Should I try running E85? Or stick with unleaded.

[Chiller449]

So out of curiosity I did a vin decode on my 2004 Tahoe. To my surprise it said I have the flex fuel 5.3. My dad has owned the truck since it had 150k on it. Ive owned it for a while now and its got 255k on it. Still running like it was new. Im 100% positive my dad has never ran e85 in it. As for whoever owned it before him I have no idea. Im just curious if you guys would suggest trying e85 or just sticking to unleaded. Im not sure if it would hurt the engine now that it has such high miles and never used e85 before.

Also here is the vin incase you wanna run the vin. The site I used looked a bit sketchy and may not be right.
1GNEK13Z34J214410

 

[Big Mama]

E85 imo is for when that’s all you can find. It was supposed to be cheaothan gas back then but it never happened. In the boat world, I have a 350 in mine, ethanol is the devil bc it gums up if you don’t run it regularly. With today’s gas prices fill up with premium and give her a treat.

 

[swathdiver]

So out of curiosity I did a vin decode on my 2004 Tahoe. To my surprise it said I have the flex fuel 5.3. My dad has owned the truck since it had 150k on it. Ive owned it for a while now and its got 255k on it. Still running like it was new. Im 100% positive my dad has never ran e85 in it. As for whoever owned it before him I have no idea. Im just curious if you guys would suggest trying e85 or just sticking to unleaded. Im not sure if it would hurt the engine now that it has such high miles and never used e85 before.

Also here is the vin incase you wanna run the vin. The site I used looked a bit sketchy and may not be right.
1GNEK13Z34J214410

Vin Z, L59 motor right? You can run E85 with no ill effects. The truck will love it, it's like burning cheap racing fuel. Try a couple of tanks, one isn't going to give you a good report of E85s performance or your truck on it as the alcohol content will be diluted from the previous fill. On the other hand, if its really cold where you live, know that it might stall on start up as the fuel in the lines will be quite cold and the motor won't like that. Once running it'll be fine though.

Where do you live and how much is it per gallon and how common is it? I know of eight stations in my county now, double from a year ago.

 

[Chiller449]

Vin Z, L59 motor right? You can run E85 with no ill effects. The truck will love it, it's like burning cheap racing fuel. Try a couple of tanks, one isn't going to give you a good report of E85s performance or your truck on it as the alcohol content will be diluted from the previous fill. On the other hand, if its really cold where you live, know that it might stall on start up as the fuel in the lines will be quite cold and the motor won't like that. Once running it'll be fine though.

Where do you live and how much is it per gallon and how common is it? I know of eight stations in my county now, double from a year ago.

I live in indiana near lake Michigan, It can get quite cold this time of year. E85 is pretty common around here. I would say atleast 25-30 stations have it within a 50 mile range. It costs around $1.85 a gallon. So you think the truck will run just fine on it even with 255k miles? Also how can i be sure i have the L59 motor? any marking i should look for on the block or something?

 

[swathdiver]

I live in indiana near lake Michigan, It can get quite cold this time of year. E85 is pretty common around here. I would say atleast 25-30 stations have it within a 50 mile range. It costs around $1.85 a gallon. So you think the truck will run just fine on it even with 255k miles? Also how can i be sure i have the L59 motor? any marking i should look for on the block or something?

Your VIN and RPO code. The engine's look identical between the LM7 and L59 but you will have much larger fuel injectors and the rail might be different. I'm not familiar enough to tell. Also, yours has an alcohol content sensor and your original gas cap was yellow. If you have a good scan tool or fancy OBD adapter, you can view the alcohol content whereas a regular truck will not have that feature.

 

[Chiller449]

Your VIN and RPO code. The engine's look identical between the LM7 and L59 but you will have much larger fuel injectors and the rail might be different. I'm not familiar enough to tell. Also, yours has an alcohol content sensor and your original gas cap was yellow. If you have a good scan tool or fancy OBD adapter, you can view the alcohol content whereas a regular truck will not have that feature.

Where can I find my RPO codes? Are they still in the glovebox like they were back in the day? My gas cap is currently black but i have no idea if its original or not.

 

[swathdiver]

Where can I find my RPO codes? Are they still in the glovebox like they were back in the day? My gas cap is currently black but i have no idea if its original or not.

Yes, should be inside the glovebox door. If the sticker is gone, you can get it from GM in a chat session or email. They'll send the whole breakdown.

 

[Chiller449]

Yes, should be inside the glovebox door. If the sticker is gone, you can get it from GM in a chat session or email. They'll send the whole breakdown.

Found the RPO codes. It does say L59 on it. If I calculated right to break even E85 would have to be about 27 cents cheaper than Regular. This assumes im getting an average of 15mpg on gas and 13 on E85. I might try it if gas gets high in my area again. Currently they are pretty close. E85 is only about 15 cents cheaper.

 

[swathdiver]

Found the RPO codes. It does say L59 on it. If I calculated right to break even E85 would have to be about 27 cents cheaper than Regular. This assumes im getting an average of 15mpg on gas and 13 on E85. I might try it if gas gets high in my area again. Currently they are pretty close. E85 is only about 15 cents cheaper.

I see about 3 MPG less burning E85 compared with 93 octane gasoline on average. It costs about $.04 less per mile to use E85 than 93 octane over the last thirteen months. The current spread is even greater as E85 around here has fallen in price a little more than gasoline.

With fuel prices always fluid, pun intended, E85 is not always the best value but the motor loves it, drives different and makes more horsepower and torque.

 

[Big Mama]

Chris, do tell about E85 it’s seems I had it all wrong. In VA our pump gas had up to 10% ethanol and it’s awful for boats. I do run pump gas for the first few months of boating bc I’ll burn it up but at the end I use ethanol free and stabilizer. Engine is late 80’s model 5.7 marine engine. Is it bc carburetors?