Break-In Procedures Per Manual.....???

[SoCal Angler]

Preparing for first oil change at approx. 525 miles.  Would like to begin towing (2500# boat and/or TT at 8000#.  Below is copy/paste from my owner's manual RE:  break in procedures. 

 

2023 GMC Sierra 3500HD, 6.6L GAS, 4X4, Crew, Shortbed

 

At first I was interpreting it as during the first 500 miles no towing, after which towing would be allowed.  However, how much weight is allowed after 500 miles?  The highlighted sentence below states that gradual weight/load can be added as well as speed.  Not as precise a specification as my mind would like. 

 

So, at what miles..... are we supposed to gradually begin adding to tow weights/load/speeds?

 

Starting and Operating
New Vehicle Break-In
Caution
The vehicle does not need an elaborate
break-in. But it will perform better in the
long run if you follow these guidelines:
. Do not drive at any one constant
speed, fast or slow, for the first
800 km (500 mi). Do not make
full-throttle starts. Avoid downshifting
to brake or slow the vehicle.
. Avoid making hard stops for the first
300 km (200 mi) or so. During this
time the new brake linings are not yet
broken in. Hard stops with new linings
(Continued)

Caution (Continued)
can mean premature wear and earlier
replacement. Follow this breaking-in
guideline every time you get new
brake linings.
. Do not tow a trailer during break-in.
See Trailer Towing 0 272 for the trailer
towing capabilities of the vehicle and
more information.
Following break-in, engine speed and load
can be gradually increased.
On new vehicles, the various mechanical and
electrical systems experience a “break-in”
period during the first 6,400 km
(4,000 miles) of routine driving. As the
vehicle is driven, the mechanical systems
adjust to provide optimal fuel economy and
transmission shift performance.
Electrical systems will adapt and calibrate
during the break-in period. A one-time
occurrence of clicks and similar vehicle
noises is normal during this process.
Normal driving charges the vehicle’s battery
to achieve the best operation of the vehicle,
including fuel economy.

 

Under Towing section of manual:

 

Do not tow a trailer during the first
800 km (500 mi) of vehicle use to prevent
damage to the engine, axle, or other
parts.
. Perform the first oil change before heavy
towing.
. Do not drive over 800 km/h (50 mph) and
do not make starts at full throttle during
the first 800 km (500 mi) of trailer
towing.

Edited September 5, 2023 by SoCal Angler

[64BAwagon]

My 2021 only had 350 miles on it when I left on a trip to FL with our 12k fifth wheel. I never saw any adverse effects. I changed the gear oil in the rear diff at about 4k miles and it looked normal with no excess wear. 

No one that drives these vehicles before you buy it babies them. Other than YOU not beating on it for the first 500 miles I would just use it for what you bought it for. 

BTW, I just passed 500 miles on my 2024 and the brakes are just now getting where they feel normal. 

Edited September 5, 2023 by 64BAwagon

[Grumpy Bear]

6 hours ago, SoCal Angler said:

So, at what miles..... are we supposed to gradually begin adding to tow weights/load/speeds?

 

Told this story before so the truncated version. I knew a guy who NEVER changed his oil or even the short factory supplied oil filter. Never looked at the ATF or Diff fluid. Never washed or cleaned. Added oil if it didn't register on the stick and air in the tires only if flat. Beat it like a whelp pup. He ran that thing over 125K miles. Then junked it. And it was indeed junk. 

 

Some would say he saved allot of money. Did he? He bought a new car. Half that money spent on maintenance would double his vehicles useful life. 

 

I've known fellas all my life that do next to nothing for maintenance and get her to go even 200K. But I have NEVER known a fella to do next to nothing make it over a half million or more. I've known a few to go a million or darn close to it. 

 

Break in is something like that. Don't do it and often you will never know the difference over the 100K or less most keep a car. Don't do it and long hauls you will not do. 

