View Full Version : Phase Separation in E10 fuel

12-23-2012, 11:28 AM
Want to learn more than you might really want to know about ethanol fuel and the dreaded phase separation? Check out this study:


I know this is probably way late for the Northern guys, but remember this for next year! Do whatever it takes to find E0 (non-ethanol blended gas) for storing your boat over the winter months. In brief, the study shows that E10 (10% ethanol fuel mix - which has become the US standard) has an increased chance of phase separation as the temperature decreases. The blue stabil will help, but you're much better off with the E0.

If you can only find E15 or E85 at the gas pump, regardless of the time of year, skip the trip to the lake! This stuff will kill your engine.

It's important to avoid having your fuel separate for another reason: your wallet! If you have to have a tank of bad gas drained (i.e. the fuel separated) most dealers will have to charge you a hazard waste disposal fee that could run $8-$10/gal. Do the math on a 40-50 gal tank and you're talking some significant money.

In addition to using the stabil to help fight off the effects of E10, you should also change out your fuel filters often. This is especially important on low use boats. Sounds counter-intuative, but the E10 trapped in there can separate more easily and turn into the brown goo that clogsup your system.

12-23-2012, 11:50 AM
Thanks for the good info. So there is a diff between the red and blue stable?

12-23-2012, 11:54 AM
I'm not really sure if there is a difference as I've never compared the contents of them side-by-side. I was in a class with dozens of marine machanics and they all referred to "blue stabil" so that's what I'm going with.

12-23-2012, 03:40 PM
Yes, the "Sta-Bil Marine Formula" is geared more toward those that are forced to use ethanol blended fuels over the red Sta-Bil.

12-23-2012, 08:22 PM
If you have E10 sitting in your tank for a month without treating it then you need to dump it and I would dump it even treated. I don't winterize with E10 and I don't use E10 in small engines. Too many people with fuel issues with boats and motorcycles that I don't risk it. I go with an near empty tank during the winter and dump that and any any moisture into a gas can and start fresh in the summer.

12-26-2012, 10:04 AM
I curious to know if anyone has actually had an engine issue that was directly attributed to E10 gas. Not, "I think it was E10", but a proven case of it.

I have yet to have any type of failure from lawn equipment (or anything else) which set around for months without use. Perhaps it will happen, but it hasn't yet.

If anyone else took time to read through the article, it was directly related to storage tanks for gas, with no ability to have movement.

12-26-2012, 12:53 PM
Dirt bikes. Seen it happen to a couple of people and sometimes Seafoam can clean it out otherwise a carb rebuild is in order. Call bike shops in an area where bikes are laid up for a while and they can give you some more stories.

12-26-2012, 01:07 PM
In the class I sat in on, many of the mechanics commented on the increase in fuel related issues as E10 has become the standard. While I don't believe anyone stated a catastrophic engine failure related to E10, I believe it's more of an issue of clogging/gumming/mucking stuff up like carbs, injectors, filters fuel lines/tanks that then prevents the motor from being operational.

I let my 4wheeler sit a few months this summer and had made an error in putting untreated E10 in the tank. It has a manual fuel gauge that has a float that rides on rails attached to the cap. When it wouldn't start over Thanksgiving, I pulled the cap and found those rails rusty and the carb is gummed up so much it needs pulled and cleaned/rebuilt.

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12-26-2012, 07:14 PM
Ethanol is more corrosive than gasoline which is why you should not run E85 unless your manual states that it is ok. The ethanol will eat away at rubber components in your fuel system and I suppose it is the residue left behind from gooey corroded rubber that clog things up. E85 vehicles are made with seals designed to resist this aspect of E85.

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12-27-2012, 12:01 PM
I have used Startron for several seasons to preserve ethanol fuel over the winter months. It works as advertised. It stabilizes fuel for up to two years and helps prevent phase separation. I also use Sta-bil regularly during the boating season. The combination of the two seem to keep ethanol fuel in good shape and keeps my engines and fuel system clean and running smooth.


beat taco
12-27-2012, 12:51 PM
On all my motorcycles/atv's I had to start draining the carbs when putting them away for a week or longer due to the fact that they wouldn't start after sitting with E10 in the carbs. Before I was just letting them run out by turning the gas tanks off. It still left fuel in the bowls and I was pulling the carbs every time and cleaning all the gunk out of them. I think it's because the orifices on the jets are so small. So rebuilding 5 carbs to go riding for a day got old fast. I could go to race gas but have had no issues since I started draining the bowls.
I have never had any issues with my lawn mower, I leave gas in it all winter and it still works.

engines have a few things different then a regular gas engine. Internal engine parts receive a nitride coating to resist the formic acid created in the combustion of e85 due to the fact that it absorbs so much moisture. They also have different spark plugs and injectors that pulse more fuel.
SEMA released news of a study that shows e15 and e20 can damage engines. The Coordinating Research Council (CRC) tested 8 vehicle types from '01-'09 model years with various popular engines. Two engines failed while running e15 and e20 gas. And from the report "ethanol increases water formation, which can then create formic acid and corrode metals, plastics, and rubber, which is against the EPA's approval of e15 in '01 and newer vehicles" says SEMA, who has asked congress to enact legislation to stop the sale of e15 until further tests can be done.
Thanks for the report Wolf, good read!

12-27-2012, 02:01 PM
My mower started having issues 2 summers ago. Now every year when i start it up i have to spray carb cleaner into the air intake, then she starts up, though out the year once or twice i have to repeat with carb cleaner to keep her starting smooth.

12-28-2012, 01:04 PM
Last year i got out a mower that had been sitting for about 2-3 years without being run, it was my sisters mower and she moved away and left it sit with the old gas in it. I bought it off of her and tried to get it running. I could get it to start but it seemed like it was always starving for gas and would stall randomly. I pulled the carb out of it and tore it apart and it was totally covered inside with varnish and the needles and float were all clogged up. I know for a fact that she used regular low octane gas from the gas station. leaving this gas in the mower without any type of additive will mess up the carb. I'm sure its not good for injectors after seeing the carb.