Edmunds Answers questions

I'm confused about weights of oil, what is the difference between 5W30 and 10W30?

rreid2 — Fri, 01 Feb 2008 21:14:14 GMT

I had a 99 Silverado with a 6liter and put 10W30 in it according to the temperatures in the owners manual. Wouldn't it be the same on my 2007 8.1liter GMC Sierra? My 6liter had 190,000 miles on it and never burned oil.

Oil weight for Silverado

rreid2 — Fri, 01 Feb 2008 20:16:47 GMT

1. Even though it calls for 5W30 GM dealerships are using 10W30, is it because of the climate. We live in west texas. I have 10W30 in all my vehicles because I heard of a recall on the Castrol GTX 5W30 oil. And I prefer Castrol GTX. I called GM and they know nothing of the recall. And now I'm in the process of changing out all the vehicles to 5W30 again. Since you answered my question.

Can anyone tell me if there is anything special to change a fuel filter on a 2007 GMC Sierra Diesel Truck?

steveneedstokn — Sat, 01 Mar 2008 15:32:27 GMT

Am looking for info. on changing the fuel filter on a new 2007 GMC Sierra Diesel Truck. Have not found anything on line that discribes in detail, if anything special as to prime it or just reach in replace then cap it and go ?

Is 70k a lot of miles on a GMC Duramax diesel?

afdjpirrone — Thu, 06 Nov 2008 21:07:42 GMT

Looking to buy a 2005hd withe duramax diesel 70k miles on it. Is this a lot of miles

What is most likely the cause of a front end growl/grind in 4WD only and during deceleration only? GMC Sierra 2500 HD.

pkeagle — Mon, 01 Dec 2008 09:17:17 GMT

2004 GMC Sierra 2500HD 4x4
Facts:
*There is a Growl/Grind coming from the front driver side as far as I can tell.
*Noise is present during deceleration 30mph and under.
*Noise can not be heard during acceleration.
*Noise exists while coasting in neutral as well.
*There are no visible leaks anywhere?
*Noise is amplified while turning.
*Noise goes away after shifting back into 2WD.
*There seems to be no issues shifting into and out of 4WD Hi or Lo.
*Tire wear is consistent and even.
*Front inside brake pads are not engaging rotor on either front wheel.

Actions:
*Changed out front differential gear oil. Drained a purplish, thick oil w/ what looked like metal flakes/sparkles. Magnetic drain plug had a few small splinters. (<1/8") Refilled w/ Valvoline 80W90 Synthetic Gear Oil - Noise still there. *Local performance shop seems to think it might be a wheel/hub bearing assy. If a bearing, would the noise be consistent during accel and decel in 2WD or 4WD? So I have my doubts about this being the issue. Questions: *Does the front differential disengage during decel or is it engaged all the time in 4WD? *If it does disengage, what controls this? Front Axle Shift Motor? *What do I look for to tell if it is a CV Joint? *Any suggsestions or help is appreciated!!!

Bucket of sand in my tranny? 2003 GMC Sierra 2500 HD.

sj44107 — Mon, 09 Feb 2009 22:39:21 GMT

My 2003 GMC Sierra 2500 HD has 110,000 miles, recently began making a very loud noise like someone poured a bucket of sand into the transmission, when I punch the gas, it goes away. Seems to be getting worse the more I drive it. Anyone have a similar experience?

Why is there still 1" of play in my steering after gear box, pitman and idler arms were replaced on '05 GMC Sierra 2500HD?

smithstorm — Tue, 26 May 2009 20:00:51 GMT

I own a 2005 GMC Sierra 2500HD 4x4. I've had two steering shafts replaced already, but I need another due to the return of the knocking noise. I've had the gearbox, pitman and idler arms replaced this year, yet I can't get rid of the 1" of play in the steering wheel. What could be the reason for the play in the wheel?

Axle shaft spline count and/or ring and pinion ratio for a 2003 GMC Sierra 2500 HD?

bready1 — Sun, 06 Sep 2009 06:32:41 GMT

Want to fit a rear locking diff to a 2003 GMC Sierra2500 HD. What is the spline count of my rear axle and or ring and pinion ratio? bryan mc

2007 GMC Sierra 8.1L which oil to use 10W 30 or 5W 30, need to know.

rreid2 — Thu, 31 Jan 2008 20:40:04 GMT

Also want to know at what mileage point should I change over to synthetic oil?

