4 wheel drive "Auto" setting

bertiman · December 29, 2015

Hi Folks!

Besides reduced gas milage, are there any issues with keeping my 2015 5.3l Silverado in the 4 wheel drive "auto" setting full time (well, at least for the winter). The manual warns against 4h & 4l in dry conditions but does not make such a warning for the auto setting. I've searched the forums and there doesn't seem to be clear consensus in the threads I've read..... so I figured I'd ask. I don't want to damage anything or cause stuff to prematurely wear.

Thanks!

robvas · December 29, 2015

Lots of people do it. No issues.

Doobs41378 · December 29, 2015

Yes, I agree. No issues. I turn mine to auto for winter and off for the summer.

crushNchowda · December 29, 2015

The only problems I run into leaving in 4wd auto is when the pavement is a Mix of dry salt crusted patches, hard packed snow patches, and ice patches- once in a great while the 4wd unto will kick in (usually as I'm turning) and I'll have one of the 2 front wheels on slippery stuff while the other is on dry and it feels like it's binding or just not doing anything good for the truck so to speak

Other than that ok to leave it on, I leave it on in heavy rain in the summer/fall too.

I've also driven 4 hrs home @ 70mph in 4wdhi in 4-8" of snow on the highway and in blizzard like conditions (running studded snows) so I may not be the best person to ask either hahaa

Tiger_993 · December 29, 2015

You'll get slightly more drivetrain noise and the clutch pack in the transfer case may experience additional wear since the transfer case is partially engaged when the AUTO setting is used. If I'm on dry pavement, my truck is in 2WD always. I like the way it drives and responds a little better in 2WD than in AUTO.

bertiman · December 30, 2015

You'll get slightly more drivetrain noise and the clutch pack in the transfer case may experience additional wear since the transfer case is partially engaged when the AUTO setting is used. If I'm on dry pavement, my truck is in 2WD always. I like the way it drives and responds a little better in 2WD than in AUTO.

This is one of my concerns... Will the additional wear on the clutch pack have an appreciable effect on its functional lifespan?

redwngr · December 30, 2015

I never use auto.

Like to know whether it's in or out.

SkiDooNick700 · December 30, 2015

Unless that pavement is bone dry, Put that thing in auto and forget about it.

Like someone else mentioned though, I don't like turning in a parking lot with Auto or even 4wd for that matter, unless there are a few inches of snow minimum.

Tiger_993 · December 30, 2015

This is one of my concerns... Will the additional wear on the clutch pack have an appreciable effect on its functional lifespan?

My guess is that any additional wear won't be significant enough to cause concern. That being said, you could render the issue moot by simply switching between 2WD and auto as needed.

SMiller · December 30, 2015

Auto is made to be ran the life of the truck, there are some that put it in auto and never touch it and that's perfectly fine, others like myself are anal and must run 2wd. You will loose slight mileage running auto but having the front somewhat engaged is no problem.

joshc64311 · December 30, 2015

I drove almost 600 miles at highway speed in AWD back in august, seems fine and still works fine for me.

hurricanoday · December 30, 2015

I live in seattle and have been putting it in auto when it rains or icy conditions. I even put it in auto when pulling my boat out of the water. Also haven't really noticed a drop in mpgs, can anyone confirm that auto hurts your mileage or are people just assuming that? Just went on a roundtrip about 200 miles north to visit family and was in auto the whole time. Went through the mcds drive though and parking lots. No problem in auto and wasn't even raining. People making it sound like auto or 4wd will ruin your truck unless you are climbing Mount Everest.

Basically have never put it in 4wd, just auto for anytime I think I might need it. Even forgot it was in auto plenty of times. Haven't noticed anything happening or any more noise, but I'm no expert. I drive the truck it doesn't drive me

crushNchowda · December 30, 2015

I live in seattle and have been putting it in auto when it rains or icy conditions. I even put it in auto when pulling my boat out of the water. Also haven't really noticed a drop in mpgs, can anyone confirm that auto hurts your mileage or are people just assuming that? Just went on a roundtrip about 200 miles north to visit family and was in auto the whole time. Went through the mcds drive though and parking lots. No problem in auto and wasn't even raining. People making it sound like auto or 4wd will ruin your truck unless you are climbing Mount Everest.

