1,516 miles towing with my Gladiator, 11.2mpg

[MrJeep]

I pulled 6500lbs. from San Diego to Washington State. I kept the speed at 62mph. The 3.6 got 14 mpg. The squat was obvious but she drove straight and I never felt uncomfortable. I don't care to go 7650 in my max tow though.

Yeah, those uhauls force you to put the vehicle too far forward for most cars I have found.
That sounds like my experience towing my TJ. Every time I do it I always get exactly 13.7mpg (non uhaul trailer, it feels a lot better with a brake controller than surge type.)

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[AmishMike]

I’ve towed a lot this year and shifting manually is the trick to better fuel mileage and easier on the truck.
DEFINITELY keep checking engine and transmission temps. You need to stay under 220 for the transmission.

Modern ATF is good to 270*F

 

[XJADDICTION]

Modern ATF is good to 270*F

I always stay on this side of caution. I would not ever like to see 230* with the 8 speed. The ATF May be good to failure but the transmissions… any auto transmission does not like heat. I had gauges for all my diesel transmissions and watched them like a hawk.

from advanced transmissions;
“The optimal temperature range for transmission fluid is 175 to 220 degrees. Above that, for every 20 degrees bad things happen, starting with formation of varnish at 240 degrees, followed by seals hardening, plates slipping, seals and clutches burn out, carbon is formed, and, ultimately, failure.”

Your call of course but I’m not pushing the ZF past 220. Manually shifting also helps keep temps down.

 

[Slojo]

I don't want to have the engine constantly over 3k RPM. Too noisy for my classical music.

 

[BeardedYinzer]

I don't use manual mode too often and get around 11 or so towing my TJ, I have an Aliner (small camper) that I tow as well I'll get 14ish with that.

 

[Elff]

I pulled 6500lbs. from San Diego to Washington State. I kept the speed at 62mph. The 3.6 got 14 mpg. The squat was obvious but she drove straight and I never felt uncomfortable. I don't care to go 7650 in my max tow though.

Holy cow your rear end was squished.
I get 13MPG when I tow the TJ

@ShadowPapa
I put mine in ACC and do shift when I hit 3000-35000rpms on flats, but when I hit the hills, I rev the crap out of the engine to keep my speed up. If I start losing speed, I immediately down shift. For giggles next time, I am going to keep it 100% in auto mode and see how my Gas Mileage does.

 

[AmishMike]

Holy cow your rear end was squished.
I get 13MPG when I tow the TJ

@ShadowPapa
I put mine in ACC and do shift when I hit 3000-35000rpms on flats, but when I hit the hills, I rev the crap out of the engine to keep my speed up. If I start losing speed, I immediately down shift. For giggles next time, I am going to keep it 100% in auto mode and see how my Gas Mileage does.

It didn’t take long for me to realize that this wasn’t my 460 pulling, so just let it rev. Get ready for 10 mpg in auto mode. Wait until you see 3rd or 4th gear at 65 mph.
@XJADDICTION I don’t like higher trans temps either but 170-220 doesn’t seem realistic when you have an incorporated trans cooler and your coolant wants to be at 210.
Running a fleet of buses with automatics has made me look into trans temps. Some of them run constantly around 250 under normal operating conditions.

 

[Bonanza]

I guess no one really understands modern engines...........
It's not doing the engine any favors to try to keep it 2500 or less. In fact you are in low-lift mode where it makes the LEAST power.
3,000 RPM is nothing. Heck, that used to be the normal highway speed for a typical engine and now people freak out over 3,000 RPM in an engine with superior bearings, superior balance, superior everything for that matter.
The only reason to shift manually, as the manual says, is to reduce hunting - constant shifting by the transmission. The constant up and down, up and down, causes heat and wear.
But for our territory around here, I've found almost no difference at all in mpg shifting manually vs. automatic. I only ever use automatic to keep the RPM UP as specified in the book and to prevent hunting in our hills. It's really hilly here.
Towing I actually found better mpg with it shifting itself - until or unless it started to hunt and dropped the RPM too low.
Sub-3,000 rpm is actually not a friend of engines under a load.
But the non-mechanics will argue that they think the engine is better off at lower RPM. Sorry, it's not. In fact, the Chevy guys told me directly "let 'er rip" - it needs the higher RPM.
For one thing - better oiling of the engine, higher oil pressure moving oil through more quickly keeping the oil and the parts cool. If you let it run slow the oil is under more pressure and stress.
But the non-mechanics win, I guess, over science.

Quoting as this is spot on. The pentastar was designed with high RPMs in mind. I think the chief engineer was quoted as saying you should give these proper WOT runs on every drive for oil flow.

 

[JT1219]

Quoting as this is spot on. The pentastar was designed with high RPMs in mind. I think the chief engineer was quoted as saying you should give these proper WOT runs on every drive for oil flow.

The oil pressure certainly is good at higher rpms, usually it said around 79psi

 

[MaysvilleStig]

Normal operating temp for the ZF is 194, 220 in nowhere near stressful. What you strive for personally is up to you I guess.

 

[Gren71]

Quoting as this is spot on. The pentastar was designed with high RPMs in mind. I think the chief engineer was quoted as saying you should give these proper WOT runs on every drive for oil flow.

