How often do you change your differential oil?

When I bought my 2003 Kountry Star I immediately changed all fluids to full synthetic, engine oil every 5K real differential at 2K now have 118,775 on coach and have never changed out the rear again. Of all vehicles that I have owned I never change out rear fluid except to synthetic to replace dino gear oil, I am 70 years old and have never had a differential service problem NEVER. Do as you will, that's my story.

According to Freightliner the synthetic gear lube SHOULD be changed every three years. I don't know what the other manufacturer's requirements are.

BobGed wrote:
According to Freightliner the synthetic gear lube SHOULD be changed every three years. I don't know what the other manufacturer's requirements are.

Of course, most trucks are putting on close to 400,000 miles in those 3 years too.

Replaced mine with synthetic at 4 years 4 month old.
Next time was 13 years 2 months later(Feb. 2015). Fluid looked like it was just put in.
Replaced with Mobil 1 75-90W synthetic and that will be the last time it will be done by me.

I purchased mine used last year with zero service records. It had 65k on it and I'm sure it was never changed. Changed it this year looked like new also. Not sure when I will change it again. Hate that smell.

I have never changed it in any vehicle.

mike brez wrote:
I purchased mine used last year with zero service records. It had 65k on it and I'm sure it was never changed. Changed it this year looked like new also. Not sure when I will change it again. Hate that smell.

CC tech support says to change it at 100K miles.....

I think it depends on how you change it and how much metal is in the oil. I change mine when I change the fluid in the transmission every 30k miles. My drain and fill port is on the top. I think the best way is to split the case drain and wipe down the inside then reseal and fill the housing. Mine did not leak nor did I want to cause a leak so I just pumped it out and refilled. No noticeable metal in the fluid so I probably wont change it again but my transmission still shows metal on the magnet so I will continue to change every 30k miles. To me it is more about inspecting than the fluids breaking down.

Starting this year, after having to replace the ring and pinion, I am changing it at new intervals because of the condensation that builds up when they sit. I have decided to change it at least once per year. For the first three years I owned it, I did not even check on it. I had heard that condensation could build up, but did not realize the degree of damage that this can cause.

I know there is synthetic oil in mine but not sure when it was changed. I am going to change it anyway so I can record the age and mileage of when it is done.
It is a simple job ( on mine ) and only uses a couple of quarts so not a big deal or expense.
Another step on preventive maintenance.