Basically have never put it in 4wd, just auto for anytime I think I might need it. Even forgot it was in auto plenty of times. Haven't noticed anything happening or any more noise, but I'm no expert. I drive the truck it doesn't drive me

it absolutely drops your MPG's - instantaneously, without a doubt, no question whatsoever. I lose about 1-1.5 mpg in general driving in 4WD auto vs. 2wd - even if the front wheels aren't turning, it is still passively engaging the front diff & causing greater parasitic loss therefore chugging more fuel. A perfect analogy would be same exact car but auto vs. manual - if the gearing is the same and all else is equal no matter what the auto sucks more gas since there's an additional rotating part involved. It absolutely makes a noise too - they all do when in any of the 3 4WD modes - you may not have the ears to hear it, but there is sound reminiscent of an old " CD ROM" drive spinning or some electrical interference emitting from the dash around where the knob is.

It will also obviously increase wear on the clutch pack and front differential - whenever you use a part more than normal it'll wear more quickly - that's common sense. I would definitely not just put it in auto 4 and "forget about it" - no way. To each his own....but I mean, use common sense.

I'm not saying its "bad" for the truck, but I sure as hell wouldn't try to argue it WON'T decrease the life of the drivetrain & components or hurt your MPG's - common sense will tell you the opposite,

hurricanoday · December 30, 2015

\it absolutely drops your MPG's - instantaneously, without a doubt, no question whatsoever. I lose about 1-1.5 mpg in general driving in 4WD auto vs. 2wd - even if the front wheels aren't turning, it is still passively engaging the front diff & causing greater parasitic loss therefore chugging more fuel. A perfect analogy would be same exact car but auto vs. manual - if the gearing is the same and all else is equal no matter what the auto sucks more gas since there's an additional rotating part involved. It absolutely makes a noise too - they all do when in any of the 3 4WD modes - you may not have the ears to hear it, but there is sound reminiscent of an old " CD ROM" drive spinning or some electrical interference emitting from the dash around where the knob is.

It will also obviously increase wear on the clutch pack and front differential - whenever you use a part more than normal it'll wear more quickly - that's common sense. I would definitely not just put it in auto 4 and "forget about it" - no way. To each his own....but I mean, use common sense.

I'm not saying its "bad" for the truck, but I sure as hell wouldn't try to argue it WON'T decrease the life of the drivetrain & components or hurt your MPG's - common sense will tell you the opposite,

um I think you misunderstood what I was trying to say or maybe I didn't express what I was saying correctly. I have no doubt that trying to move 4 wheels vs 2 will lower your mpgs, but by how much is what I meant. I also stated from my experience that I haven't noticed a drop in mpg while in 4auto, but I also didn't run exact scientific tests and measure my gas. An example is I put 22s on my truck and every "expert" on this forums said it will lower the mileage and mess up the speedo. While it does but in real life scenarios it doesn't, meaning yes my speedo is off by .2 or what ever and I might get 21.7 vs 21.9 (who knows) but I am still getting 20+ mpg on the hwy and averaging what gm is saying 17+ for the lifetime of the truck. So you are saying 1+ mpg and I haven't noticed that maybe because I'm wrong or maybe it is because being in "auto" isn't as significant as some people on these forums make it out to be. As I posted about my experiences and 1mpg could easily be just driving habits, trips, terrain etc.

As for the "drivetrain and components" I assume putting it in auto is how it was designed and doesn't use it more than normal. If we are going to use this "common sense" then why even start the engine because it will put wear and tear on everything inside the engine. So I ask who decides what is "normal" and why do you have to be climbing Mount Everest to be normal? Driving your truck in auto in the rain is normal or anytime the driver feels like it is needed is normal. Ie like the op asks in winter or other examples people have given.

I also stated that I have put it in auto (due to rain etc) and then have forgotten to take it back out. Not on purpose, meaning I forgot and everything has been fine with my truck. But you are correct, anytime you use something common sense will tell you that it could be hurting the life.

But still then I disagree if I drive my truck in auto while it is raining and then park for the night, wake up the next day and it isn't raining then drive for 10 miles only to look down in a panic realizing it is still in auto, the truck will be fine. I put my truck in auto every time I think I need it and in my opinion everyone else who spends their money on a truck should use the auto/4wd everytime they think they need it.