Long term reliability of GM 8.1 Liter

I didn't have good luck with 8.1 service trucks at work. The first one was a 2002 with 42k miles, used excessive oil like mentioned, 5.0 mpg on the best day and I couldn't keep it out of the shop. It left me stranded a few times. The second one was reliable (36k miles) but 5.5 mpg on the best day and it also used oil. I used to tell anyone who borrowed it to fill it with oil and check the gas! Craig

Dick B's 6.0L will last 500k miles at it never sees over 3000rpm ;). That 6.0L (and 8.1L) has hundreds of thousands in the last 15 years with over 100k miles.

More silicon, but only up to some percentage (forgot, but around 10%) and makes
it stronger.

Key is that is more thermally stable than the other aluminum alloys. Meaning it
won't increase in size in an iron block as would a regular alu alloy...meaning
that the designers can size it with less tolerance

Silicon readily melts and is absorbed by the aluminum during the process, so it
allows the designer to play with the crystalline phases during processing. Meaning
harder and lower co-efficient of expansion to allow tighter tolerances

The piston slap does have to do with expansion, but not the aluminum alloy itself,
but the coating on the piston

Piston slap was worrisome because it sounds like a rod knock

The oil consumption has to do with the harder piston rings mentioned in another
thread. That is an extension from my Suburban forum a few years ago. Some have
found that it takes 20K or more before the 8.1L full seats the rings...a very good
indication of longevity...if taken care of

I have the 7.4L big block...gen before the 8.1L. I'd LOVE to have a GMT800 with
an 8.1L, but with the way things are going with new...will keep mine till the
wheels fall off, or won't fix it anymore...or if a 8.1L crosses my path and can't
pass up that deal

These are TRUCKS.

Designed for work and much more to them than a 'car'. To last much
longer 'working' than any or most any car.

If the OP does get a full sized SUV with a 8.1L...first thing is to replace
the OEM receiver with a traditional design

Mine turned 163k this week towing the 9k TT to FL. Piston slap was found to be tales of the Internet. The engine uses some kind of hypereutectic (Ben help me here) piston design that makes them noisy on a cold start. Also uses about 1Qt of oil every 3k miles.

Agree with peeps on the anvil comment....I've fixed about everything else on this truck except the motor...

Even the ones that had the piston slap rarely failed.

Longevity does NOT happen by itself...

Depends on how it is taken care of (quality of materials and service schedule),
where it is driven (terrain), how much it is forced to tow and the biggie...the
right foot

All of today's ICE's can last many times longer than when I first started driving
When everyone was thinking of replacement at around 100K miles

Again, key is how it has been taken care of...of course there are lemons out
there and will be in the future...

My brother recently sold a '03 8.1 with 384,000 miles on it. Engine and tranny had never been touched, except for good maintenance. It did quite a bit of towing and lived in the oil field for 3 years or so.

Dick_B wrote:
We had at least 100K on our 2003. But my question is will my current 6.0L make it that far?

Yes, I have a break down of sales figures(somewhere). 64 percent of GM's HD sales are 6.0 trucks. There are many out there with or close to over 200,000 miles on them. Lots of them in fleet service. The two guys I camp with have 6.0 trucks with heavy towing. One has 170,000 on his truck the other has 185,000.

Having said that the 8.1 is a beast when I bought my truck I was looking for a good used truck, but I got such a sweet deal on the 6.0 I have I could not say no.

As far longevity based off what I see on the GM board you can't go wrong. Plus I the truck platform you get the Allison. What is not like.

We had at least 100K on our 2003. But my question is will my current 6.0L make it that far?

colliehauler wrote:
Great motor just thirsty. Will pass everything but a gas station.

Yep. Nothing more fun than being able to accelerate up a steep grade.