Most Reliable GM Truck Engine

customboss · January 22

304 BIG BLOCK GM V6 was most dependable GM engine. When GMC stopped making their own truck engines and switched to Chevy we started the slide to mediocrity.

silveradosid · January 24

not many people know about that engine and they are hard to find

Atlas · January 27

Is the rate of failure on the 4.3 V6 trucks with AFM about the same as the 5.3?

Pre-2013, the 4.3 was ancient, but very simple and reliable.

newdude · January 27

2 hours ago, Atlas said:

Is the rate of failure on the 4.3 V6 trucks with AFM about the same as the 5.3?

Pre-2013, the 4.3 was ancient, but very simple and reliable.

The LV3 Gen 5 4.3 Ecotec3 seem to hold up rather well. They still can have lifter failure though. They do run 5w30 where the 5.3 and 6.2 run 0w20, so "perhaps" there's a factor there but no guarantees.

The LV1 4.3 in the Express/Savana do not have AFM.

Snow White · March 3

if it has no computer, no abs, a manual transmission, and no emissions it'll cost you 1/2 of a new truck but is still 40K... and is probably in very good shape. the safety is far less.... thats the down side. K20 is the way if you ask me. rebuilt 454 is great. ideally you have holley efi on it and you'll never buy another if it doesn't rust out.

square body forever.

Edited March 3 by Snow White

jumbo-slaw · March 5

On 3/3/2026 at 6:47 PM, Snow White said:

if it has no computer, no abs, a manual transmission, and no emissions it'll cost you 1/2 of a new truck but is still 40K... and is probably in very good shape. the safety is far less.... thats the down side. K20 is the way if you ask me. rebuilt 454 is great. ideally you have holley efi on it and you'll never buy another if it doesn't rust out.

square body forever.

uh huh, until its stolen and you have to walk. That's the problem with the 01-06.5 trucks, get one in good shape and it'll be stolen. Highly desirable and not by just us.

OP, if you want reliable you're going to have to pay for it and keep up on maintenance.

PunchT37 · March 9

On 1/27/2026 at 10:39 AM, newdude said:

The LV3 Gen 5 4.3 Ecotec3 seem to hold up rather well. They still can have lifter failure though. They do run 5w30 where the 5.3 and 6.2 run 0w20, so "perhaps" there's a factor there but no guarantees.

The LV1 4.3 in the Express/Savana do not have AFM.

One wonders why the oil spec change? Could it be the added balance shaft?

jumbo-slaw · March 13

On 3/9/2026 at 5:50 PM, PunchT37 said:

One wonders why the oil spec change? Could it be the added balance shaft?

Snow White · March 14

On 3/5/2026 at 11:46 AM, jumbo-slaw said:

uh huh, until its stolen and you have to walk. That's the problem with the 01-06.5 trucks, get one in good shape and it'll be stolen. Highly desirable and not by just us.

OP, if you want reliable you're going to have to pay for it and keep up on maintenance.

not that hard to prevent, kill switch on the positive battery cable, no dumb thief is going to be smart enough to look for a kill switch and just hide the switch in the frame rail.

Grumpy Bear · March 14

On 3/13/2026 at 3:02 PM, jumbo-slaw said:

That is data I collected on my personal truck showing how both water temperature and base oil types affected bulk oil temperatures. I did a similar study changing viscosity later. For the study in question all three oils were 5W30. I'm currently doing a study using different weights v wear metals. A guy can learn a bunch no one will tell you if you are willing to PAY and put in the time. You also learn there is allot of lies told by marketing and OEM's and swallowed whole by Social Media drones.

Grumpy Bear · March 14

On 1/18/2026 at 8:03 PM, GN2018 said:

I’m looking for a truck/suv for my daughter. She tows a small trailer so I would prefer a towing package however, my biggest concern is what engine to get. My fear is her getting an engine with fuel management and the engine blows up on her. Is there any engines that are fairly described as bulletproof? I’m not sure what years or engines to look for as I begin my search. Any help would be appreciated.

I don't know how big a trailer she pulls but if it is small and my main concern was longevity I'd put my money on the original IRON 4.3 V6. 85-86 LB1 carbureted or 93-95 LB4 with throttle body injection in a CK. Darn near unkillable if maintained. Dad's had two go over 500K and remain oil tight and oil stingy. He replaced a few water pumps and a front cover seal on the first one.

BIGDOGx · March 17

On 3/5/2026 at 11:46 AM, jumbo-slaw said:

uh huh, until its stolen and you have to walk. That's the problem with the 01-06.5 trucks, get one in good shape and it'll be stolen. Highly desirable and not by just us.

OP, if you want reliable you're going to have to pay for it and keep up on maintenance.

01-06.5 are desirable?? I don't get that because they were not the prettiest truck and if you think these newer gen v-8's are noise lol, you had like a 80% chance you would get a motor that suffered from piston slap. I had a coworker who bought a brand new 2001 and literally a year and a half later you could here that thing start from a 1/4 mile away the piston slap was so bad. Right now the only gmt-800's i see on the road are beat up pretty bad, just by age and weather conditions.

KARNUT · March 17

The 01-06s GM trucks are my favorite. I had several new and used. I would put programmers on them, true duals and cold air intakes on each one. Run them up and down pipelines, drive hundreds of miles daily. I have an 02 Avalanche currently my grandson now drives. I always have an eye out for one. My brother in law is passing 275K on his 06 Tahoe. Did they have problems? Probably. Did I have any,? No. There’s still plenty around me.

BIGDOGx · March 17

2 hours ago, KARNUT said:

The 01-06s GM trucks are my favorite. I had several new and used. I would put programmers on them, true duals and cold air intakes on each one. Run them up and down pipelines, drive hundreds of miles daily. I have an 02 Avalanche currently my grandson now drives. I always have an eye out for one. My brother in law is passing 275K on his 06 Tahoe. Did they have problems? Probably. Did I have any,? No. There’s still plenty around me.

Got to love that Texas weather, i live in Massachusetts and they all literally leave pieces on the roads when they hit a bump they are all so rusted out most times.

I still don't understand the "they are on the top of list for car thieves" though. I mean there really are no factors imo that make them a valued item for car thieves unless i'm missing something.

KARNUT · March 17

10 minutes ago, BIGDOGx said:

Got to love that Texas weather, i live in Massachusetts and they all literally leave pieces on the roads when they hit a bump they are all so rusted out most times.

I still don't understand the "they are on the top of list for car thieves" though. I mean there really are no factors imo that make them a valued item for car thieves unless i'm missing something.

I agree. They are pretty basic. Easy to modify and drive great with little intrusion.