MPG/power observations while towing

I have used my truck to tow around 5000K miles in the past 6 mo's. I have used 87, 91 and 93 octane fuel. The manual for my 08 AC 4.0 says to run it with 91 or higher but it is okay to run other octanes. Here are my observation.

87 oct. pulls good but it must be in 4th gear all teh time and needs to downshift to 3rd on inclines. average mpg is 10.4

91 or 93 oct. pulls noticeably stronger and does not downshift into 3rd on inclines unless it is reaching 5-8% incline at highway speeds. Furthermore it can run in 5th gear on relatively flat runs locked in at 2000-2300 rpms @ 55-65mph with little or no hunting. the higher oct also gives it 11.7mpg.

So, in My experiences, Higher oct has more power, lower running rpm, and better mpg. Seems like a no brianer to me to run 91 or higher when towing or heavily loaded.

Here is a pick of my loaded rig. TT- 4000lbs, Truck cargo with passengers/dog around 1000lbs

 

You're probably getting better performance while towing with premium because of anti knock sensors in modern engines retard ignition when pre-detonation is detected. That's the only thing premium gas has over regular.
http://www.servassistonline.com/Consumers/high_octane.php

 

kinda late to this post but i should be safe then in towing a car at 3500lbs (actually 3300) and a uhaul trailer then huh?

 

Yup. I get some pre-detonation with 87 with out a load but 89 takes care of that so that is what I use in town. As you stated the premium stops pre-detonation so there is no need for the timing to be retarded. I had to use 87 in some places this summer because that is all they had. I have not hauled with 89 but I will try it some time to see how it works.

Good write up as well.

Thanks, Paul

 

Should be fine with the right hitch and I believe the uhauls use surge brakes.

If you rent from uhaul it has been recommended on this site several times to tell them you will be hauling something light like a Ford Festiva or something like that because they will not let you rent the car hauler if they think you will be overloaded or past the limits of the truck. I believe their car hauler trailers weigh in at around 2000lbs. here are the specs

paul

 

My 2011 DC V6 4X4 gets 21+ MPG with no trailer, but towing does bad things to the mileage. I'm towing a 3300 dry (probably about 3800 wet) camper and, on secondary roads 45-50 MPH I can get 15 MPG. However, at turnpike speeds at 65-70 MPH on cruise control I average just under 10 MPH. I can get a little more without cruise. The good news is that the Tacoma pulls without any power or sway issues and is very comfortable doing it.

 

MAN!!! 15mpg on the back roads or any roads with that weight and wind resistance is unheard of to me.. I have never had better then 12.5. Most of my numbers above are from 55-65 mph on all types of road. I don't carry the bike very often so our rigs are similar weight for most of my traveling.

Looks like the rear of the truck is sagging a bit. May need to adjust the WD or if you have not added leaf spring that may help too. I do not know if the 11's have the TSB for the rear springs. you may want to check. It made a big difference when towing on my truck. I t will make the ride a little more stiff when not loaded though.

 

wow that is incredible mileage towing and not towing w/ your truck.
I never saw those numbers with my 06 DC 4x4 auto, maybe 20 a couple of times.
I towed primarily winter time with an 8x12 enclosed clamshell snowmobile trailer.

 

I had similar results once with my Ridgeline in Oregon on backroads. I was surprised how much the mileage went up driving 50. On level roads weight doesn't have as much effect as wind does. My recent experience towing a 9000lb 5th wheel I got the same mileage as pulling my old 4000lb. tt.