First Time Vehicle/truck Owner

BigZed · April 3, 2010

Hey guys,

I've owned my truck for about 4.5 months now and absolutely love it. It's the first vehicle I've ever owned so this would also be the first truck I have ever driven. Having said that I'm extremely inexperienced when it comes to operating and maintaining my vehicle. I have been trolling these forums for a few months and have picked up quite alot. However I do have some lingering issues that I need some advice with, mostly because of my inexperience.

My first concern is my tranny; It's the new 6 speed (compared to the 4 spd) and sometimes I feel like it does change gears rather hard. Now my concern is, since i'm inexperienced, i'm not sure what "hard" truly is. My natural reaction when it occurs is "that just doesnt seem right". I usually find it happens in the lower gears between 0 and 40 KPH. (0 to 24 mph) and when the truck is starting from a cold start (engine isnt warm as if its been sitting over night). I have read on this site that when the tranny warms up the gears switch more efficiently (correct me if im wrong please). I've also read on here that there have been past issues with this tranny, though I havent seen any reference to the 2010 build year. Since I've had the truck ive never had a warning light come on and each month the onstar email i receive says my truck is perfectly fine. So maybe this issue is just the way the truck handles naturally. Again referencing my inexperience.

My second concern is my driving habit. Now again from reading on this site this topic is very subjective as to how ppl like to drive their truck. I personally would classify myself as someone who nurses the gas pedal. Off a red light I would say I never go over 2000rpm even in first gear, sometimes I find the the tranny does hang at 1500rpm and then finally rolls over into the higher gear (thus giving me lower rpm). I try not to let it hang on a lower gear as I find a) its not a smooth ride b) doesnt feel natural for the truck to be driven like that. My main concern regarding this issue is; even though I nurse the pedal, does this style of driving ultimately lead to a lower efficiency in fuel consumption? I ask because leaving each gear hanging ultimately has the engine reving more then it should, at least I believe so. Should I be accelorating quicker through the gears so that when I'm at 50kph (30mph) the engine is purring at 1000rpm. Also I understand that I'm not going to get amazing gas mileage, its a truck I want the power and towing capacity, thats why I bought it!! I'm currently getting 16L/100km (14mpg) I find this is not that great considering what I've noticed on this site and other ppl posting thier fuel consumption. I'd say i'm 60/40 city/highway driving. The truck only has 3600km (2200 miles) on it so I'm not even sure if it's fully broken in yet. Any insight and advice would be great regarding this issue. I understand it can be subjective so try and keep in mind that I dont hammer the pedal down. I'm more concerned on the tranny hanging issue then the fuel consumption, but hey if i can save some fuel also that would be great also!!

My final concern is the 4x4, specifically the electronic transfer case. I usually keep mine on AUTO but since the summer is here I find that i rarely (if at all) use the 4x4. The only time I use it is when i'm pulling my boat out of the water. I use 4x4 HI for that as I have no need (not yet anyway) for 4x4 LOW. My question is, If I select 2x4 mode and keep it on that mode for a long period of time, lets say the entire summer, with only a half dozen times using 4x4, will the gears inside the transfer case degrade due to inactivity? I'm just picturing gears sitting idle for such a long time and then all of a sudden asked to engage, could this be a bad thing? OR should I just leave it on auto no matter what? I'm not sure exactly how AUTO works, I assume the gears arent engaged unless the truck feels it needs the extra front power.

Also when in AUTO but only using the rear tires, am I in a truly "2x4 state"? That is the SAME as selecting 2x4 mode?

Thanks for any info or insight on these few issues. Ive searched the forums and found a few topics that brush on my issues but considering im inexperienced maybe the answers I get will be "dumbed down" for a newbie truck owner!!!!!

PS: 2010 Sierra Ext Cab All Terrain Package Z71 4x4 black 5.3L 6spd. Yes I know pics will be added in a couple days.

amtz.zero · April 3, 2010

About your transmission- that sounds normal to me.

And the way you drive sounds fine to me too. I don't think you're wasting any extra gas like that. You waste more when you take off really fast from a stoplight. About the 4x4, I wouldn't know since I've never had one.

wurgs · April 3, 2010

Don't worry about the gears staying idle for any length time. Before the auto 4x4 everyone ran in 2wd mode till 4wd was needed with no issues. Someone correct me if I'm wrong but in auto mode there's no power going up front but everything is still engaged. Dealers will say its not an issue but I would think it would add to the wear of the components as well as affect gas mileage. I personally would just keep it in 2wd till 4wd is needed as its just a push of the button away

By the way, nice choice of truck. Mine is identical except a 09 6.0L

Daryl Z71 · April 3, 2010

I drive around in 2Hi. If I need 4wd I just push the button. I never use Auto.

