Waking up the 5.3

[MikeNH]

I'm a little under quarter tank of fuel right now. How empty shoud te tank be to go ahead and try e85? Also, is their any issue going back to regular unleaded after using the e85

 

You're fine to do it now. They say you want to add at lead 7 gallons I think but in reality you're going to need several tanks to be run through before you'll get a real idea of how the truck is on E85. Your manual covers this in detail.

[gilleydog]

about the best mod that i have used the sprint booster , airaid jr tube kit with aim dry filter and e85 even the wife noticed how much more get up a go

[POS VETT]

I'm a little under quarter tank of fuel right now. How empty shoud te tank be to go ahead and try e85? Also, is their any issue going back to regular unleaded after using the e85

The engine has an alcohol-content sensor. The PCM calibration allows nearly any alcohol concentration to run the engine properly. The changes in engine parameters are instantaneous and going back to E10 (regular gasoline) will not cause any problem.