Long Term Effects of E85 on "Rubber" Bladder

Hello PriusChat,

Ever since purchasing my Prius, I've never hesitated to browse these forums when in doubt, and I'm thankful to all of you for having taught me so much. A lot of you post great info, and I will try to do the same.

I would like this post/thread to be an informative one. Many threads have arisen regarding E85. After reading them all, I haven't been able to form a solid yes or no as to whether or not the 'rubber' tank bladder in our beloved US market second gen Prii can withstand gasoline fuel with a higher ethanol content than 10% (E10), for a prolonged period of time. I've found many threads to contain many opinions and predictions, warning of pricey repair costs, with little to no actual empirical evidence.

I found others in foreign countries (no bladder) use higher ethanol content gasolines successfully. This tells me that all but the tank bladder has been tested.

I'll use my Prius as a guinea pig.

Before some jump on me warning me of expensive repair bills, I fully understand the risks of my actions.

Again, I fully understand the risks of my actions.

I'm lucky enough to have worked as a mechanic for some years, have a source of cheap OEM parts at a local stealership, and have had the experience of working as an engineer for multiple automotive manufacturers.

Current state of affairs that may be relevant:

• 2008 Prius Touring, US/California model. I bought it new in fall/winter 2007.
• 62.5k miles (While this is my daily driver, I don’t end up putting too many miles on it since I own many other cars).
• 53MPG for the last 25k miles, as per the MFD readout (I will calculate my MPG manually once I start using E85).
• I try to keep TPS values between 19 and 23 on the freeway, as per a ScanGauge II. The car is babied around, although I did participate in an autocross with it once, since my autocross car was out of order at that moment.
• Every tank has been filled with Shell 87 (AKI) octane (sometimes Chevron when no Shell is available), with up to 10% ethanol (E10). Yes, every single tank.
• Car has been maintained by myself with exclusively OEM Toyota parts and fluids (other than an Optima yellow top). It's great having a parts hookup, although it hasn't needed much honestly! :-D
• Oil changes started out at 2.5k mile intervals. I realized that was extreme overkill and have moved to 5k intervals. Used 5W-30 Toyota branded oil. As of a few changes, I now use 0W-20 Toyota synthetic.
• Oil filters have always been TRD.
• Air filters replaced at 10k intervals.
• Transmission fluid replacement at 35k.
• Spark plugs and PCV replaced at 50k.
• Still on the original Bridgestone Potenzas, although they are close to the wear markers. 50PSI on all four corners for the last 30 or 40k.
• Tanabe lowering springs, tanabe strut tower brace, and a couple more underbody braces installed.
• Large free-flowing muffler installed as a practical joke by friends. Sounds great so I ended up keeping it. Not a fart can, actually a decent muffler. Whether or not the less back pressure is better or worse for mileage, I don't know. Instinct tells me better but I have heard otherwise.
• Long term fuel trim is at 0.7%, as per a recent Techstream readout.

Will soon be installing a Change2E85 kit (made by Fuel Flex International). No other ethanol related mods will be installed, at the moment.

I will try to document as much as I can as I go along and will post to the thread when convenient, whether or not the car runs well or blows up in flames. I will let you all know. Expect an update regarding my first couple of tanks in the next few weeks once I get the kit installed.

 

Hello all,

I've just installed the kit, and have a 50% E10, and 50% E85 mix in the tank. (Installation instructions said to run the first tank 50/50, and then go all E85 from then on. So far, I haven't noticed a performance difference with the 50/50 mix. The car seems happy.

Here is a link to a video showing the tops of my pistons, just before installing the kit.

I also drained a small amount of engine oil to send in for analysis, to get a baseline for how the engine is wearing with E10. After running E85 for a few oil changes, I'll send in another sample for analysis.

Almost. This kit is only software based. A small computer interfaces between our stock ECU and the injectors. It keeps our stock injectors open slightly longer, delivering more fuel. Our injector should be able to handle the extra duty cycles.

 

It has been said that ethanol does not play nice with many elastomers, either disintegrating them or drying them out. I think this is more the case with older components. I take it modern fuel system components designed for prolonged E10 use should withstand E85, but I just don't know. Hence the experiment.

I wondered this too! I'd switch over in a heartbeat if I knew how to! If my bladder goes, I will definitely consider figuring out how to swap in a European market tank.