New used ZR-2, lockers not Working, bad Fuel Mileage.

[GoHack]

Hi everyone,

I just bought a used 2025 Colorado ZR-2 w/just 3200 miles yesterday.
She's in mint condition w/o a scratch and the original owner traded her in due to wanting a bigger truck, which he bought.

I went and christened her offroad yesterday, testing everything doing so w/the only major issue being the Front and Rear lockers not staying locked.

The transfer case worked OK, both switching into 4Hi while driving or at a complete stop, and 4 Lo, switching it at a complete stop w/the transmission in Neutral.

Next comes the Lockers, when I went and switched the Rear Locker in at 4Hi, while moving slowly, the indicator would show it locked in, sometimes taking a few seconds to do so, and for a short period of time driving, worked, but then all of a sudden, it would kick back out into 2Hi. Tried it either at a complete stop, and while slowly moving. Tried it several times, no changes there.

Next with the Front and Rear Lockers in 4Lo, it would Lock in after the indicator light flashed a few times, but not too soon after, while driving, either switch into the Rear Locker only, and then back into unlocked there entirely.
One time going downhill on some slippery gravel, it worked for a while, but not too soon afterwards, kick back out into unlocked.
Anything that I'm doing wrong here? I'm getting no error indicators if there are any to be shown.

Then there was the highway fuel mileage.
Driving on the highway w/my speed set at 70 mph in cruise, the mileage varied from a low of 13 mpg to a high of 18. It was windy, where it seemed run at 13 mpg, but once the wind died down, I got a high of 18.
From my research, I thought the ZR-2 got a high of 20 Highway. Once again, the truck has only 3200 miles on the engine, if that's broken in enough.
I don't know what engine oil was installed by the dealer.
I was running 91 Octane fuel, Chevron my preference.

Thanks

 

[GoHack]

I just read that it might be in the switch itself in that you need to press it hard for it for it to fully engage?

 

[MO_ZR2]

Congrats on the new ride. I bought my daughter a ‘24 and drive it occasionally and appreciate the truck more every time I do - I think her lifetime average is 17 mpg - your truck sounds like it’s getting what I would expect (given the wind and other factors) and could increase just a bit as it continues to break in.

 

[GoHack]

I just read in the online owner's manual:
"The locking rear axle will be disengaged when the vehicle speed exceeds 30 km/h (20 mph).
The Off-Road Mode allows the axle lock to remain engaged at higher vehicle speeds"

I wasn't in Off-Road Mode.

Boy I hate electronics.
I miss the good ole days of things being all manual.

 

[GoHack]

Tested it in Off-Road Mode Monday and it now works.
Once again, I hate electronics. I miss the good ole manual transfer case shifter and locking hubs. I guess in this day and age, people can't operate such hardware.
The only other issue left, for me, is the high fuel mileage.
Studying the issue closer, the Window Sticker, which wasn't available at the time I purchased, since the vehicle was used, shows 17 local/17 Highway, so I guess what I'm getting is correct, though I will try to improve it using good FULL Synthetic Engine oil, like Amsoil, and eventually maybe getting less aggressive tires.

With the oil, I've already had an issue at the dealer I bought the truck at, telling me they would not install my own provided oil (Amsoil) in what is my truck. It has to be a GM approved oil.
Amsoil already exceeds GM's specifications, but doesn't want to pay GM for its official approval.

Other than that, she drives beautifully, especially offroad, thanks to those shocks I would imagine.

I've started buying some items for the truck, like a rubber bed mat, a window sun shield, and definitely need to order some steps for the doors. I need to really step up in order to get into the cab.
Maybe eventually a winch setup. I've certainly had my experiences of getting stuck offroad in the past.

 

[MO_ZR2]

Tested it in Off-Road Mode Monday and it now works.
Once again, I hate electronics. I miss the good ole manual transfer case shifter and locking hubs. I guess in this day and age, people can't operate such hardware.
The only other issue left, for me, is the high fuel mileage.
Studying the issue closer, the Window Sticker, which wasn't available at the time I purchased, since the vehicle was used, shows 17 local/17 Highway, so I guess what I'm getting is correct, though I will try to improve it using good FULL Synthetic Engine oil, like Amsoil, and eventually maybe getting less aggressive tires.

