Pretty interesting data/opinions. After going through the Break-in debate for a new motorcycle engines it was amazing that there is the same debate for new trucks.

Just for curiosity I looked up "Differential Break-in" on google and got some info, again several different versions but it seems like most Gear Manufactures do give some guidance. Three sites that provide some data:

https://www.ringpinion.com/Technical...r_break-in.inc

New Gear Break-In Procedure

https://ls1tech.com/forums/gears-axl...procedure.html

While there is some disparity in their data, all three have the same basic guidance for the first couple hundred miles, and first time towing.

Ford's Break-in mileage is about double what the above posts recommend so as mentioned earlier in the posts, it may also include brakes, engine, CYA, etc.

Not disputing anyone's posts, just thought it is some interesting data.

 

What I find interesting is that ford does not reccomend an initial diffferential fluid change, whereas all differential shops will tell you to change the fluid after the break-in period. I changed mine at 2,500 miles when I installed a large capacity rear diff cover. It was black and had small metallic particles (like metal dust) in it. I refilled with Amsoil 85-140 severe gear oil.

 

So the, "Drive it like you stole it" break-in procedure is no longer advised?

 

LOL. When I bought my new bike the Kawasaki dealer/salesman explained the Kaw break-in period and instructions, then immediately said "now that we have told you the Kaw recommendations" we recommend you drive it easy for the first 15 miles then drive it like you stole it, but fluctuate throttle and let it cool down after 20 minutes for the first 50 miles. Additionally, they stated that I should make sure to perform a couple of heavy load high RPM runs to seat the piston rings. Then change the fluids at 50 miles, but don't switch to synthetic oil until after 300 miles. Supposedly the Synthetic oil is to slippery and doesn't allow everything to wear and seat properly during break-in which will allow the engine to burn oil from then on.

I don't know the actual validity of their recommendation, but I followed it and the bike runs like a top and doesn't burn an ounce of oil.

As far as my new truck break-in (when I get it) I plan on following the differential break-in links I posted above then normal use with only light towing if needed until 750 - 1000 miles. Then complete fluid change before normal full capacity use.

 

Always amazes me that some two bit salesman thinks they know more than the guy that has a master's degree in mechanical engineering and designed the engine....

 

The problem is you do not know who is making the procedures now days...
Engineer
Marketing
Lawyers
or
Bean counter.

 

forgot example

Pontiac transmissions...
Started with 1999 Bonneville SSEi (supercharged) transmissions, 40-60k with super charger, aluminum in transmission.
Same drive train in later Grand Prix with super charger, same trans same issue. Aluminum in the system. Claim was that a steel part was replaced with a aluminum part and in that mileage range issues occurred.
I had actually told the dealership when we bought it, between 40-60k I would be back for the replacement trans. 46k later... We were waiting 3 weeks for GM to look at the trans to figure out what went wrong.
Do not think the engineers signed off on that one, if that was the case.

 

They probably all had a part to play in it. 1) engineer writes spec based on their understanding of metallurgy and what's needed for adaquate reliability 2) bean counter look at warranty claims and determine there likely will be some savings as a result 3) lawyers review and approve language 4) marketing signs off that no implications of poor quality can be construed from language.


I worked for a large multi-national oil company for 40 years in the corporate offices and saw this kind of thing every day😜

 

The break-in period for a differential is extremely important and should be heeded wisely. This is because the ring/pinion need to wear in together and heavy loads should be avoided. Damage can be caused if excess stress occurs prior to this melding relationship.

This info comes from Jim Allen; a renowned auto writer and author of this book:
https://www.goodreads.com/book/show/....Differentials
I'm not putting it up here so you'll buy it; although it's a great read and I do have a signed copy from Jim (a friend).
I only link this to show his credentials, and how his opinion is probably a lot more factual than any bench racer here. If you google his name, he's written articles on drive-trains (mostly diff) for all manner of auto mags, often focusing on 4x4 applications and off-roading. He also dabble in filters a bit, but his penchant is diffs. He collaborates with Randy Lyman of Randy's Ring and Pinion fame.


That being said, I don't know that the OP ruined his diff with the light loads he towed. But it's generally to be avoided, per people with great insight into the topic.

 

I'm not trying to slam you here but... I work for a large excavating and grading company with a fleet of trucks and all of the equipment and large trucks (dump trucks and semi's) are maintained on a schedule based on engine hours. But the pickups on the other hand.
The pickups get the oil changed when we have time or when the guys remember. I would say that some of the trucks get the oil changed a couple times a year at best and they get driven upwards of a thousand miles a week. As for the rest of the fluids they will never get changed over the life of the truck. We have had a few pickups with well over 300,000 miles of construction abuse. I can tell that we have never had a differential fail in any of our pickups, a few transmissions have failed and a few engine problems but mostly minor problems. Most if not all of our trucks are pulling heavy trailers with a full load of tools in the bed of the truck within a few days of delivery. My boss even pulled a trailer with a skidloader on it to the dealership with his old truck, unhooked the trailer, hooked it to his new truck and drove away. If we can't break these trucks you guys are fine! We probably haul more weight in the boxes of our trucks than some of you guys tow. I know what the owners manual says but in the real wold this is what happens. Drive it like you stole it!

 

Lawyers have got everything more complicated

 

I am always amazed at this too. And not just on trucks and cars. And not just salespeople, sometimes it's people who know even less.

 

^^^^^^^BINGO!!!!!!!! This is exactly what I have been saying for a long time!!!
What about all the commercial/industrial applications??? The rigs are purchased to WORK!!!! Not sit around and get babied!!!!

 

I don't necessarily buy everything I read in the owner's manuals, written by the "engineers." Do you know how many transmissions have failed because the *book* says the fluid and filter are "lifetime" and never need to be changed?

If diff break-in is so critical, why not have the manufacturer break them in on the assembly line before shipping? And then change the fluid?

I don't think diff failure is very common. Maybe among the rock crawling set installing 44" tires on a Wrangler with stock axles, but not in the realm of heavy duty pickups.

 

Is this the Jim Allen of Land Rover driving fame? I bought his book "4 wheeler's Bible" years ago and it is a great read if you are interested in off-road driving of all makes and models. The book also clearly explains how differentials work and the differences between open, locking, and limited slip. Most people don't grasp how a differential really operates and what the differences are.