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-   -   4.8 Mileage Tips? (https://www.truckforums.com/forum/chevy-silverado-gmc-sierra-forum-11/4-8-mileage-tips-20816/)

GMC_Chris 08-08-2015 09:11 PM

4.8 Mileage Tips?
 
I've got the 4.8 L/4 speed combo. Its a dandy little motor and I'm very happy with it. I'm torn on the tranny, the 4 speed is an iron-clad piece, but the 6 speed would save me a ton on gas I think. That said, other than driving style, anybody with a 4.8 have any tips on saving a bit at the pump?

I'm working on my driving style. I'm coming off a Grand Marquis, so I've gained a lot of ponies and went from a 2.76 (est) rearend to a 3.42. That means my usual throttle tip-in is too much for the truck. I'll adjust as I drive it. Fist 1/2 tank is at 15.7 MPG right now, with about 60% hwy and 40% town/city. I can live with that, but a few more MPG's would be better.

Granted, I will IN NO WAY give up my truck for a bit of savings in gas! I've waited too long for it and need it too much!

primem 08-09-2015 02:43 AM

I have a 5 speed manual with my 4.8. my mileage is 16mpg city and 24 highway imperial gallon.
I would gladly trade for the 4speed auto. the manual has 2000lb less towing capacity and no torque multiplication for any type of pulling power. the darn thing is still on it original clutch so I can't fault it.


Once your up to speed and in top gear I bet the overdrive ratio's for the 6sp are the same or close to the 4sp.


for mileage:
don't drive with the tailgate removed or down - you will lose 1mpg. the tailgate up position allows an aerodynamic bubble to set up that sends air over the back of the truck
don't replace the tailgate with a mesh strap tailgate- lose more than 1mpg as it acts like a parachute
install a tonneau cover will improve mileage 1mpg...that's why all hybrids come with soft tonneau covers from the factory

GMCSierraFan 08-12-2015 01:09 PM

My 13 has the 5.3 with AFM, Z-71 etc, and a truxedo tonneau cover. Came with A/T tires that probably don't help.

City(Chicago): 17.5 mpg

Highway w/cruise: 21mpg
Highway w/out cruise: 22-24mpg


I'm curious to try ethanol as it is about 40% cheaper than gas, but I've always chickened out at the last minute lol. I have not run premium yet.

This is running regular unleaded 87 (which is up to 10% ethanol in WI)

primem 08-13-2015 06:56 PM

I've read that afm will improve mileage up to 4%. be happy you have a 2013 and not a pre November 09 afm 5.3.




if you go CH3CH3CH30H fuel....there may be a minimum fill requirement...some brands won't register a fueling event in the volume it small. check you owners manual. I not sure if this would effect the fuel ratio compensation or if the composition is based on live fuel data from the ethanol content sensor.


I hate enthanol blended fuels. if you run small engines get ethanol free fuel for it.

GMC_Chris 08-13-2015 08:35 PM

I generally run ethanol blend (10%) 87 octane. Its been my experience that mileage savings on premium are minimal unless your motor is designed for it. Nobody around here sells E85. Your mileage may be 40% or more worse, but I haven't used it in a modern E85 engine.

GMCSierraFan 08-14-2015 08:43 AM

I put in E85 and will start a separate thread detailing what I find.


I do have to agree about not running the 10% blend in small engines. I found after a trip to Minnesota in January that my little 02 Honda 2.3 V-tec ran very rough when it was cold on the 10% blend. I could have been paranoid, but I found a station with regular unleaded once I was back in the southern midwest and it didn't happen again


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