Is it bad to run your truck in “Auto 4wd”?

[aha1987]

Curious to know if any of you always keep your truck in 4wd auto. If so, does it hurt andything and does it effect MPG?

[Controller23]

Anecdotal, but I had a 2015 that stayed in auto 4wd. It however was owned by my work so I wasn’t afraid to beat it up, and I didn’t track mileage at all. Never had any problems with the truck though.


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[UGADawgs]

I think 4 auto keeps the transfer case in open diff mode, so it should be safe. However, if you're on dry pavement, not sure the value doing it. Mostly some mpg loss. If it was raining, I'd definitely use it.

[OnTheReel]

4 AUTO engages the front axles but sends very little power to the front wheels until slip is detected. The power distribution is handled by an electronic clutch in the transfer case.

 

In auto, there is a slight fuel economy penalty and also more noise / vibration, both due to having the axles engaged and more rolling resistance.

 

Also, in theory, driving all the time in 4 AUTO would increase wear on the transfer case clutch and assorted components.

 

Although it is “safe” to use all the time, you really should be in 2WD unless the road conditions are sloppy. I usually use 4A if there’s been a snowfall in the last couple days and the roads and parking lots aren’t all the way cleaned up. I also have been known to slip it into 4A if I feel like the guy next to me wants to have a little stoplight race. Otherwise it’s 2H basically all the time.

[Wiggums]

I read that it MPG drops by one if it's kept on Auto 4x4. Not bad for it but if you have unpredictable traction, better to keep it on.

[Booger T]

6 minutes ago, Wiggums said:

 

I read that it MPG drops by one if it's kept on Auto 4x4

 

Says who?

[Wiggums]

10 minutes ago, Booger T said:

Says who?

Manual states slight drop in gas mileage if set on auto instead of rear wheel drive.

 

 

[Imcrazy]

There is no good reason to do it... It will cause additional wear on the four wheel drive system.. Are you new to 4x4 trucks? If you have a locking rear end and you're not off road, there will be very few situations outside of snow that you use anything but 2 high... I will use AUTO if I am trying to get a jump on traffic off the line sometimes because the truck is quicker off the line with it but, beyond that unless there is significant snow on the road there aren't many reasons I can think of that any 4 wheel drive mode is needed if you're on paved roads..

[diyer2]

37 minutes ago, Imcrazy said:

There is no good reason to do it... It will cause additional wear on the four wheel drive system.. Are you new to 4x4 trucks? If you have a locking rear end and you're not off road, there will be very few situations outside of snow that you use anything but 2 high... I will use AUTO if I am trying to get a jump on traffic off the line sometimes because the truck is quicker off the line with it but, beyond that unless there is significant snow on the road there aren't many reasons I can think of that any 4 wheel drive mode is needed if you're on paved roads..

Agree.

 

[Druder]

I've accidentally left my truck in auto the day after a snowstorm and didn't notice a difference in driving characteristics but like everyone else said, there's no benefit to it, only cons unless it's raining or snowing.

[aha1987]

1 hour ago, Imcrazy said:

There is no good reason to do it... It will cause additional wear on the four wheel drive system.. Are you new to 4x4 trucks? If you have a locking rear end and you're not off road, there will be very few situations outside of snow that you use anything but 2 high... I will use AUTO if I am trying to get a jump on traffic off the line sometimes because the truck is quicker off the line with it but, beyond that unless there is significant snow on the road there aren't many reasons I can think of that any 4 wheel drive mode is needed if you're on paved roads..

Am I new to 4X4? That is a no. I’ve owned more than I can count. Btw, your rear end isn’t locked when you are in auto 4WD. It locks when it senses slipping. Will do the same thing in 2WD

[Imcrazy]

3 hours ago, Aycock1987 said:

Am I new to 4X4? That is a no. I’ve owned more than I can count. Btw, your rear end isn’t locked when you are in auto 4WD. It locks when it senses slipping. Will do the same thing in 2WD

Yes I knew that about the G80 rear end... The auto mode is really only intended for mixed road conditions, IE partially snow covered roads and getting in and out of slushy parking lots or messy gravel roads. If you leave the truck in auto for a few days accidentally I'm sure you'll be just fine but, there is not really any reason to use auto unless you're off road or the road conditions are poor..

[Cpl_Punishment]

I agree with the folks who recommend running in 2H unless traction is bad. However, when I'm driving my company's trucks around the plant where I work, I find it will spin a little on the sand and gravel that's all over our roads so I usually shift to 4A so our safety guys don't give me shit. 

[UGADawgs]

1 hour ago, Cpl_Punishment said:

I agree with the folks who recommend running in 2H unless traction is bad. However, when I'm driving my company's trucks around the plant where I work, I find it will spin a little on the sand and gravel that's all over our roads so I usually shift to 4A so our safety guys don't give me shit. 

Sand and gravel, yes ?

Clean pavement, no ?

Edited March 24, 2019 by UGADawgs

[z1boss]

On 3/23/2019 at 7:52 PM, Aycock1987 said:

Curious to know if any of you always keep your truck in 4wd auto. If so, does it hurt andything and does it effect MPG?

I've always ran my trucks in 4wd auto.  No issues at all.  I've noticed that the gas mileage isnt really affected either based on my testing.