2005LT · April 3, 2010

I never use Auto either but that's because of the "thunk" that would occur in my mom's 2002 Envoy. Never did like that. Apparantly it's a lot better in these trucks but we just haven't had the snow for me to confirm that.

Zach, that all sounds pretty normal to me. I personally find that my 6 speed "short shifts" and ends up bogging the engine a little too much but that's for fuel economy reasons I guess. As for the early morning shifting when cold, mine shifts a little harsh in the lower gears too depending on throttle position. That seems normal to me and I wouldn't worry about it.

The one thing I don't like is the harsh bang/thunk I get when shifting from P to D, or from R to D when everything is cold. Goes away once it warms up but I still worry about it. Does yours do that?

As for the mileage, if you've been running around in Auto 4wd in the cooler weather with an engine that's not broken in yet, 16L/100km sounds right on par to me. I've been getting ~18L/100km (~14 mpg) in the winter in 2wd with about the 50/50 city/highway mix that you have. Last summer I was getting about 15L/100km (~16 mpg). Enjoy the new truck and welcome to the site!

BigZed · April 3, 2010

The one thing I don't like is the harsh bang/thunk I get when shifting from P to D, or from R to D when everything is cold. Goes away once it warms up but I still worry about it. Does yours do that?

I do find that there is a loud bang/thunk when shifting into D or R from P. My driveway has a slight incline to it but I would say the incline is the same for any normal paved driveway. I believe I read in the manaul somewhere that when shifting out of P while on an incline you may experience the bang/thunk. I forget the proper term at the moment but there is strain on the parking prawl in the tranny from being in the incline position while on a slight grade. I know my definition isnt perfect but its something along those lines. I hope this is referring to your situation. When I'm at work on a flat grade I do not notice this issue. I guess I need to learn how to fully park properly so there isnt strain of the weight of the truck on the tranny.

Chevy Boy · April 3, 2010

Next time you park in your driveway engage the park brake pedal before you put in on park and then withour taking the park brake off try to put in on reverse or drive and see if you hear that noise again, if don't hear it then it's just the inclinasion in your driveway that does that......another thing you can try is try to park going forward into your driveway or the opposite goind backward into to it and see if your hear that noise one way or the other.

And for the auto 4x4 I would leave it on 2wd all the time and if you need 4x4 then use 4wd HI.....here in Canada after a snow storm I use auto 4x4 for a day or two depending on the road condition so that if the rear wheel start to spin the computer will engage the 4x4 automatically when needed.

Have fun with your new truck....!

ryan_hermanutz · April 3, 2010

I think that your fine how you drive your truck. It sounds like your tranny is just fine, and the way you gas from a start is probably better for your tranny than flooring it if you plan of trying to get 1,000,000 miles out of it. The 4x4 is pretty subjective. I leave mine in 2wd 99% of the time, I will put it in Auto when I know my rear wheels will spin like at a stop And I'm turning up a hill or something like that. You probably don't need to but it's good practice to put your truck in 4HI and 4LOW once a month just to make sure it still works. I usally do it in grass as to make sure I'm not binding any of the wheels. All in all I think your truck is fine and your doing it right.

BigZed · April 3, 2010

Thanks guys for the comments. I'm glad my tranny seems to be working fine. For awhile there i thought i had a lemon tranny. I guess I just have to get used to how a 6 spd handles (never mind the entire truck driving experience).

I'll try the 2wd only mode for a bit, maybe i'll even get better fuel mileage with just 2wd on. Time will tell.

jro909 · April 3, 2010

trans sounds normal, driving like an old lady is a good idea..saves wear and tear let alone fuel....as far as 4x4 just drive in 2 hi unless you need the 4x4...your theory is kind of odd, it would be like saying if i never used my radio it would fall out...as long you maintain the truck all will be good, i know people that use 4x4 maybe once a year and leave it in 2hi otherwise with zero issues...

caddycruiser · April 4, 2010

Thanks guys for the comments. I'm glad my tranny seems to be working fine. For awhile there i thought i had a lemon tranny. I guess I just have to get used to how a 6 spd handles (never mind the entire truck driving experience).

I'll try the 2wd only mode for a bit, maybe i'll even get better fuel mileage with just 2wd on. Time will tell.

Don't drive in Auto 4wd mode UNLESS you need it for a specific reason. You're just adding wear & tear to parts in normal driving that don't require the front wheels to be linked because the transfer case is engaged and it's not meant to be driven 24/7 like this. Only when needed, i.e. it's winter and the roads are questionable, etc. NOT everyday.