With the oil, I've already had an issue at the dealer I bought the truck at, telling me they would not install my own provided oil (Amsoil) in what is my truck. It has to be a GM approved oil.
Amsoil already exceeds GM's specifications, but doesn't want to pay GM for its official approval.

Other than that, she drives beautifully, especially offroad, thanks to those shocks I would imagine.

I've started buying some items for the truck, like a rubber bed mat, a window sun shield, and definitely need to order some steps for the doors. I need to really step up in order to get into the cab.
Maybe eventually a winch setup. I've certainly had my experiences of getting stuck offroad in the past.

Yep - your mileage is as expected

 

[AXE]

These ZR2 trucks are easy to change oil. There is plenty of clearance to get underneath. The drain bolt is perfectly positioned and the filter is too. Probably the easiest oll changes I've ever done. you can save a lotnof money and do it in about 30 minutes.

 

[GoHack]

Yep - your mileage is as expected

Meaning what?

 

[MO_ZR2]

Meaning what?

Meaning you said…

Then there was the highway fuel mileage.
Driving on the highway w/my speed set at 70 mph in cruise, the mileage varied from a low of 13 mpg to a high of 18. It was windy, where it seemed run at 13 mpg, but once the wind died down, I got a high of 18.
From my research, I thought the ZR-2 got a high of 20 Highway. Once again, the truck has only 3200 miles on the engine, if that's broken in enough.

And a couple of us responded that seemed like it was in line with our experience and what the Colorado zr2 is rated. Which is 17/17 - pushing into a head wind it’s not going to get 17, wind dies down and you got 18. If memory serves one of the other trims might be rated for 20 on highway which might be where that number came from.

“studying the issue closer” - I was ultimately meaning you don’t have an issue, it’s what you should expect for a Colorado in zr2 trim.

 

[MNNJR69]

Hi everyone,

I just bought a used 2025 Colorado ZR-2 w/just 3200 miles yesterday.
She's in mint condition w/o a scratch and the original owner traded her in due to wanting a bigger truck, which he bought.

I went and christened her offroad yesterday, testing everything doing so w/the only major issue being the Front and Rear lockers not staying locked.

The transfer case worked OK, both switching into 4Hi while driving or at a complete stop, and 4 Lo, switching it at a complete stop w/the transmission in Neutral.

Next comes the Lockers, when I went and switched the Rear Locker in at 4Hi, while moving slowly, the indicator would show it locked in, sometimes taking a few seconds to do so, and for a short period of time driving, worked, but then all of a sudden, it would kick back out into 2Hi. Tried it either at a complete stop, and while slowly moving. Tried it several times, no changes there.

Next with the Front and Rear Lockers in 4Lo, it would Lock in after the indicator light flashed a few times, but not too soon after, while driving, either switch into the Rear Locker only, and then back into unlocked there entirely.
One time going downhill on some slippery gravel, it worked for a while, but not too soon afterwards, kick back out into unlocked.
Anything that I'm doing wrong here? I'm getting no error indicators if there are any to be shown.

Then there was the highway fuel mileage.
Driving on the highway w/my speed set at 70 mph in cruise, the mileage varied from a low of 13 mpg to a high of 18. It was windy, where it seemed run at 13 mpg, but once the wind died down, I got a high of 18.
From my research, I thought the ZR-2 got a high of 20 Highway. Once again, the truck has only 3200 miles on the engine, if that's broken in enough.
I don't know what engine oil was installed by the dealer.
I was running 91 Octane fuel, Chevron my preference.

Thanks


View attachment 27231

Congrats on your new truck,!
I find that doing anything with lockers You have to put it in neutral.... Till the liight goes solid... Never had an issue doing it that way

 

[MNNJR69]

I also found that if you hold your lockers down it will automatically turn your traction control and ESC off

 

[Busa Dave]

Meaning you said…

Then there was the highway fuel mileage.
Driving on the highway w/my speed set at 70 mph in cruise, the mileage varied from a low of 13 mpg to a high of 18. It was windy, where it seemed run at 13 mpg, but once the wind died down, I got a high of 18.
From my research, I thought the ZR-2 got a high of 20 Highway. Once again, the truck has only 3200 miles on the engine, if that's broken in enough.

