2500 Mile Oil Changes Because You’re Running E-85? P-shaw

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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.

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  1. Bob Moffitt says:

    Nice post, Jason. I was one of the first to challenge the Wisconsin dealership’s message on Twitter. I’m the communications director for the Clean Fuel and Vehicle Technologies program of the American Lung Association of the Upper Midwest. We have extensive experience with E85 and biodiesel. Those interested in these cleaner-burning biofuels should visit our CleanAirChoice.org website.

  2. Thanks Bob – feel free to Tweet about this post! 🙂

  3. Mickey says:

    I think if they went with the old at 3,000 it wouldn’t have been that bad. Some people still do that with these new engines. Sounds like someone covering thy butt if something goes wrong. The sky is falling you know.

  4. manny says:

    i have an 2007 tundra crew max limited with 5.7 it was in an accident and i am replacing it with a 2010 the dealer can only get a flex fuel version are there any negatives to it . is the power the same if i dont run e85

  5. mk says:

    I am not a big fan and would not use E85 for several reasons. For one, you get about 25% less fuel economy (basically 13 avg. mpg. vs. 17-18) and the cost benefit is not there since as of now, E85 is not even close to 25% cheaper unless gas goes back to over 3.50 per gallon or so. Not only that, but here in the midwest, farmers are in short supply of corn and could use that corn to more benefit to feed hungry people vs. gas guzzling vehicles. I had a chevy 5.3L silverado and hated the effects of E85 on my truck. Supposedly, it is higher octane fuel which in reality burns quicker but is suppose to make the engine have better pickup and performance. I experienced just the opposite with E85 running it exclusively for several months and experiencing 13 mpg vs. normal 18 mpg, hard/jerky shifts between gears at times, worse performance/pickup off the line and at times a few knocks and pings coming from the engine. I got confirmation from a reputable toyota dealer and the service dept. recommends to ONLY change the engine oil every 2500 miles ONLY if you use E85 fuel 50% or more of the time. Otherwise, the 5K oil change interval is fine. If I did get an E85 2010 tundra, I would definitely ONLY use E85 every once in awhile (less than 25%) since I feel it is worse for the engine over the long haul if you plan on keeping your truck for over 5 years and 100K due to engine damage it could cause over 5 years or more.

  6. Manny – There’s no appreciable difference between a flex-fuel 5.7 Tundra and a regular gasoline only 5.7 Tundra. mk lists off a few negatives that come with using E85, and I would echo his endorsement to stick with regular gasoline only. Still, the engines are basically the same.

  7. mk says:


    thanks for the vote of confidence concerning my post. I thought I was going to get bombarded with negative feedback because the article portrayed
    E85 as being really worthwhile to use and not really any negatives about using E85 vs. E10 gas. I was just posting my life experience using E85 and although cheaper to buy, it is not the almightly solution to fix our dependency on foreign oil. I would use E85 sparingly and not over 50% of the time and all should be fine-hopefully in the long haul?

  8. mk – The article wasn’t meant as an endorsement for E85. However, there are some places in the Midwest where E-85 is dirt cheap ($1.00-$1.50 per gallon), and in those places E-85 makes some sense…especially as gas prices start to creep back upwards. For most drivers gasoline makes more sense, but not all.

  9. MrPote says:

    Manny – If u want to buy the TRD Supercharger, I think u can’t use it with the flex-fuel engine. Just search for that info, just in case. 😉

  10. Manny – MrPote is correct.

  11. Justin says:

    Before dismissing this theory (recommendation), maybe some research into other manufacturer recommendations (who have been making FFV’s since the late 80’s/early 90’s) and maybe changing your oil after running E85 for 3K miles would help too.
    Example: Vehicle is an 04-08 F150 5.4L FFV. Ford recommends an oil change every 5 months/5K miles when running 87 octane gasoline. They recommend an oil change every 3 months/3K miles if running E85 50 percent or more of the time. Being I own this truck and have tested it, I too would recommend changing your oil every 3 months/3K miles if running E85. First off, the smell of the oil when running E85 is horrid, one of the worst smells I’ve come across. Secondly, the oil was much darker and broken down at 3K miles than oil is when using 87 octane. So my personal experience says, they know what they’re talking about, being they’ve most likely conducted many hundreds of thousands of hours on R&D. Nothing beats 1st hand experience to me.
    Now I do admit, running E85 gets worse mpgs, especially on the highway (F150 droped from 18-20hwy to 14-16hwy). But it does provide a slight power boost (seat of the pants feeling) and throttle response over your basic 87 octane. Also for those that think it only costs $1-$1.50 or whatever the pump states, you must also remember and calculate in the susidies the ethonal manufacturers receive. So you may not notice the additional cost at the pump, but you are paying more for it, whether or not you use E85. When cost effective (has to be 70-75 cents less than 87 octane to counter mpg decrease based on my calculations) I try to use it, since my E85 station uses strictly CO manufactured ethonal, and being I live in CO, I prefer to keep the money in state.

  12. Justin – Good comment as always. I’ve spoken with a few technicians about this in the past as well as some manufacturer reps, and everyone seems to think that the 2500-3000 mile interval is a recommendation erring on the side of caution (at best). Provided that you’re using the manufacture recommended E85 oil blend, you should have no oil issues running E85 for 5k miles between changes. Still, it can’t hurt to go sooner. My problem with this type of recommendation is that manufacturers and dealers have been saying “3k miles” for the last 40 years despite the fact that oil and engine technology has changed dramatically in that time – simply put I don’t trust them at all on this issue. Auto manufacturers and auto dealers have a vested interest in recommending overly frequent oil change intervals, so I believe we should take their recommendations with a grain of salt. Personally, I think the 5k mile interval is a little excessive for a normally driven vehicle – 7500 to 10000 miles is probably fine if you’re good to your ride. Having said that, I stick with 5k in my personal vehicles simply because I don’t want to risk it. So I guess I’m a hypocrite…

  13. mk says:

    5K is about right between oil changes. I do not let it go much over 200-300 miles over that. Not worth the risk if you plan on keeping your vehicle for a long time. I always use to change oil every 3-3.5K only a few years ago, but more and more mfgs. are stating every 5K, so I trust them to know what they are talking about.

  14. […] *24mpg/28mpg. More food for thought…another expert tells us " DON'T WORRY ABOUT E85!" http://www.tundraheadquarters.com/bl…-running-e-85/ […]

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