We have a 2003 GMC Sierra 2500HD. It won't start. We think it is the passlock system. How do we disarm it?

snowwolf77 — Fri, 04 Jul 2008 11:36:39 GMT

We have a camper on our truck and we had the trucks alarm system armed while we were climbing in and out of the back. According to Onstar, we might of triggered the passlock system. They suggested leaving it totally alone for at least 10 minutes and then it should start. We tried that and it still didn't work. It sounds like the fuel isn't getting into the engine. It will start to turn over but it won't fire.

I have a 2001 GMC 2500 HD. Tthe brake lights work on the truck, but it's not lighting my trailer brake lights.

polyman60 — Thu, 18 Sep 2008 17:37:06 GMT

When I hit my brakes, the truck brake lights work, but they dont light my trailer brakes. All other turn signals and running lights on the trailer work, though. I checked the voltage at the connector and have voltage for the turn signals but no voltage when you step on the break. Is there a fuse or relay? I checked all the fuses under the hood and fuses on the side console.

What size tires are included with the 2008 GMC Sierra 2500HD SLE2 4 door extended cab sb with standard box?

gpmiracle — Mon, 27 Oct 2008 12:35:41 GMT

What size tires are included with the 2008 GMC SIERRA 2500SD SLE2 4DR EXTENDED CAB WITH STANDARD BOX?

Option code "ZER - LT265/75R16 SPARE TIRE" implies that the spare tire and wheel is NOT included with this truck. Must this option be purchased to get a spare tire and wheel with this truck

2005 GMC 2500HD diesel lost power, blew ignition fuse while pulling toyhauler up grade. Dealer found some gas in fuel.

bigtoy1 — Mon, 16 Feb 2009 15:42:30 GMT

My 2500hd lost power and blew the ignition fuse while towing my trailer up the grade. Replaced the fuse and same thing happen 1 mile later. Had truck towed to deal in El Centro. Filled up with fuel at a small gas station just 5 miles before I broke down. Dealer indicated that my diesel fuel was contaminated with gas (not sure if mini mart tanks were contaminated or if dealer was looking for extra service (my receipt shows I poured from the diesel pump). Is it possible that having a 50/50 mix of diesel and gas could some how cause the lost of power and blow the ignition fuse? If not, is it possible that the transmission upon downshifting or the loud fan that comes on to cool the motor could draw to much current and blow the ignition fuse (not sure they are even wired to the ignition circuit?) After having the fuel lines and tank drained I have put 200 miles on the truck with no problem. I have not tried pulling the trailer up the grade yet.... still afraid the problem is not fixed. Dealer only replaced the fuse and looked for harness shorts vis chaffed wires. They could not reproduce the failure.

I have a 2006 GMC Sierra 2500HD. Where is the cabin filter located and how do I get to it to change it? Thanks, JL

jjlaroch — Wed, 18 Feb 2009 16:23:44 GMT

I don't know where the cabin filter is in my 2006 GMC Sierra 2500HD. I have a new one but don't know where the heck it is. I'm feeling pretty dumb right now. Dealer is of no help, all they want is me to bring it in for them so I can pay through the nose.

2003 GMC Sierra 2500HD 6.0L. Check engine light turned on and odometer display reads (reduced engine power).

rockscrubber — Mon, 02 Mar 2009 20:51:27 GMT

These are the three codes that were stored on computer..p0171 , p0174 , p1518 . any help on what to replace..

Buying a GMC 2500HD SLT 4WD.

padres — Thu, 16 Apr 2009 14:59:07 GMT

Thanks for all the info.! It'll take while to digest it all. Here's the deal. As you suspected, I want a "near" fully loaded 2500HD SLT 4WD long bed crew cab, black exterior. I've searched all over the nation using the GMC web site and have found the four trucks in TX, one in Idaho, one in FL and one in PA. I'm in Yuma, AZ and I have bought from three of the dealers here in town in the past and don't trust any of them. In fact, I e-mailed my local GMC dealer two months ago and never got a response. Since I'm now retired, I have time to invest in all the research and follow up. The 0% works real well for us and I assumed by going directly to the dealers that I know have my truck, I don't have to screw around with the one knucklehead dealer here in town. They all seem to have the attitude that if you don't like the offer they give, go to Phoenix or San Diego. Fine, I'll go to Texas! I REALLY appreciate all your information.

2008 GMC 2500HD diesel with 10k miles getting 14 MPG with 80% highway miles. Not towing. Dealer says MPG OK.

motorhead60 — Sun, 21 Jun 2009 22:22:14 GMT

Brand new was getting 16-17 MPG. Power is also a problem. Drove a new one on dealer's lot and it took off - complaints are not being addressed by 2 separate dealers. They tell me to "break it in by 25k" and mileage will change????