And a couple of us responded that seemed like it was in line with our experience and what the Colorado zr2 is rated. Which is 17/17 - pushing into a head wind it’s not going to get 17, wind dies down and you got 18. If memory serves one of the other trims might be rated for 20 on highway which might be where that number came from.

“studying the issue closer” - I was ultimately meaning you don’t have an issue, it’s what you should expect for a Colorado in zr2 trim.

Mine (2024 Bison) regularly gets a little over 20mpg on the highway regularly with no headwinds. I also run Goodyear Boulder MT's 35x12.50-17 tires. I use Amsoil signature oil and run 55 psi in the tires. It can be done. Just a note that makes about a 1 to 2 mpg difference (especially highway) is I run 90 octane (yes know 87 is all that is required and recommended) because it is the only way I can get ethanol free unleaded here in the DFW area.

 

[MO_ZR2]

Mine (2024 Bison) regularly gets a little over 20mpg on the highway regularly with no headwinds. I also run Goodyear Boulder MT's 35x12.50-17 tires. I use Amsoil signature oil and run 55 psi in the tires. It can be done. Just a note that makes about a 1 to 2 mpg difference (especially highway) is I run 90 octane (yes know 87 is all that is required and recommended) because it is the only way I can get ethanol free unleaded here in the DFW area.

Im sure it can be done. I certainly am not trying to start a debate either. The title of the thread says “bad fuel mileage” and sounded to me like the OP was worried his truck may have an “issue” - I was simply pointing out that it’s rated for 17/17 and if he was getting 18 with no wind, it didn’t sound to me like his new truck had an “issue” that was impacting his mileage. That’s not “bad mileage”, that’s essentially what the truck is rated to get. The old adage of “your mileage may vary” applies, but buying one and expecting to get low to mid-twenties isn’t realistic. If one can use higher dollar oil and more expensive fuel to eek out 1-2 MPG, may be worth it

 

[Busa Dave]

Im sure it can be done. I certainly am not trying to start a debate either. The title of the thread says “bad fuel mileage” and sounded to me like the OP was worried his truck may have an “issue” - I was simply pointing out that it’s rated for 17 and if he was getting 18 with no wind, it didn’t sound to me like his new truck had an “issue” that was impacting his mileage. That’s not “bad mileage”, that’s essentially what the truck is rated to get. If one can use higher dollar oil and more expensive fuel to eek out 1-2 MPG, may be worth it

The issue for me is not fuel mileage per se it is the ability to use ethanol free fuel. The tires I run are heavier and just a little larger but much more aggressive. Would guess that if I still had the factory rubber on it would be a little better still, this truck gets around like a goat off road.

 

[MO_ZR2]

The issue for me is not fuel mileage per se it is the ability to use ethanol free fuel. The tires I run are heavier and just a little larger but much more aggressive. Would guess that if I still had the factory rubber on it would be a little better still, this truck gets around like a goat off road.

You’ve got a keeper

 

[GoHack]

I did well over 1000 miles this holiday weekend, driving both dirt and highway.

Before leaving, on Friday I first had my tires rotated and checked balanced and was told that a couple of the tires were a little off.

I then put a brand-new clean air filter in as well, since the one in it was 80% good according to the computer data system in the truck.

Leaving in the early morning on Saturday, I went and filled up w/Chevron 91 octane.
My odometer was just under 4000 miles.

Driving on a flat highway w/my Cruise set at 70, Rt 14 into 395 in Eastern California, I broke a high of 23 mpg, w/an average of between 21 to 22, w/no wind.
I was very happy w/that for sure.

During the day it did drop down to the mid-twenties (20.5), probably due to a little wind.

I did around 600 miles, highway that day, and off course when I hit the real hilly sections, like outside of Bishop, my mileage dropped down to around 19 if I recall, if not lower, as was expected.

Sunday, I drove to a place called Kennedy Meadow, or should I say, drove up to.
Driving there in back roads in the mountains, if you know the area, the roads were paved but w/lots of potholes sadly, enjoying the mountains and scenery in the backcountry, w/very few people surprisingly camping.

I did do some off-roading, on a fairly rough dirt road for a while, w/no issues w/any rub or contact underneath, but after a few miles, and being by myself, I figured I'd better turn around.
It drove great w/no issues there.
Sadly too, there were also dirt bikers there, which got me a little nervous w/them around.

