The best maintenance is preventative maintenance 

Customer came in today for a noise in the rear concern.

Using a mechanics stethoscope I pin pointed the noise to the rear diff and found no fluid in it.

Fluid has never been service, ever, and it is possible for gear oil to burn up and sludge up and reduce to nothing. Ask Ford. Their PTUs are notorious for eating gear oil

[OccamsAutomotiveRepair]

I continued to investigate this concern in other videos and later discovered the cause was the result of the driveshaft angle being too high.

When I installed mounted the driveshaft to the new rear diff I noticed the flange didn't sit flush. Using a drive shaft angle gauge from my Ford days I found the angle wasn't correct.

I sent the drive shaft off for inspection and they said it had a small bend. It was cheaper to replace the assembly.

We both agreed that something hit the shaft, which pissed off the pinion shaft in the rear diff causing excessive heat; which backed the fluid.

The customer did have 3rd party warranty and everything was covered for a $100 deductible

[Bradenprices]

This has never been opened up…
Except right before I started recording and drained most of it out!

[AndersonERockefeller]

Never in my life I've seen an empty differential without having a leak.

[trollingdirty]

I always pull that fill plug first. Want to make sure you can refill.

[stuntdriver]

Standard rear diff maintenance on most Japanese cars is 60k - your # must be off. I replaced rear diff fluid at 71k on a rear drive Lexus and it was full, fluid resembled a dark Carmel color. This diff obviously has something else going on. Maybe front seal leak ?

[scotta]

A good friend of mine is Subaru Mechanic. He tells me stories regularly regarding how many Subaru owners neglect the maintenance. And neglect the CVT maintenance, oil changes, coolant changes can be very costly. He also told me to never buy a used Subaru unless maintenance records can be tracked and proven. He also said that he wouldn't own one FWIW.

I over maintain our vehicles. Engine oil and filter every 6 months, differential service yearly, transmission service every 2 years, power steering fluid yearly, brake fluid every 2 years. Coolant flush every 4 years. Friends wait for us to trade cars so they can purchase our old one. We own our cars for over 10 years and the current car we own is 20 years old and runs like new. SAAB 9-5.

[jonathanshiflett]

This feels like sabotage because the fluid doesn’t just disappear from the differential it has to leak out or someone has to drain it for the fluid to disappear like that 😂

[eltsennestle]

Damn that evaporating diff fluid at 60, 000 miles.

[UNVME]

What a great shop/mechanic... never checked the customers fluids...

[FloridaRetirementScout]

I’d fire this Mechanic if I was his honest Boss.

[raymondcruz]

I blame the dealer. If the customer was taking his vehicle in for regular service, this should be caught on the vehicle inspections. Normally those sheets have a box for checking all fluids... someone wasn't checking the diff if it was topped off and saying it was checked.

[manny_the_weeb]

Checking diff fluid level is part of routine maintenance genius
Nice job boning over your customer they should find an actual shop that does real inspections

[dsRB]

If you buy a Subaru, you gotta do a lot of extra maintenance to keep it going, on literally every major component. Part of the problem is that differentials (Ford 9in, 8.8, Chrysler 8 3/4, name most old American rear ends) aren't made like they used to be, but Subarus were never made to last. Which is why I'll never buy a Subaru or anything Japanese. Junk

[Steve-wxgk]

Please just keep in mind that maintaining every system in your car is not common knowledge to everyone so please don’t make fun of them for not knowing.
I’m sure that might not have been your intention but I find a lot of mechanic videos do this.

[burtcale]

Never filled correctly at the factory and not inspected before delivery.

[waynegilchrist]

One of my early jobs as a teenager was changing oil and lube in a Chevrolet dealership. We always changed oil and filter, lubed all the steering joints, the universal joints, checked the rear-end oil and the transmission level and we checked brake fluid and coolant and washer levels as well. A job worth doing is worth doing right. I know vehicles have changed since the 60s but good service should include a through check-up of everything

[RedNineTeen]

Off topic but I just changed out the rear diff fluid to my 19 ram 1500 and it made me glad I did it after watching this

[timblackburne]

Think of all that money they saved, it should pay for half that diff replacement

[thegamepz]

They drained it, so they can rub it in his face “ you see you had to change your fluid “ seen that being done

[richkrstulovich]

Oil leaks not evaporates or someone emptied and did not refill.