 

Your manual told you when. You cut a pasted it. 4K miles to break it in fully. 500 before you haul with it. Change fluids before you do. Drive it like an adult. A mature one not a 50-year-old teenager. Make good choices. It will reward you more times the it doesn't. 

[KARNUT]

It’s great I guess if you have the luxury of breaking your work trucks in. I didn’t. I would get the fifth wheel ball in one day be hauling the next. Even my work 1/2 tons would get their tool box, fuel tank, air compressor and hit the highway. All my vehicles were bought off the lot and test driven hard. All had exhaust modifications. And some went to my ROW crews after I was done with them. I wanted a new one after 150K miles, about 21/2 to 3 years. Only 1 engine failure in 40 years. Replaced under warranty, a factory defect. I can say with all my vehicles since 1974 I drove them hard from day one. My very first 73 Mazda RX3. I didn’t even have my license yet. My father drove it home with me and my brother. My mother was following in a 73 Buick Riviera. The first light he had a race. The rest of the night several uncles and cousins had a go with it. I learned how to flat shift that night. Every one in my family had performance cars. Should you follow break in procedures? Probably with the stuff they put out today. 

[ssgballistics]

I think your awareness and caution are going to ensure that you have many worry free miles. After that first oil change, I’d think you are good to tow your boat without looking back. 2500# is nothing for that truck. You’re probably good for the TT at that point too, but you could wait a couple hundred more miles if it helps you sleep better. Like grumpy bear said, just drive like an adult and you’ll be good to go. 

[Dunn]

 Never tripped on stuff like that.....used common sense and change oil when it was time

 

Since 1983 I've never had a motor problem with a truck

 

They really aren't that fragile.....HD trucks are built for work

 

Just run it and be sensible

 

Can't imagine Fleet guys are babying their trucks for 1000 miles b4  putting some serious work loads on em

[Grumpy Bear]

4 hours ago, KARNUT said:

I wanted a new one after 150K miles,

 

Isn't this the point I made? Set that bar low enough and you can do anything you like. 

[Grumpy Bear]

3 hours ago, Dunn said:

 1.) Never tripped on stuff like that.....used common sense and change oil when it was time

 

2.) Since 1983 I've never had a motor problem with a truck

 

3.) They really aren't that fragile.....HD trucks are built for work

 

Just run it and be sensible

 

4.) Can't imagine Fleet guys are babying their trucks for 1000 miles b4  putting some serious work loads on em

 

1.) When was it time? Point of reference for this statement is pivotal. 

 

2.) How many is that and how many miles each, average. a.k.a how low has the bar been set. 

 

3.) From GM Service Bulletin No.: 06-06-01-007H. It's a very low bar for a diesel. (below) 

 

Duramax™ Life Expectancy The Duramax™ 6.6L V8 Turbo Diesel Engine is sold with a warranty of 100,000 miles/160,000 kilometers. The Duramax™ has been tested to survive upwards of 200,000 miles/320,000 kilometers. The Duramax™ powertrain is designed for reliability, peak horsepower and torque within its design limits......

 

Point to my last two post is POINTS OF REFERENCE. Not looking to pick a fight. But guys, if 150K is what you think a high bar is then do as you please. It will not have much impact on anything over such low expectations. 

 

 

[nards444]

Engines do not need break in periods like they used to, even te manual says so.  To me there is some common sense, give everything a few miles then have at it.  A lot of old wives tales out there, same goes for the 3k oil change, there is nothing from manufacture, experts, oil experrts to point to this,  but you still have the peace of mind guys out there.

 

GM has an interest in ensuring these things are good for 100-150k,  on average people are getting new cars around 7-8 years or around 100-120k miles.  Me personally Im not going past 50-60k much less 100k,  for me its the next guys problem. 

[KARNUT]

5 hours ago, Grumpy Bear said:

 

Isn't this the point I made? Set that bar low enough and you can do anything you like. 