03 GMC 2500HD gas mileage?

gmc03 — Sat, 01 Aug 2009 02:37:25 GMT

What should I expect for gas mileage on a 03 GMC 2500HD?

Can a Hypertech Programmer destroy an engine?

tanya_789 — Mon, 03 Aug 2009 21:21:34 GMT

I have a 2005 GM Sierra HD2500 6.6L Duramax Diesel pickup. One day when coming to a stop the engine quit.
Terra Nova Motors, informs me that damage to the engine involves a broken piston and a broken valve. They are also claiming that my warranty, which has 10,000 kilometres left, is void because I had installed engine performance tuning software by Hypertech (hypertech.com). When I purchased the device I was informed that my warranty would be unaffected. After speaking to several mechanics they felt that there was no way possible that the programmer could cause engine damage of that magnitude, if any at all.

GM continues to claim that the programmer is the cause of the damage. Meanwhile, I feel no proof has been provided that this is actually the case.

Ultimately they want $20,000 to replace my engine while I continue to make payment on my truck to the tune of $800.00 per month for a truck that is of no use to me or anyone else.
The balance owing on my loan is just over $30,000.

6 ltr GMC Sierra 2500HD shuts down every now and then.

hoofe249 — Wed, 19 Aug 2009 15:31:44 GMT

My 05 GMC Sierra 2500HD 6.0 ltr every now and then shuts down, display says low engine power. It's still running but there's no throttle. I shut it down and wait a few minutes and restart - runs fine, but the check engine light is on until the next restart. Any ideas?

Gas mileage enhancer for 06 GMC Sierra 2500 HD 6.0L V8?

tpcox — Mon, 07 Sep 2009 00:43:31 GMT

I have an 06 GMC Sierra 2500HD 6.0L V8 gas engine. Is there anyway I can improve my MPG? Right now I get about 10.

Low oil pressure at idle on a 2004 GMC Sierra 2500HD Duramax.

rick04lly — Wed, 16 Sep 2009 16:50:32 GMT

2500HD Duramax with 90,000 miles. Notice oil pressure fluctuations as follows:

At cold start-up reading 60 - 70 psi also under load. However as vehicle warms up psi drops to around 20-30 when it is warmed up. The light does not come on yet and the crankcase is full with the proper weight Rotella oil.

I would believe I should replace the oil pump with a high volume pump? I would like to be ready in the event the light starts coming on.

I have a 2008 GMC Sierra 2500HD factory wired switch for a roof light. How do I drop access the wire bundle?

herk7769 — Mon, 18 May 2009 14:30:20 GMT

I have a 2008 GMC Sierra 2500HD CrewCab with the factory wired overhead panel switch for a roof mounted light. How do I access the wire bundle? I do not want to drop the headliner if I do not have to. In fact, I have no idea how to do it without damage to the headliner. There must be an easy way to access the wire bundle and/or locate a spot on the roof above or close to the wiring. If so I would LOVE to hear about it. Thanks, Lou

Changing fuel filter step by step directions - 2001 Chevy Silverado 2500HD Crew Cab Durmax Diesel

rv_gypsy — Tue, 29 Jan 2008 00:11:54 GMT

Need instructions or a web site with step by step instructions on changing fuel filter.

2001 Chevy 2500Hd 6.0 liter I have misfire on 1 & 5 cylinder what is the cause?

cajama — Thu, 21 Feb 2008 17:19:02 GMT

I have a 2001 2500HD crew cab w/85000 miles. i have been getting a misfire on 1 and 5 clyinder. what could be the cause.

I have a 2002 Chevrolet C/K 2500HD 6.0 and it will start and then shut right back off. It will not stay running

kobelco269 — Sun, 02 Mar 2008 15:44:23 GMT

I had a roll over and after the roll over it started and run good but then I went to start it and then it started and shut right back off and has done that ever since.

2003 Chevy Duramax 2500 HD. Occasionally gauges on instument panel do not come on.

montdura — Tue, 25 Mar 2008 20:39:36 GMT

duramax 6.6, 2003 chevy duramax 2500hd pickup. 81,000 miles. sometimes at startup, the gauges on instrument panel do not operate. shut off and restart usually will be ok.

