New owner - 2004 Silverado - where to begin?

Jonathan Herring · December 1, 2021

Maybe this is the wrong forum - if so, I apologize. First post.

I recently purchased a 2004 Silverado LS, Extended Cab, 5.3. 153,000 miles. (I still can't believe I just bought a vehicle with over 150k miles - I normally buy used, but try to find something with much lower mileage .. but you know, "the market is bad", etc.) One owner truck, clean CarFax (I realize that CarFax doesn't always tell the full story...). From what I can tell, it was owned by someone fairly local to me (NC). The truck appears to be clean - no weird stains in the carpet or on the seats; underside is clean and - at least visually - appears to be in good shape. Previous owner did regular oil changes. There are some issues that one might expect with a 17 year old truck - for example, the headlights and tail lights are badly fogged - I've ordered replacements. The dash doesn't completely light up - which I understand is common. The passenger window sticks and will come down, but not go up. The locks don't seem to consistently lock when the truck is put in drive. Key fob does not work - which I should have discovered before buying the truck - but these seem like fairly minor things overall.

I don't know what brand or weight of oil the previous owner used, I only know it was changed frequently by the dates noted in the owner's manual. Given the mileage, should I start using oil "for high mileage" engines? Historically, I've used Havoline 10W30 (I had a 2004 Colorado 3.5 which was running great at 177,****** miles, until I was rear-ended and it was totaled). Any insight would be appreciated.

KARNUT · December 1, 2021

1 hour ago, Jonathan Herring said:

Maybe this is the wrong forum - if so, I apologize. First post.

I recently purchased a 2004 Silverado LS, Extended Cab, 5.3. 153,000 miles. (I still can't believe I just bought a vehicle with over 150k miles - I normally buy used, but try to find something with much lower mileage .. but you know, "the market is bad", etc.) One owner truck, clean CarFax (I realize that CarFax doesn't always tell the full story...). From what I can tell, it was owned by someone fairly local to me (NC). The truck appears to be clean - no weird stains in the carpet or on the seats; underside is clean and - at least visually - appears to be in good shape. Previous owner did regular oil changes. There are some issues that one might expect with a 17 year old truck - for example, the headlights and tail lights are badly fogged - I've ordered replacements. The dash doesn't completely light up - which I understand is common. The passenger window sticks and will come down, but not go up. The locks don't seem to consistently lock when the truck is put in drive. Key fob does not work - which I should have discovered before buying the truck - but these seem like fairly minor things overall.

I don't know what brand or weight of oil the previous owner used, I only know it was changed frequently by the dates noted in the owner's manual. Given the mileage, should I start using oil "for high mileage" engines? Historically, I've used Havoline 10W30 (I had a 2004 Colorado 3.5 which was running great at 177,****** miles, until I was rear-ended and it was totaled). Any insight would be appreciated.

Almost 2 years ago I bought my 02 Avalanche as around town personal vehicle. It had 168K and is well maintained with complete records. The oil was changed regularly but nothing else. So I changed all the fluids. I’m at 178K now aside from some rattles it’s a jewel.

dna9656 · December 1, 2021

You can get new key fobs from about any auto parts store or better yet price wise from Amazon.

You can polish the lenses clear again with a kit from the auto parts store or Harbor Freight. Tooth paste and a buffer works too. Do a compression check to see if your engine is tired. Your window sounds like a tired switch is to blame again Amazon for that switch.in the least, I have about the same mileage as you on my 06 Avi, I did some major work on mine (ck my other posts) that I would do on your truck. Havoline is some good oil. I have taken down engines that Havoline was in, they were spotless, stay away from Quaker sludge. If you can solder on a circuit board you can replace the dash LEDs, there are kits available , yep ck Amazon.

Sharpz · December 1, 2021

all of what you mention is extremely mild issues. I too have a 2004 with the 5.3. It has over 325k on the engine, tranny, and differentials. I use this truck daily and put about 300 miles a day on, and to be honest I would not hesitate to take it anywhere. Since Ive owned this truck used mobile 5 w 30 full synthetic. I know some have issues with it, but I have had zero. At the 3k, mark or there abouts I will get a check oil message, and I will find it is down about 3/4 of a qt, which is fine with me.

Before replacing the actuator or motor try cleaning the connections up a bit. Sometimes just unplugging them and plugging them back in will eliminate any symptoms or a weak or slow motor. Spray all of your locks with PB or WD, as well as their connections.

Try programing your FOB using the suggested method for your year truck. You wont need to get a dealer or locksmith to do that.

Keep in mind there are items that are going to go relatively soon, if they havent already. The HVAC lines tend to become brittle and can start leaking coolant. Water pump I think I had to replace at 220k and the oil pressure sensor.

