# EPA and e15, 88 octane. Are you worried? **URL:** \ **Category:** General Discussion\ **Created:** [March 30, 2026, 11:48pm UTC](https://community.cartalk.com/t/epa-and-e15-88-octane-are-you-worried/205435 "2026-03-30T23:48:02Z")\ **Posts on this page:** 9\ **Page:** 2
**Author:** ![Nevada\_545](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/nevada_545/32/41232_2.png) [@Nevada\_545](https://community.cartalk.com/u/Nevada_545)\ **Post date:** [April 6, 2026, 10:11pm UTC](https://community.cartalk.com/t/epa-and-e15-88-octane-are-you-worried/205435/21 "2026-04-06T22:11:01Z")
> [@bing](#): > > We had a driver that twice put it in a non flex car. Cost about $2000 each time for repairs. Sounds like a fair price for a person or company with a big budget. Seems they took extreme measures to “decontaminate” the fuel tank. When customers had a check engine light caused by E85 in a non-flex fuel vehicle, I drained the fuel from their tank into mine. 2 hours of labor to diagnose and repair. ---
**Author:** ![TheWonderful90s](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/thewonderful90s/32/29584_2.png) [@TheWonderful90s](https://community.cartalk.com/u/TheWonderful90s)\ **Post date:** [April 6, 2026, 10:57pm UTC](https://community.cartalk.com/t/epa-and-e15-88-octane-are-you-worried/205435/22 "2026-04-06T22:57:43Z")
> [@Nevada\_545](#): > > When customers had a check engine light caused by E85 in a non-flex fuel vehicle, I drained the fuel from their tank into mine. 2 hours of labor to diagnose and repair. Was it a Ford? It seems like Fords from the late 1990s will adjust the fuel extra rich if necessary to keep it running. Lets it still run on old gas or with other problems. e85 in my 1996 F150 would be an interesting experiment. I would put a few gallons in and then go back fill it with E0 to dilute it back to the E10 that it is rated for. If it is rated for E10 it would probably take a while for E85 to eat away plastics and rubber, but I wouldn’t chance it. As far as E15 the same rules apply as E10. E10 is about 0.95 the fuel economy as E0. In some non optimally tuned vehicles it is far worse than 0.95. E15 would be 0.92 or so. So the cost better be 0.92 as much as E0 or 0.97 as much as E10 to make it worth while, and it usually is. I think Ethanol replaces another octane boosting or emission reducing additive that is more toxic to the environment. If the fuel system isn’t seal (mostly anything that’s not a car or fuel injected), or it doesn’t get refueled within 3 months, use non ethanol. The first half gallon in the pump hose may contain the previously purchased fuel. ---
**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\ **Post date:** [April 7, 2026, 12:09am UTC](https://community.cartalk.com/t/epa-and-e15-88-octane-are-you-worried/205435/23 "2026-04-07T00:09:23Z")
> [@TheWonderful90s](#): > > Was it a Ford? It seems like Fords from the late 1990s will adjust the fuel extra rich if necessary to keep it running. Those would be the flex-fuel Fords, built to handle E85 ---
**Author:** ![Nevada\_545](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/nevada_545/32/41232_2.png) [@Nevada\_545](https://community.cartalk.com/u/Nevada_545)\ **Post date:** [April 7, 2026, 12:31am UTC](https://community.cartalk.com/t/epa-and-e15-88-octane-are-you-worried/205435/24 "2026-04-07T00:31:35Z")
> [@TheWonderful90s](#): > > Was it a Ford? It seems like Fords from the late 1990s will adjust the fuel extra rich if necessary to keep it running. 1996 Dodge. Every PCM will add 25% short term and 25% long term to the fuel system (33% for 2001 and up). If the long-term fuel trim reaches 25%, emission output increases and the check engine light will illuminate. If I had to drive 85 mph on the highway, the high ethanol content could cause engine damage due to the lean mixture. At 45 mph in the city, I am not concerned. ---
**Author:** ![TheWonderful90s](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/thewonderful90s/32/29584_2.png) [@TheWonderful90s](https://community.cartalk.com/u/TheWonderful90s)\ **Post date:** [April 7, 2026, 2:59am UTC](https://community.cartalk.com/t/epa-and-e15-88-octane-are-you-worried/205435/25 "2026-04-07T02:59:34Z")
> [@Nevada\_545](#): > > If I had to drive 85 mph on the highway, the high ethanol content could cause engine damage due to the lean mixture. So if you run E85 in closed loop the oxygen sensors would keep the mixture correct, or not? I thought with E85 it would hit the 25% fuel trim limit and start to run lean. As long as there is no check engine light, then no issue? ---
**Author:** ![Nevada\_545](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/nevada_545/32/41232_2.png) [@Nevada\_545](https://community.cartalk.com/u/Nevada_545)\ **Post date:** [April 7, 2026, 5:20am UTC](https://community.cartalk.com/t/epa-and-e15-88-octane-are-you-worried/205435/26 "2026-04-07T05:20:05Z")
E85 will cause the fuel trim to reach the maximum limit, run lean and illuminate the check engine light. A lean fuel mixture will elevate the oxides of nitrogen (NOx) output, the reason for the check engine light. Operating with a lean mixture at city speeds won’t melt pistons. In my case, 10 gallons of E85 was added to a fuel tank that had 5 gallons of E10 fuel. The fuel mixture was no longer 85% ethanol. ---
**Author:** ![bing](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/bing/32/4619_2.png) [@bing](https://community.cartalk.com/u/bing)\ **Post date:** [April 9, 2026, 8:53pm UTC](https://community.cartalk.com/t/epa-and-e15-88-octane-are-you-worried/205435/28 "2026-04-09T20:53:28Z")
Ten character minimum. ---
**Author:** ![Purebred](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/purebred/32/46796_2.png) [@Purebred](https://community.cartalk.com/u/Purebred)\ **Post date:** [April 11, 2026, 1:07pm UTC](https://community.cartalk.com/t/epa-and-e15-88-octane-are-you-worried/205435/29 "2026-04-11T13:07:21Z")
My car allows 87 octane gas but recommends 93. Yesterday filled it with 90 octane **non** -ethanol gas, $0.40/gal **less** than 93 gas with “up to” 10 percent ethanol. Though next fill up will be the 93 octane. I have not seen 15% or higher gas **yet** in my area in Florida. ---
**Author:** ![davesmopar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/davesmopar/32/41750_2.png) [@davesmopar](https://community.cartalk.com/u/davesmopar)\ **Post date:** [April 11, 2026, 2:26pm UTC](https://community.cartalk.com/t/epa-and-e15-88-octane-are-you-worried/205435/30 "2026-04-11T14:26:57Z")
> [@Purebred](#): > > I have not yet seen 15% or higher gas **yet** in my area in Florida I have yet to see E15 around here either… Most everything is E10, very hard to find E0 unless you already know where to get it… We have 87, 89 and 93, but the E0 is normally 90 octane… Gas prices have started to lower a little bit the last few days in my little part of the world… EDIT: Yup, gas dropped $0.12 a gallon over the last couple of days, was $3.999, now $3.879 at the Exxon, Kroger and twin Mapco’s… Did not see Shell, but it is showing on line to be $0.05 less… [Previous page](https://community.cartalk.com/t/epa-and-e15-88-octane-are-you-worried/205435.md?page=1)