I said label "like" unleaded, you know something that tells you it is E85 capable. Like a bright yellow gas cap. Humbling experience when you think you know it all and find out you don't isn't it? Don't worry, happens to all teenagers.

Derek, don't get your feathers all out of kilter. I'm sure this was a bit of a humbling experience for you, having to explain where your thought process went wrong.

When I've been at this point in similar situations, I have found it best to take a step back, admit that I screwed up, and then do what is required to fix the problem rather than fixing the blame. Fixing the blame doesn't get things working again as fast as fixing the problem.

I am in that process right now as I undo some trades that I placed in the wrong account for a client. I screwed up and was quick to admit it. People know we're not perfect. Nobody likes mistakes but most people accept that they happen. I have found that just being big enough to stand up and admit that I screwed up, then doing what it takes to fix the problem, is the best solution.

Taking personal accountablility for our mistakes is one of the biggest lessons I've tried to teach my children. It can be tough, but doing that earns the respect of people around you....and that's a good thing to have.

Life's lessons can be tough. You just paid what my dad used to call "Tuition in the school of hard knocks". Sometimes that tuition is very expensive, some times it ain't. But ya gotta learn to pay it and get on with your life.

I am also 99.9999999% sure that somewhere in the manual, it tells you how to differentiate between the two options.

2006 F150 Owners Manual

Without reading the manual that D linked, I can almost guarantee you that is doesn't explain much. Most owner's manuals have very little technical information in them. Especially a Ford!

In the manual on page 296 you can read

"Your vehicle is designed to use “Regular” unleaded gasoline with pump (R+M)/2 octane rating of 87."

I don't know anyone who thinks E-85 is a regular unleaded gasoline. The term "unleaded" is used to specifically to describe gasoline. E-85 also has an octane rating of 105, another clue.

That is part of the problem with trying to use E-85, to get back the inherent BTU power loss the engine can and needs to be of higher compression to get the most out of the alcohol based oxygen rich fuel. That is why flex-fuel vehicles are kind of a silly thing to have unless the engine's CR is variable.

I told a guy just the other day to stick a corn cob in his tank. I didn't reference the owner's manual first. Just saying.

Update:

The tank and fill line had an anti-siphon valve in it, so that idea was out. He burned about 1/2 of the tank and filled it with regular gas. The check engine light went off by itself and the engine is back to running properly and powerful.

D

Bull-oney! I dare you to try to do simple tasks on your newer vehicle without one. Anyone who brings me a newer vehicle for a pre-inspection check, I always tell them that an owner's manual is a must before signing any papers.

I can't think of one flex-fuel vehicle that doesn't have some sort of signage inside the gas door.

I had a customer who loaned their TDI VW to someone who put gas in it! It came out OK, just a drain, filter change and flush. Expensive tank of gas though!

Glad you find them useful CNY. But for functions more complicated than changing radio settings, setting the light delays, and stuff like that, they almost always refer you to your dealer. They don't explain a lot a all. But you are correct, they come in handy when you are trying to turn off that darned "Change oil soon" light, or the "low tire pressure" one.

I find the manuals have good specs in them, such as valve clearance, fluid types and volumes, spark plug models and gaps, belt tension, etc.

But in a situation where the vehicle can be optioned with either engine, the manual doesn't have much ability to help, other than say LOOK HERE at the vin or if there is a logo elsewhere on the truck.

I'm about 99.9999999999999% sure the Tahoe does not say something special in the gas door. I'll look next time though. It was built back in the day where E85 was WIDELY not known about (purchased late 03 as 04 model).

Regardless, appears as if problem is solved.

Manual for my truck says pretty much nothing about Duramax/Allison. There is a separate "supplement" manual for that.

Best use I've found for manuals is the towing charts with all the GCVWR combinations of body style, engine, axle, etc. and fluid specs & volumes.

My oil fill cap is yellow...can I put E85 in there? Bet it won't be long before the flex fuel caps are "green"!!!!!

Good point HB.

Except that green has sort of been the accepted color for diesel fuel pump handles for years.
I thin the bright yellow nozzle at the stations and the yellow fuel fill cap is just fine.

True...I've seen a few stations that had green for gas and black for diesel. Had to really look at the pumps close! Smelling the nozzle helps too