Jworks · December 1, 2021

OIL. All of us have a diff opinion on oil, I suppose. Havoline is fine. Currently I'm using 100% synthetic because I've decided to let the dealer do it; getting old i guess. BUT,,, before that I had a 4.3 in a '94 GMC pu and later a '05 GMC pu. On the '94 GMC I used 10w-40 Valvoline and a can of STP for years. Around 250k started using a little oil so I went to Castrol 20w-50 and a can of STP. Yes, thats correct, 20w-50. And YES STP. I sold it after 21 years of use, 484k miles, still using 20w-50. When I bought the '05 GMC (5.3 eng) I used Castrol 10w-30 till it was wrecked. If you are going to use conventional oil there is nothing wrong with Havoline or any of the name brands. Personally, just my preference, I like Castrol. I had such good luck with it...and with STP in the 4.3 eng. With your 5.3 I am not sure about using STP. I would think the 5.3 has quite a bit of different specs and tolerances than the old 4.3 did. Just my guess. But STP has not issued any notices about not using it in newer engines. If I had your vehicle I would probably go with Castrol 10w-40.......you've got a lot of miles left on that truck. The dealership has told me it does not hurt one bit to go with synthetic oil after many miles of regular oil usage. Thats probably true --- I'm letting them put synthetic in. Yes, I know - thats a mix of opinion. Given yours is a 2004 with a 5.3, I'd recommend either the Havoline or Castrol. Weight is your choice. 10w30 or 40. If you choose 30 and it uses a quart, step it up to 40.

Jonathan Herring · December 2, 2021

Thanks for the input. I'll change the oil this weekend. Probably take it to a friend's shop for the radiator and transmission flush/change.

Looking at the headlights, I think you guys are right - I'll try a restore kit first. Seems I have little to lose there.

Key Fobs - I only received one when I purchased the truck, and it has a number "2" engraved on the back - but the truck doesn't have the programmable seat positions, etc. I'm wondering if they somehow gave me the wrong key fob.

For the dash, it's been a long time since I've done any soldering. Do you guys know of anyone in NC who repairs instrument panels?

thanks again.

Grumpy Bear · December 2, 2021

On 11/30/2021 at 9:17 PM, Jonathan Herring said:

Maybe this is the wrong forum - if so, I apologize. First post.

I recently purchased a 2004 Silverado LS, Extended Cab, 5.3. 153,000 miles. (I still can't believe I just bought a vehicle with over 150k miles - I normally buy used, but try to find something with much lower mileage .. but you know, "the market is bad", etc.) One owner truck, clean CarFax (I realize that CarFax doesn't always tell the full story...). From what I can tell, it was owned by someone fairly local to me (NC). The truck appears to be clean - no weird stains in the carpet or on the seats; underside is clean and - at least visually - appears to be in good shape. Previous owner did regular oil changes. There are some issues that one might expect with a 17 year old truck - for example, the headlights and tail lights are badly fogged - I've ordered replacements. The dash doesn't completely light up - which I understand is common. The passenger window sticks and will come down, but not go up. The locks don't seem to consistently lock when the truck is put in drive. Key fob does not work - which I should have discovered before buying the truck - but these seem like fairly minor things overall.

I don't know what brand or weight of oil the previous owner used, I only know it was changed frequently by the dates noted in the owner's manual. Given the mileage, should I start using oil "for high mileage" engines? Historically, I've used Havoline 10W30 (I had a 2004 Colorado 3.5 which was running great at 177,****** miles, until I was rear-ended and it was totaled). Any insight would be appreciated.

How about you go to the section of this site called "Hobbies & Lifestyle" then the last forum in that section is called "Vehicle Builds" and start a build thread. This sort of thing you are doing is prime for sharing. C'mon, let us tag along.

dmoff46606 · January 17, 2022

Before you replace the key fob, try changing the battery in it. It should be a CR2032.

Programming instructions are here:

I've got a 2004 Silverado with over 270,000 mi on it & I use 15W40.

When I was working with a defense contractor overseas 2004 - 2020, the company I worked for had a fleet of over 200 Tahoe's, Suburban's, and Silverado's (or the GMC equivalents) with the 4.8L, 5.3L and 6.0L engines that were fed a steady diet of 15W40 from the first oil change after delivery (new) to late 2018 (when we were forced to turn them in). Much of the fleet had over 500,000 km on them with no major engine repairs (they got the normal stuff - Sensors, Water pumps, Fuel pumps, and Oil pumps (and especially the O-Ring on the oil pick-up tube), etc.

I trust 15W40 in my LM7.

