils mixed with the same amount of methanol. As you can see, different oils handle the methanol differently. You can also see why it’s called “milking” of the oil, which is different from blowing a headgasket and creating a “milkshake.”

“You should always choose an oil by starting with the application first. The application will always dictate the correct chemistry, and then you choose a brand you trust to deliver that chemistry consistently,” Speed explains. “With that said, methanol injection engines require chemistry tailored to handle the extra fuel dilution that comes along with injected methanol, so the owners of these engines should be looking for oils that are designed for methanol fuels.”

Putting Theory Into Practice

As an example, let’s look at BlownZ06 and its use of Driven XP6 oil. “We recommended XP6 (15W-50) because the engine runs on Methanol instead of race gas. When the engine [of the BlownZ Camaro, the team’s previous racecar] was running race gas, the team ran XP9, which is a 10W-40,” Speed says. “The chemistry of XP6 and XP9 are the same. The only difference is the viscosity. Because methanol requires a richer air/fuel ratio, there is more fuel dilution of the oil, especially in the cylinder bores, so going to a thicker oil offsets the increased fuel dilution. When switching from gas to Methanol or E85, it is recommended to go up one viscosity grade to compensate for fuel dilution. In the BlownZ06 application, that meant going from 10W-40 to 15W-50.”

At the risk of muddying the waters (no pun intended) we asked Speed to expand on the viscosity required for alcohol engines. “Outside of the fuel choice, the bearing clearances and operating temperature are what dictates the correct viscosity,” Speed relates.

“This may sound strange, but the the 0W-5 oil that the Pro Stock guys use is actually thicker in the engine than the 5W-30 that most people use in their street LS engines. That is because the Pro Stock engines run very low oil temperatures. The oil temp in a Pro Stock engine might be 100°F at the end of quarter-mile pass, and at 100°F, that 0W-5 oil has the same viscosity as a 10W-40 does at 220°F. However, viscosity, temperatures and bearing clearances are a subject for another day.”

Both XP9 and XP6 are formulated to work with methanol fuel. When the BlownZ team switched from race gas to methanol, since the chemistry was already correct for alcohol, the only change needed in oil was to increase a step from the viscosity of the XP9 to the thicker XP6 formulation.

Another factor to consider when using an alcohol-based fuel, is that your oil change interval will change. For example, the BlownZ06 crew changes the oil after every race weekend. “Because drag racing is short bursts of high power, the oil never gets hot enough to evaporate out the fuel and water that gets into the oil,” Speed says. “As a result, the oil must be changed to remove these contaminants. Endurance racers like NASCAR, run the engines at high temperatures (sometimes approaching 300°F), so all of the fuel and moisture are boiled out of the oil. As such, the oil can live for many more miles in endurance racing applications compared to drag racing. Simply put, the oil does not break down, it just gets contaminated, so it has to be changed.”

Before you start to fret, as Speed pointed out, the oil isn’t degraded, just contaminated. You don’t throw your clothes away when they get dirty, right? Some drag racers choose to decontaminate and reuse their oil more than once. “Back to endurance racing for a second, in long races the oil gets hot enough to evaporate out the fuel and moisture,” Speed explains. “Since that doesn’t happen in drag racing, you can still evaporate out the moisture by putting the oil in a crock pot and heating it up. I know it sounds redneck, but it works!”

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About the author

Greg Acosta

Greg has spent over a decade in automotive publishing as Senior Editor of Race Pages magazine. In his free time, he is a firearms instructor and volunteer in the police armory.
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