Replacing Differential Fluids

Hey all,

I have a 2012 Subaru 2.5i Premium with 42k miles. I just made an appointment for a full synthetic oil change, and a brake fluid exchange. Someone mentioned to me that I should have my differential fluids replaced at this time. Is that really necessary? I’ve had several people tell me you can go 60-90k before needing that done. I guess it all depends on the condition of the diff fluids, but at what mileage what you all recommend it? What mileage do most people usually get this done at, and what is the longest you’d push it (mileage wise) in the Midwest?

I am debating if I should add that service as well (should probably just do it), but wanted to make sure I really need it.

Thanks all!

What does your owner’s manual say? Why don’t you trust what the manufacturer tells you to do?

@lion9car–This OP stated in one of their other threads they did not know if they had a spare tire so why would you expect them to read the manual?

Ok, d$ck! Sorry we are not all as perfect as you! Screw this forum!

More important is the transmission fluid change.

Today, most manufacturers do NOT recommend changing the transmission fluid or the diff fluid. But most people recommend you change them periodically. The interval usually listed is between 30k and 60k.


Wouldnt hurt to do it,at least you know the level is right,make sure you use what the manu says.(we are hard to offend)

Y’know, Jman, I was going to answer your question, but your 7:30 post left me feeling that you don’t deserve an answer. I for one am happy to see you leaving this forum.

Thanks mountain bike! Just because of your nice comment, maybe I’ll stick around awhile!

I change the rear diff fluid in my truck about every 50K. Or whenever the seal leaks and I need to replace it. Or whenever I drive the truck in deep enough water to come up to the differential. But my truck is 40+ years old, so your vehicle may have differing requirements.

“If you can’t stand the heat, get out of the kitchen.”

If you do any towing, or if you carry bikes and/or kayaks in a roof top carrier then you are putting a lot more stress on the differentials and that shortens the change interval. For normal service I think most cars are good for 80 to 100K miles, but frequent towing drops the interval down to 30K in a Toyota Sequoia. Better safe than sorry. Transfer cases, and differentials aren’t cheap to repair or replace.

I would check the owner’s manual. But reading the manual for my '01 Toyota Sequoia was just so confusing on differential fluid service that I can see why the OP is asking the question.

Honda CRV are very fussy about what fluids go into the differential and transfer cases, so I’d stick with Honda fluids. Subaru’s I’m not so sure about, but make very sure you get the right spec and a good quality fluid in there.

Jman136 wrote:
Sorry we are not all as perfect as you!

You really don’t get it, do you? The people who designed, built, and tested your car gave you instructions for maintaining it properly. However, for some reason, you apparently prefer to do whatever “someone” and “several people” say. We’re asking you why. If you can’t handle that question, you are better off somewhere else.

I would lean towards doing the first change sooner, then longer intervals after that.
New gears etc. tend to shed more particles into the oil during break in.
All the times I’ve changed oil in manual transmissions the oil looks “dirtier” at that first change than later.

The OP has a legit q and manual is rather useless in this case with Subaru. It states inspect every 30k miles that is all not replace.

Having owned Subaru currently when free Subaru point paid for service visits 0k-120k I did it every 30k. I have not changed the fluid since 120k and now have 190k with no ill effects. The Subie guy said it was getting dirty but said not iminent in my car that is in repair only as needed and change oil state for the rest of its days.