When it gets to the point when yours needs knock sensors, you may want to look at relocating them. There's a kit that allows you to move them along the oil pan rail (like the later LS engines) You can't use the later knock sensors because they won't talk nice to your 2004 ECM. This way you can avoid having to pull the intake to replace them if needed.

The links are here: LS Gen III Knock Sensor Extension – 36” WEKN030-36 (ictbillet.com) (ICT# 551216-KN30)

LS Gen III Knock Sensor Extension – 36” WEKN030-36 (ictbillet.com) (ICT# WEKN030-36) Don't worry that the links look the same, they will take you to the correct page that you need to be on for each part. The harness is made with GM sourced parts. Make sure that you use AC Delco knock sensors & ensure that the mounting surfaces on the engine block are clean to get a good electrical connection. You may be able to find the parts cheaper if you search by part#.

TurboTruck · January 17, 2022

3 hours ago, dmoff46606 said:

Before you replace the key fob, try changing the battery in it. It should be a CR2032.

Programming instructions are here:

I've got a 2004 Silverado with over 270,000 mi on it & I use 15W40.

When I was working with a defense contractor overseas 2004 - 2020, the company I worked for had a fleet of over 200 Tahoe's, Suburban's, and Silverado's (or the GMC equivalents) with the 4.8L, 5.3L and 6.0L engines that were fed a steady diet of 15W40 from the first oil change after delivery (new) to late 2018 (when we were forced to turn them in). Much of the fleet had over 500,000 km on them with no major engine repairs (they got the normal stuff - Sensors, Water pumps, Fuel pumps, and Oil pumps (and especially the O-Ring on the oil pick-up tube), etc.

I trust 15W40 in my LM7.

When it gets to the point when yours needs knock sensors, you may want to look at relocating them. There's a kit that allows you to move them along the oil pan rail (like the later LS engines) You can't use the later knock sensors because they won't talk nice to your 2004 ECM. This way you can avoid having to pull the intake to replace them if needed.

The links are here: LS Gen III Knock Sensor Extension – 36” WEKN030-36 (ictbillet.com) (ICT# 551216-KN30)

LS Gen III Knock Sensor Extension – 36” WEKN030-36 (ictbillet.com) (ICT# WEKN030-36) Don't worry that the links look the same, they will take you to the correct page that you need to be on for each part. The harness is made with GM sourced parts. Make sure that you use AC Delco knock sensors & ensure that the mounting surfaces on the engine block are clean to get a good electrical connection. You may be able to find the parts cheaper if you search by part#.

Yep, I agree. First I would just replace the battery and try to reprogram it. My last truck I just ordered a set of two from Amazon for $20, so it's hard to beat having extras. Programming takes 60 seconds and is super easy.

FWIW, I prefer oil with a little higher zinc. I wouldn't get too caught up in the weight/viscosity of the oil though. Oil pressure and oil level are just as, if not more, important than the weight rating. With that said, higher mileage vehicles will like a little heavier oil than brand new cars but it's not required.

ONE QUICK NOTE.... This is personal experience only...

I worked at a machine shop 15-20 years ago. My job was to tear down engines and then reassemble after we were done with them. I did everything from honda car engines to inline diesels that ran pump jacks and other oil field equipment and even a top fuel car engine one time.

I got into the habit of asking the customer what oil they used so we could recommend different products based on their application and how well their engine cleaned up.

What I discovered (ONCE AGAIN, PERSONAL EXPERIENCE ONLY, I'm not bad mouthing here) was that if the customer used Penzoil, the engine was going to have four times as much gunk and nasty sludge build up than any other. I'm not saying it was Penzoil and I can't say is was 100% every single time, but I would say it was easily a 90% chance the engine was caked with sludge versus any other only being like that 5-10% of the time. All estimates and I don't have any scientific proof, nor am I bad mouthing anyone, that's just my observation.

Edited January 17, 2022 by TurboTruck

dmoff46606 · January 19, 2022

My reasoning behind the swap to 15W40 was/is; #1. Improve oil pressure (the LM7 is pre-AFM & VVT, so I knew I could get away with just bumping the viscosity. It also sounded a little "loose" at idle and cold start-up with temperatures around 30 degrees or lower - going to 15W40 cured that). I may do my next oil change with 10W40 and look for one with a high zinc content. You are correct; the higher zinc content will provide a little more wear protection. I'm just trying to make it last as long as possible before I'm forced to rebuild or get a remanufactured long block to do it right.

Being on a fixed income I've got to save my pennies to ensure that I've got enough money to take no shortcuts when I'm forced to do it. I may even look for a low mileage used one - they're common enough where you can still find them at a reasonable price. I don't mind going for bone-stock because the LM7 has proven itself as an EXCEPTIONALLY reliable engine.