I then drove from the Kennedy Meadows down to the Kern River Valley, Lake Issabella.
The road there was on an unmaintained porthole ridden paved road. The country was beautiful, w/very few people seen along the way.
Driving probably in the 30-mph range, taking my time and enjoying the country, I average around 23 - 24 mpg, breaking 25 going downhill.

Arriving down the Kern River, where I expected lots of campers there along the river, but there weren't as many as I saw last Labor Day weekend, the last time I was there.

The truck reached its last hurdle w/the fuel mileage w/me.

The truck now has some 4940 miles on it, and I'm scheduled for an oil/filter change on Friday, where it should be at a little over 5000 miles.
The engine should be more than broken in now that I plan to put 5W-30 Amsoil Full Synthetic oil in it.
At first the Service Manager at the dealer wouldn't allow anything but a GM oil, which I wasn't at all too happy with, since I never had others say anything about my using Amsoil on other brands of vehicles, but when I came back for another reason, the Service Manager said that it was OK to use the Amsoil, I guess he had talked w/someone, which I was very pleased about, but I still have to use their OEM oil filter, in place of my Wix XP Filter which I had already bought. I may simply crawl under after, when the engine is cold, and switch filters, and replace any missing oil left in the filter.
I do my research and I prefer to use the very best when maintaining my vehicles, always have. I also use to do my own work and service, but I'm getting a little too old now for that.

The truck is all dirty, as expected, w/a little mud from a small mud hole I drove through, and so I need to wash her today. I did want to drive a day or two to show people what a true 4x4 should look like being all dirty and such, but I'm getting a Chevy Rubber bed matt for my truck bed that I ordered, which is due in tomorrow, so I want the bed clean.
Sadly, more than often, people buy these kinds of vehicles for the looks, put huge lifts on them together w/oversized tires, "ALL" strictly for the looks, and never once ever getting them dirty.
Sadly, these are the kinds of people that are today's generation of customers, and so the truck manufacture's design the trucks for these kinds of customers, making the trucks as dummy proof as possible.
I've even seen Jeep Wranglers that have been lowered, w/Huge chrome street tires.

 

[AXE]

I wouldn't sweat the oil and filter change from the dealer. The oil and filter will be more than adequate.

I changed approximately 15 gallons of oil this past week on two skid steers, a 125kW diesel generator, a 2500HD Duramax, and a motorcycle. I used Rotella T6, Rotella T4, Mobil Delvac Extreme, and Honda oil. I used Wix, Bobcat, Napa, and Mobil 1 filters. Never once did I think about what was used, cause I know they are all quality products.

 

[Busa Dave]

Just got back from a trip to Fort Worth some highway mostly slower about 50 miles round trip. This was taken when I got to my destination in Fort Worth. Made it to 22.9 before I got home. The 90-octane ethanol free fuel is awesome!!

 

[GoHack]

Just got back from a trip to Fort Worth some highway mostly slower about 50 miles round trip. This was taken when I got to my destination in Fort Worth. Made it to 22.9 before I got home. The 90-octane ethanol free fuel is awesome!!
View attachment 27282

Surprisingly, here in California where I presently live ️, they don't use Ethanol in their fuels, neither does Oregon, which surprised me.
Coming from Washington state, that's all they use in their fuels there now-a-days.
When I first moved down here to California, while driving here, I started to notice my vehicle feeling different. It seem to be a little more powerful. Thinking about it, I started to wonder if it was due to a lack of Ethanol in the fuel. I was in Oregon at the time. So the next time I stopped for fuel, I looked, and sure enough there wasn't any in the fuel in Oregon, and neither in California.
There definitely is a difference in performance between the two.
I guess that's one positive about California, which there aren't a whole lot of.

 

[GoHack]

Question: With the Ford 2.3L I4 engine, it's setup to run w/either regular 87 or high test 91+ fuel. With the High Test, the computer corrects for the fuel, adding more HP.
With Regular 87, the HP is said to be around 270, while w/91+, it's 300+ HP.

The GM 2.7 I4 is said to be 310 HP, but is that w/just Regular 87?
If it is, then using 91+, does the HP increase using it?