That just seems like such a complete and total disconnect from the target user. We all have a different idea of what is “normal driving” but id like to think most folks to WOT their Jt every day.
Is that something we’re all missing or more of a tongue and cheek comment from the designer

 

[Bonanza]

That just seems like such a complete and total disconnect from the target user. We all have a different idea of what is “normal driving” but id like to think most folks to WOT their Jt every day.
Is that something we’re all missing or more of a tongue and cheek comment from the designer

Take this with a HUGE grain of salt, but I remember reading this back when I had a 2013 two door JK:

(copy/pasted from a forum discussing which oil to use)

As an former Pentastar design engineer I am slightly bias but the engine is really high quality. Few points from the development using tens of millions of dollars in analysis and testing regarding the oil and durability..... The lighter oil was chosen mostly for fuel economy BUT engineering is the science of compromise. You help one thing but hurt another. A thicker oil will reduce timing chain and tensioner wear because the center timing chain idler doesn't go fully hydrodynamic till about 1650rpm on 5w-20. So, a thicker oil will lower that number slightly and with general loads/speeds the engine spends a lot of time around 1500-1750 rpm with the 8 speed. So thicker oil is a win there. Additionally, the earlier engines had what was called the "McDonald's Arches" in the idler bearing which was intended in making a more uniform distribution but in actuality acted as a knife edge. This design was changed around 2014 to a smooth bearing. So overall timing chain issues will likely follow the 2011-2014 engine years more than 2014+. Where you lose.... The head is very complicated with a Type II valve train. Meaning lots of things to pressurize and pump up at start up. A thicker oil didn't do so well here (on long sit times +cold start) and contributed to a overall increased engine wear especially in the head and cam bearings. Last point. This engine needs occasional WOT runs if you want it to last. Granny cycling is bad for it. So bad for it we actually created a new granny cycle test during the cylinder #3 misfire issue. The highest wear is in the valve guides, because of tight valve stem seals (for emissions, reduce oil burn). They basically dry out. When you go WOT/high rpm/load you get some fresh oil in there and this keeps the wear down. Thicker oil might not help this condition but we also change the valves/guides/seals in 2014+. Not sure the impact. Cheers! Kevin PS. Turn off stop start and do not run e85 if you are concerned about engine wear. Eats the engine alive.

 

[Gren71]

Take this with a HUGE grain of salt, but I remember reading this back when I had a 2013 two door JK:

(copy/pasted from a forum discussing which oil to use)

As an former Pentastar design engineer I am slightly bias but the engine is really high quality. Few points from the development using tens of millions of dollars in analysis and testing regarding the oil and durability..... The lighter oil was chosen mostly for fuel economy BUT engineering is the science of compromise. You help one thing but hurt another. A thicker oil will reduce timing chain and tensioner wear because the center timing chain idler doesn't go fully hydrodynamic till about 1650rpm on 5w-20. So, a thicker oil will lower that number slightly and with general loads/speeds the engine spends a lot of time around 1500-1750 rpm with the 8 speed. So thicker oil is a win there. Additionally, the earlier engines had what was called the "McDonald's Arches" in the idler bearing which was intended in making a more uniform distribution but in actuality acted as a knife edge. This design was changed around 2014 to a smooth bearing. So overall timing chain issues will likely follow the 2011-2014 engine years more than 2014+. Where you lose.... The head is very complicated with a Type II valve train. Meaning lots of things to pressurize and pump up at start up. A thicker oil didn't do so well here (on long sit times +cold start) and contributed to a overall increased engine wear especially in the head and cam bearings. Last point. This engine needs occasional WOT runs if you want it to last. Granny cycling is bad for it. So bad for it we actually created a new granny cycle test during the cylinder #3 misfire issue. The highest wear is in the valve guides, because of tight valve stem seals (for emissions, reduce oil burn). They basically dry out. When you go WOT/high rpm/load you get some fresh oil in there and this keeps the wear down. Thicker oil might not help this condition but we also change the valves/guides/seals in 2014+. Not sure the impact. Cheers! Kevin PS. Turn off stop start and do not run e85 if you are concerned about engine wear. Eats the engine alive.

Wow, had no idea. Thanks!

seems like we would be achieving the same effect while towing since we are running higher RPM. Adds points to @ShadowsPapa ‘s point.

 

[ShadowsPapa]

Wow, had no idea. Thanks!

seems like we would be achieving the same effect while towing since we are running higher RPM. Adds points to @ShadowsPapa ‘s point.

The valve stems are the only place where running it hard make any sense at all. All other areas are continuously oiled either through direct oil supply - pressure or through splash.
Wrist pins get splash from the spinning crank shaft- oil is tossed at the bottoms of the pistons. In some cases, and I have NOT looked at these specific pistons as far as design, but in SOME cases, oil gets to the wrist pins when the rings scrape oil off the cylinder wall on the down stroke - the oil gets behind the rings and goes through a channel and through a hole that leads to the wrist pin area.
Followers, cams, that sort of thing - all pressure-fed so no need for speed. You could idle the thing all day and those parts will get plenty of oil.
But oil to the valves varies with the engine - likely these are sealed well (auto makers have used positive type valve seals for longer than many members have been alive).
What we used to do is knurl the guides and that trapped oil in the guide, holding it there to lube the valve stem and the oil also helped cool the valve stem. Likely a no-no these days as oil pulled in past the valve stem goes out the cats - and can lead to carbon build-up, detonation and so on. So I could believe the valve part of that.
HOWEVER, that's an older description of an earlier version of these engines.
Many things changed - a lot of change, after his comments and after his stint there. It's not the same engine in so many ways it's silly.
Valve stems were shortened, the low lift means there's not as much friction, they don't move as far for each cycle unless you go higher RPM. So they helped mitigate valve stem wear by keeping the valve stem travel shorter.

E85 is only a problem if you stick with the extended oil change interval. Anyone planning on using E85 through a custom tune would need to revert back to the 1950s thinking - 3,000-4,000 mile oil changes. Otherwise, E85 isn't damaging to the engine itself. It's the byproducts of combustion that get into the crank case.

In short - a lot of that is old, for prior engine designs.

 

[KVJ]

What does WOT mean?

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