Better than half of my trucks and cars were handed off to employees or family members. I’m not really arguing against breaking in. In my reality it wasn’t possible. I didn’t see any vehicles fail because of it. And you’re right that’s my reality. I bet north of I-20 rust takes out most vehicles. Mostly the desire for a new one. My grandparents wore everything out before a new purchase. How many people up north have winter cars? I have four for different driving moods and applications. We are all wasteful. And probably all right. Your statement is right on.

[64BAwagon]

I am not arguing against taking it a little easy on a new vehicle, I am saying that if you do you will likely be the very first one that sits in that vehicle that has. Spend some time around an assembly plant and transport yard and you'll see quickly just how hard these vehicles are handled prior to retail delivery. 

[garagerog]

Everyone has their own opinion of proper break-in procedures so I might as well throw my hat in the ring. In light duty applications such as cars and 1/2 ton p/u's, I believe brakes are the most important. In HD applications, probably the ring and pinion gears thus the warning on early heavy towing. UOA's on the factory oil will show heavy concentrations of iron and copper, so that first oil change being early probably isn't a bad idea, and one can sleep better at night if you're worried about factory cooties.

Edited September 6, 2023 by garagerog

[Grumpy Bear]

On 9/6/2023 at 7:55 AM, 64BAwagon said:

I am not arguing against taking it a little easy on a new vehicle, I am saying that if you do you will likely be the very first one that sits in that vehicle that has. Spend some time around an assembly plant and transport yard and you'll see quickly just how hard these vehicles are handled prior to retail delivery. 

 

Oh, I get that. Had a Dealership valet doing smokey 100-yard burnouts with my 98 5.0 while in for service. 

 

When GM designed the first SBC the rods were built to take 110% of designed load at 6K rpm for one million cycles. It was considered infinite life. But what does it mean? 

 

When you put tension on a material there is a degree of load that can be applied that will not stretch the part. You can load and unload that degree of tension infinitely without failure. Add a bit more load and the material will stretch under load and when the load is removed the part will shrink back to the original dimension. Do it long enough and the part will fail. GM put a load on those rods 10% past the elastic onset and back one million times without a failure. How many cycles and how wide that load tension that material can do this depends on the material and level of conditioning or treatment. Take the load past that point, plastic deformation, and it deforms permanently and a short walk down the load path after that, it breaks. A similar thing happens with wear, the rubbing kind. The Strebeck Curve depends on LOAD, viscosity and velocity and viscosity depends on temperature as well a shear (velocity).

 

What's the point? You can't see any of this happening and for most of either cycle it depends on the number of cycles and the degree of stress. Simpler? It's not that you can't get knocked out with a single punch, but a bunch of less powerful punches will do the same thing.... eventually. It is rarely the haymaker (single or short cycle event) but the punches in bunches that wear it out or break it. 

 

Stock car motors should teach this and yet the lesson is lost. Best parts in the world running the best fluids possible broke in on a dyno will not last a million miles. Rarely make it past 1,000. 

 

 

Edited September 7, 2023 by Grumpy Bear

[Another JR]

Not 10% past their yield load - 10% past their design load. At least that’s what it says. They still would have been below the fatigue limit (endurance limit) at the critical location if they designed it right because that would be one of the constraints that set the design. I assume that was what they were intending to demonstrate. 

 

Edited September 6, 2023 by Another JR

[nards444]

5 hours ago, KARNUT said:

Better than half of my trucks and cars were handed off to employees or family members. I’m not really arguing against breaking in. In my reality it wasn’t possible. I didn’t see any vehicles fail because of it. And you’re right that’s my reality. I bet north of I-20 rust takes out most vehicles. Mostly the desire for a new one. My grandparents wore everything out before a new purchase. How many people up north have winter cars? I have four for different driving moods and applications. We are all wasteful. And probably all right. Your statement is right on.

 

 

Thats the reality up here with salt.  Your just not getting more than 12-15 years before its rotted out, which is anywhere from 150-300k miles.  There are some outliers where the old man grocery gitter is still alive and the few hoopties driving around, in general most are ditching cars around 10 year mark.