So, I have hear this numerous times over the years. But.... When you buy a new car/truck/whatever off the lot it has no miles on it. You buy it, drive it off the lot and head down the freeway at 75mph and drive it home. No break in, no requirement to break in, etc. They function just fine. Why would you need to do this when you regear?

I don't dispute the importance of the installer looking at the wear after a period of time, to verify the install, but I question that break in method or at least the need for it.

Just curious

 

Factory gears are lapped and engines are run on the assembly line.

Special break in oil is used.

Still, your owners manual gives break in requirements for new vehicles--including max speed, restrictions on towing, etc. for early miles.

 

You potentially void your warranty if you don't follow new vehicle break in procedures.

 

Again, which almost no one ever follows. Have you ever seen anyone read the owners manual before they drive the car off the lot? I have never had a dealer tell me to do any kind of break in either. Have purchased in excess of 25 brand new vehicles in my life.


Not saying don't do this. Just playing devils advocate for some good discussion

 

And the dealer would be able to prove that one way or another how?



Geez I messed up my formatting in my last replay. I burined the responses in the quote. Woops

 

Obama will know with the help of the NSA!!

 

Of the all of cars, trucks, motorcycles, atvs, and even trailers I've purchased new, I've never had a dealer not remind me of the proper break-in procedures.

I even go beyond this with jeeps or Ram trucks. I go under the assumption that the dealer may have been sloppy on their PDI, or at the manufacturer and re-torque the suspension components.

Almost no one ever follows? People are stupid enough to buy a brand new vehicle and not follow break-in procedures?


Anyway, the factory gears are lapped so that the splintering/debris affect of the break-in is less. You get new aftermarket gears installed that haven't been lapped, and you will find the magnetic plug will have a good amount of material on it at your 500 mile differential fluid change after break-in.

This is easy to test yourself. If you have never changed your diff fluid, change it now and see how much debris there is on the magnetic drain plugs. Then, regear--following recommended break-in procedures--and change the diff oil at 500 miles and see how much debris there is on the magnetic drain plugs as a comparison.