Same discussion came up on the Avalanche board. From that, a great post from a GM tech and then a copy/paste of a GM technical bulletin specifically about issues related to driving in Auto all the time:

The other reason for using auto or 4hi ONLY when conditions warrant is that the transfer case IS engaged in 4wd and is not designed to be driven 24\7 (unless conditions warrant) in 4wd. I have rebuilt many t-cases due to people running in auto all the time due to this I have attached a service bulletin that addresses this issue: PLEASE PAY SPECIAL ATTENTION TO THE LAST LINE.

Subject: Bearing or Metallic Grinding Sound While Operating In Auto, 4HI or 4LO Modes

Models: 2009 Cadillac Escalade Two-Mode Hybrid

2007-2009 Chevrolet Avalanche, Silverado, Suburban, Tahoe, Tahoe Two-Mode Hybrid

2007 Chevrolet Silverado Classic

2007-2009 GMC Sierra, Sierra Denali, Yukon, Yukon Two-Mode Hybrid, Yukon XL, Yukon XL Denali

2007 GMC Sierra Classic

Equipped with Magna Transfer Case RPO NP1, NP8, NQF, NQH

Condition/Concern:

Some customers may comment about a noise in the transfer case in either AUTO or 4WD. This may sound like a noisy bearing or a metallic grinding sound. It may also be accompanied by a C0327 DTC. The transfer case noise may be caused by an apply plate bearing failure. As pressure gets applied to the clutch pack the apply plate bearing gets loaded. Continuous operation in either AUTO or 4WD shortens the life of the bearing.

Note: Although there will be some characteristic noise while operating in 4wd, a NQF transfer case it is not equipped with a apply plate or apply plate bearing due to not having a internal clutch. If a noise is heard in a vehicle equipped with a NP1 or NQF transfer case see the operating guide lines below and compare to a like vehicle with similar mileage prior to attempting repairs.

Recommendation/Instructions:

The apply plate bearing designs in these transfer cases are not rated for continuous operation. They are intended for intermittent operation only when 4WD is required.

Long periods of continuous operation have been experienced in the U.S northern border states and in the provinces of Canada. This type of operation will shorten the life of the transfer case and in particular the apply plate bearing. As a general rule transfer case selector switches should be left in the 2HI mode unless road conditions dictate otherwise.

The following is a guideline for the proper use of 4WD in Magna transfer cases RPO's NP1, NP8, NQH and NQF.

1. 2HI mode sends all of the drive train torque to the rear wheels. This provides the most fuel efficient driving mode.

2. Auto/4WD mode when engaged constantly monitors the vehicle's drivetrain to provide optimum traction as road conditions dictate. Torque is automatically transferred to the front wheels to provide seamless 4WD operation. Auto mode is intended for on-road driving that includes rain, snow, ice and gravel.

3. 4HI provides enhanced traction for snow, ice, and gravel and most off road conditions. It is not intended for use on dry pavement.

4. 4LO provides enhanced traction and increased torque multiplication to handle extreme on and off road conditions such as steep hills, deep sand, mud, snow and ice. 4LO can also be used during boat launch operations for increased torque availability.

Note: 2-4 Not intended for continuous operation.

Keep it in 2wd unless you have a reason, wanting the extra traction, or otherwise. The only 4wd/AWD models meant to be as such all the time are systems like in the Denali and Escalade, which are different, full time AWD.

Otherwise, you're fine driving...and because of how it's tuned stock, the trans can feel funky from time to time, but if something actually does seem abnormal, it never hurts to have a dealer check.

Spurshot · April 4, 2010

I would advise using 2 Hi as well. My truck has a noticeable driveline drag in "Auto" and I can feel it in sharp turns. I use "Auto" for really heavy rain/thundershowers for short times on pavement. Dry streets get 2 Hi. I bet you find some mileage improvement in 2 Hi over "Auto".

KeithD · April 4, 2010

Trans is normal. Check your trans temp on those cold mornings, you'll see how cold it is, and be able to see how much better it shifts as it warms up.

Your old lady driving style doesn't sound like much fun, and I'm getting better mileage than you...

Rule of thumb for the 4x4 is if its dry, use 2 hi. I'll leave it in auto during the snow storms, the system works quite well. Pavement is rarely seen on the intown streets during the winter months, and 2 hi is fine for me. The traction control/stablitrac is a very good babysitter.

I like to run through all modes every month or so just to make sure they are working. I don't believe there is any reason that leaving them idle would not make them work, I'd just hate to find out that something has gone wrong when I need it the most.

Congrats on the truck.

BigZed · April 5, 2010

Thanks caddycruiser for posting that bulletin!! I'm definatetly going to keep it in 2HI for now on. I'm glad I posted my concerns bc for awhile I wasnt going to based on the classic "dumb question syndrome".

This forum is fantastic!