I have a 1999 ecsb 4x4 with 4.8 and 3.73 gears, it has 210,000 miles on it and i just drove it from TN. to NY. and back, 1150 miles each way and drove it non stop, just stopping for gas. The truck was flawless and did not use a drop of oil. I have seen many many other trucks from this 1999-06 era with the ls engines with 200,000 to 300,000 miles still running perfectly, is this quite common for these LS engines to run this long and not even use oil? I was a little nervous on this trip with the high mileage but it never missed a beat. wondering because i am looking at a few 5.3 engines right now, want to swap a 5.3 in as the 4.8 is a little underpowered and the 5.3's im looking at all have around 100,000 miles on them, but if they are known for running 200-300,000 miles, then 100,000 is still new and i wont hesitate to get one with 100,000 miles on it. Has to stay reliable as i travel some. I always thought these engines were known to burn oil but i havent seen that..
Thanks

 

LS engines are extremely Reliable. I would just keep driving it until the engine stops lol. Maybe buy a used 5.3L like you are looking at, and keep it in your garage until you need it one day.

 

99-00 are indestructible. That's why GM changed the plan.

 

so in my 5.3 hunting to swap in, i should look for a 1999-2000 also rather than a newer 5.3?

 

My 170k miles '00 5.3 uses MAYBE half a quart or so during a 6k mile oil change interval. And I think some of that is just what is sucked up through the PCV system into my catch can.

 

I've driven a couple of 00's into the high 100's and they were still going strong when I swapped them out. I only swapped them out because the 60's behind them gave up so I refreshed both the engine and trans at the same time. I have an 03 with about 160 that's still running strong but the trans is starting to show signs of its age so it'll be time for another swap soon I imagine

 

If you asked me, I'd tell you to keep your eyes open for a 2005-2006 L33 aluminum block 5.3 liter. They were the "H.O. 5.3" and have a 10:1 compression ratio, better heads(799 or 243), LS2 timing set, LS2 rods, LS7 lifters, etc. I found mine at a salvage yard for $900 complete.

All of your old stuff will bolt directly on.

 

the ls engines are great. i've seen way too many of these trucks flogged, abused and not maintained and almost every hard failure i've seen has been transmission or differential. it's rare to see a stock ls engine worn out or broken if it's been even somewhat maintained

 

Great idea. I completely forgot about those engines.

 

Yep these engines run forever, if maintained properly.

My pop has 280,xxx on his 5.3 and I have 194,xxx on my 5.3 and I'm still running stock tranny lol.