I bought my 06 Monte Carlo LT and the 8th digit of the VIN is K. According to the owner's manual it should be capable of flex fuel. I also checked a website that runs VIN numbers, and it shows flex fuel capable.

The website E85 | How can I tell if my car is an FFV? also says the 06 LT is capable. The problem is the gas cap has a sticker that says do not use fuel with E-85 additives.

Does anybody know if I can use it, or should I just visit the dealership and inquire?

 

I would check with the dealership, is the engine the stock engine and everything?

I wonder if maybe replacement parts were used and they just found a fuel cap that works or if maybe the engine is swapped and not designed to be used with e85?

 

I'd say the same thing go to a dealer and have it checked out before you do so. Thats a mystery to me.

 

From what I can tell the engine was never replaced. It's only had 2 previous owners. The guy before me did some funky stuff to it though, so it may have been a replacement part. Think I'll just take it into the dealership, and yes, it is all stock under the hood.

 

It might just be a new gas cap because of EVAP codes. But you can always ask to make sure if it it okay.

 

Are you sure that sticker doesn't say do not use additives with E85 fuel?

 

It sure does...don't I feel retarded now haha. Means I can go give it a shot and see what's up. Anybody know what kind of mileage you get E85?

 

Fuel mileage will be a good deal less with E85 I can tell you that much. I lose 2-4 mpg on the highway with the 10% ethanol blend alone as opposed to "pure" 100% gasoline. So I imagine E85 would be even less than that.

 

I do a lot of driving, and with the 10% ethanol blend I'm only averaging anywhere between 20 and 23 mpg, so even if I lose a couple (depending on the price difference between E85 and gasoline) it may be worth it since I drive so much (400+ miles per week). I'll check the price of E85 today and see what's up though, might be worth looking into for me.

 

Gas mileage is worse, but you can tune more aggressively for e85 (if you tuned).

But it is supposed to be cheaper per gallon.

Overall, I think in the end it's all the same.