I have a 2002 Chevrolet SIlverado 2500 HD 8.1 that died while driving, keeps blowing ECM fuses. HELP

solocam — Thu, 05 Jun 2008 22:28:00 GMT

Replaced fuse a couple of times still blows, put 25amp in has not blown but it intermentily falls onface then takes off, sputters

Chevy Silverado 2500 HD payload capacity. Truck camper question,

bisinc — Mon, 23 Jun 2008 18:00:02 GMT

I've been looking at a '01, '03 and '05 Silverado LS Ext cab 2500HD 6.5' bed for my Lance Squirelite slide in truck camper (dry wt 1961 lbs). On the spec sheet I noticed all 3 have different "payload capacities" ranging from 3,092 lbs (the '01) to 3774 lbs (the '05). If the GVWR is the same for all 3, and the front and rear GAWR ratings essentially the same, why the difference? I thought they all pretty much have the same frame.

Also noticed in the '01 glove box that the truck camper load capacity sticker says only 2,024 lbs including passengers. Why is that so much less than the payload capacity (which also includes passengers) of 3,092?? I assume all 3 are more than capable of handling my camper but maybe not?

Chevy 2500 HD mpg?

kmarshall205 — Fri, 25 Jul 2008 16:24:38 GMT

I have a 2006 2500HD Chevrolet Duramax/Allison, it has a 6'' pro comp lift with 35'' tires. I am only getting 11mpg at best, and it is killing me, is it because of the lift kit? should i change my gear ratio, and what else can i do to get my mpg up?

Chevrolet SIlverado 2500HD gearing?

kmarshall205 — Tue, 29 Jul 2008 03:23:39 GMT

I have a 6" lift with 35" tires on my chevy 2500HD, and of coarse my mileage isn't as good as stock. Ive been told if i change my gears to 456's, it will bring my mileage back up close to stock. Does anybody know about this and if it will make that big of a difference? I am also getting Banks intake, programmer, intercooler and exhaust installed, which is also supposed to help my mileage. will this really make that big of a difference, or will my truck just be a hell of a lot faster?

2006 Duramax Diesel 4WD Crew Cab. What causes oil pressure gauge fluctuations? Is there a need for concern?

boodog — Mon, 08 Sep 2008 15:34:45 GMT

Purchased used 2006 2500HD Duramax in remarkable shape. Notice oil pressure fluctuations as follows: At cold start-up reading 60psi also under load. However as vehicle warms up psi drops to around 30 this also occurs at highway speeds---vehicle in overdrive. What is the cause? Vehicle runs fine no oil consumption, no lights on just fluctuations in the gauge

01 Chevy Silverado 2500HD engine misses and goes dead. Have changed the crank sensor and one other. Still happens. Any thoughts please?

sam110 — Sat, 20 Sep 2008 12:43:03 GMT

just all at once started to do this will die if you don't power brake it. have changed the crank and cam sensor still have the same problems. when it does this he temp gauage goes nuts from 260 to 0 and back when the engine picks up it goes back to normal 190 please can someone give me a suggestion thanks sam It has never run hot just te guage goes crazy I know it is an electrical probem but am lost at were to look. this is my only transptation and I'm retired on disbility and can't aford to take it to the dealer any help will be greatly appreacited this truc has he 6.0 enginein it

Chevy SIlverado 2500HD . Changed waterpump got a squeak.

seabass4 — Fri, 17 Oct 2008 21:07:45 GMT

changed belt, idler pully didnt fix. squeek is coming from power steering pully. Belt dressing does not help, is it possible water pump took alignment out enough to cause squeek.

I have a 02 Chevy Silverado 2500 HD 8.1L Allison transmission and it keeps shutting off on me. What could be the problem?

CDC11 — Mon, 15 Dec 2008 14:45:05 GMT

I have already replaced the fuel pump twice now and it is still shutting off while driving down the road. When I try to restart it will role over but not start. If I wait 5 or 10 minutes it will then start.

I have a 2003 Chevy Silverado HD 2500 4x4 crew cab and the trip gauge goes to zero and shifts to total hours and odometer by itself.

basdog — Thu, 01 Jan 2009 03:10:34 GMT

while driving the language changes and it cycles from total hours, trip and odometer by itself. I have only 38000 miles on my 2003 2500HD duramax.

What's the correct type of differential fluid (front) for my 2001 Chevy Silverado 2500HD 4 wheel drive (diesel)?

bubba40 — Thu, 01 Jan 2009 22:45:14 GMT

My owners manual indicates w80-90 gl-5, i think ( 9.5 RG),some auto techs think i should use synthietic fluid,does anyone know which is correct?

