Long Term Effects of E85 on "Rubber" Bladder

All, a quick update. The car now has 85.5k miles, which is 23k miles on E85 exclusively. It still runs like the day it rolled out of the stealership. So, for now, no noticeable effects on the tank bladder. Once I get to 100k I'll replace my spark plugs and PCV valve, which will be a great opportunity to take another peek at the cylinders with the endoscope. I will continue to keep you updated as time goes on.

Also, I recently moved, and my commute has changed significantly. I now put 100 steep and curvy mountainous miles on the car on a daily basis. No flat ground nor ability to hypermile. Ambient temps between 32˚F and 59˚F. Hence, my mileage has dropped from 40-41 MPG to 35-39 MPG.

edthefox5, I believe we are barking up the wrong tree when it comes to TAN. After some research, TAN measurements are mainly used for hydraulic oils. Crankcase oils on the other hand, can benefit more from TBN tests. In fact, it seems as if some virgin oils can even start with a TAN value well above 0.

Additionally, comparing a TAN value from a transmission oil to that of one of an engine oil is like comparing apples and oranges (i.e. oranges are more acidic). Even comparing a TAN value of one type of engine oil to that of a different engine oil would not be valid. Hence a transmission oil TAN value does not have much purpose in this thread. While I do think more info is a good thing, I would like to keep the conversation appropriate to the E85 topic (E85 use should not have much correlation to trans TAN values).

Something to note about TAN is that it is commonly misconstrued for acidity of oil. Acidity (acid strength) is typically read on a pH scale, which is different than TAN/TBN. TAN represents the concentration/amount of acidic components in the sample. TBN provides the concentration/amount of active alkaline additives remaining. What this means is that a high TAN value can be offset by a high TBN, and not result in an acidic (and hence potentially harmful) oil. Seeing that TBN values are quite high in this engine oil, the oil shows good potential to keep an acidic situation from happening.

It is possible that using an inferior oil with fewer alkaline additives could present a problem with E85 use. However, this theory is not being tested. The use of Toyota synthetic oil seems to be working well, and the purpose of my E85 experiment is primarily to test tank bladder compatibility.

 

Hey all, car is now at 117k miles, and it still drives great, no issues whatsoever. So that’s around 55k miles on E85 exclusively. Have never filled up with gas since adding the piggyback computer. I’m gonna say that E85 doesn’t have any noticeable effect on the bladder or any other fuel component.

I have inspection videos of the pistons and cylinder walls from the spark plug change at 100k and everything still looks new. No oil consumption either.