2500 Mile Oil Changes Because You’re Running E-85? P-shaw
Last week a Toyota dealership dropped a link on Twitter with the warning “Did you know you have to change your oil twice as often if you’re running E85?” (or something like that ).
The link went to a page that advocated a 2,500 mile oil change frequency for truck owners using E85. Of course, there was no explanation as to why E85 users needed to change their oil twice as often, just that they should. THAT, ladies and gentleman, is why dealership service departments get a bad wrap. Instead of explaining why 2,500 might be a prudent choice (and it might), they make a blanket statement. I say p-shaw. This recommendation is, at best, paranoid.
First, here’s why this recommendation was made. We all know that E85, when compared to “normal” gasoline (which is about 10% ethanol), is fairly acidic. This acid has the ability to neutralize some of the lubricating ability of normal engine oil, but only mildly so. In fact, I would guess that regular old motor oil would breakdown more from heating and cooling over the course of 5,000 miles than it ever would from the acid inherent in E85. Normal E85 isn’t much of a threat to engine oil – the issue occurs when normal E85 becomes contaminated with water.
The combustion process of water-contaminated E85 will lead to the formation of a strong acid (formic acid, to be exact). This acid, left unchecked, has the ability to cripple an engine because it can 1) dramatically reduce the lubricating ability of normal motor oil and 2) eat away at the high-tolerance metal engine components. E85 with water contamination, in a normal engine, is dangerous stuff. Changing the oil frequently is a good insurance policy for a normal engine running E85, and this is probably the basis of this recommendation.
HOWEVER, if you’re running E85, you’re probably not driving a normal engine! Vehicles that are factory capable of running E85 have specially coated pistons and valves that are less susceptible to acid wear. Unless you’ve installed an E85 conversion kit on a “normal” gas motor, you’ve got some built-in protection. Moreover, if you’re driving your factory flex-fuel vehicle with E85 and you’re using the factory recommended E85 oil blend, your oil has an extra dose of detergents that designed to neutralize any acid that might form.
Finally, and perhaps most importantly, water contamination in E85 is pretty darn rare. Keep in mind that water contamination levels of 1% or less do not cause a significant problem, and anything above 1% is readily preventable. Between tank storage regulations and testing equipment and frequent fuel testing (check out the state of Minnesota’s E85 water contamination procedures for an example), finding E85 with any significant water contamination is almost impossible.
Therefore, the recommendation that drivers using E85 should change their oil more fequently is, at best, paranoid. Any dealership service department that makes this recommendation is either ignorant, overly cautious, or after your wallet. If you’re running E85 in your flex fuel truck, stick with the standard 5,000 mile oil change interval, make sure to use the recommended E85 oil blend, and don’t worry about it.
Filed Under: Maintenance Tips