2004 Chevy Silverado 2500 rear door locks will not work. What relay controls this and where is it?

FloridaRon — Mon, 05 Jan 2009 08:17:10 GMT

2004 Chevy Silverado 2500 rear door locks will not work, what relay controls this and where is it? They do not work from the door switch or from the key fob unlock. Thanks, Ron

I hate the stock wheels on my new 2009 2500HD Chevy Silverado.

dbarmore — Mon, 16 Mar 2009 17:05:45 GMT

i just got my new Silverado 2500hd 4x4 in Feb. I would love to put bigger wheels on it, but i don't really want to modify it if i don't have to. What is the largest i can go without modification?

Problem with horn on '04 Chevy Silverado 2500HD.

null — Wed, 25 Mar 2009 12:29:07 GMT

Horn stops working intermittently. When it does work it is usually best activated by pushing lower portion of steering wheel hub. Dealer has fiddled, but finds nothing specific and often states nothing wrong till I go to leave and horn again doesn't work. What should I look for? Thanks

Source of 2002 6.0L Chevy Silverado 2500 HD noise when decelerating - unable to determine source.

gofe — Sun, 29 Mar 2009 19:36:52 GMT

When decelerating down a long hill (foot off throttle) I occasionally get a gear grinding noise like the transmission is trying to shift improperly. Braking or shifting does not stop the noise - only when I hit the throttle (even just a little) will it stop. When I let off the throttle it will come back. Otherwise the transmission works fine. The truck has 100K miles and when the transmission oil was changed there was no indication of abnormal wear. Any suggestions on where to focus my attention?

What is the distance from wheel well to back of truck bed without bed liner in a Chevy Silverado 2500HD 6 foot bed?

cgeiser — Thu, 02 Apr 2009 10:22:08 GMT

Currently have a bed liner and want to add truck box. Need to know distance, inches, from the wheel well to the back of the truck bed - cab of truck without the liner.

replacing rear axle seal on Chevy Silverado 2500HD. Is it a press in/press out seal?

silvercharlie — Sat, 04 Apr 2009 10:33:49 GMT

Are any special tools needed to remove the wheel hub?

What is the recommended maintenance at 100,000 miles on a 2000 Chevy Silverado 2500HD? Thanks.

mminder — Mon, 20 Apr 2009 17:36:26 GMT

Spark Plug wires?, spark plugs?, distributor? brakes?, transmission. etc.

When checking the spark plug wires on my 2000 Chevy Silverado 2500 HD, what should the resistance be?

mminder — Thu, 23 Apr 2009 17:18:17 GMT

Thanks steve and tony78 for the previous info about what maintenance. Now I need how many ohms resistance for the spark-plug cables..Thanx again

When I shift into 4 wheel drive I hear a slipping noise and the tires don't grab. It's a 2002 Chevy HD2500 8.1 with Allison.

kchvy02 — Fri, 01 May 2009 01:10:59 GMT

Wheels won't grab when in 4 wheel drive on slick ground and I can hear a clicking noise. Any ideas?

I need to change the front passenger side bearing on my truck. 05 Silverado 2500HD 4x4 Duramax. Will it be the whole hub assembly?

dmax4x4 — Fri, 26 Jun 2009 18:41:54 GMT

If it is the whole bearing assembly, how hard is this to change? Will the shaft need to be pulled or will the assembly slide off the shaft? Not sure if I want to try this myself or take it to a shop. The hub assembly is $250 and so I assume the labor will be up there too. Any help or tips will be greatly appreciated. Thanks.

2004 Chevy Silverado 2500 HD. Passlock theft deterrent system light on instrument panel will not shut off.

in_the_wind — Mon, 29 Jun 2009 18:52:24 GMT

Light stays on all the time, the alarm system works and the truck starts.How do I reset, etc. Thought that it might be a ground wire, but not sure where the instrument panel is grounded too.

2002 Chevy Duramax Diesel 2500HD 4 wheel drive won't start at warmer temps (80+ degrees).

dep001 — Mon, 21 Sep 2009 10:46:15 GMT

My 2002 Durmax 2500HD starts fine during the cooler parts of the day, but won't start when temps. are over 80 degrees after sitting for 4 hours. This has happened to me the past 4 days in a row. It will start again later in the day when temps drop back down to the 70's.

Where is the cabin air filter located on a Chevy 2500HD?

hemidan — Wed, 23 Sep 2009 12:42:19 GMT

I need to change the cabin air filter on a 2005 Chevy 2500HD with A/C. I don't want to spend a lot of time looking for it. Does anyone out there know the procedure and location? I took a quick look and it is not out in the open, no cover or other obvious place showing.