DIY - Transmission / Diff Fluid Change Reference Guide

[chicagokid]

Can someone please chime in on the Redline MT-90 75W-90 GL4 and Redline Shockproof mixed together? Is this good, bad, safe, ok to use for both diff and trans?? How is this compared to Gear 300?

[Crosscharge]

I switched out for the Motul300 this weekend.


Before I switched, it took about 3-5 mins of driving before shifting into 2nd became smooth.


So far (on a cold start) the very first shift into second is a bit rougher, 2nd shift is decent and the rest are nice and smooth.


This seem normal for some of you other guys? that noise of the first shift into second make me cringe everytime

[2point0]

Originally Posted by Crosscharge

I switched out for the Motul300 this weekend.


Before I switched, it took about 3-5 mins of driving before shifting into 2nd became smooth.


So far (on a cold start) the very first shift into second is a bit rougher, 2nd shift is decent and the rest are nice and smooth.


This seem normal for some of you other guys? that noise of the first shift into second make me cringe everytime

I wouldn't say it makes a nasty noise, but my experience is similar otherwise. On cold days, I need to shift a few times for it to smooth out the 1-2 or 2-1 shift.

[kodyo]

Can anyone comment on how often the trans/diff fluid should be changed? I changed about 14k miles ago and will be jacking up my car soon to finish my exhaust setup, is it worth changing diff/trans fluid at the same time or is it still too soon?

[2point0]

Originally Posted by kodyo

Can anyone comment on how often the trans/diff fluid should be changed?

I don't know offhand, but you can look up the maintenance schedule for your car. It's on Subaru's website somewhere. Just do a Google search for your year. Someone has probably uploaded it here, too.

[B-R-Z]

Originally Posted by kodyo

Can anyone comment on how often the trans/diff fluid should be changed? I changed about 14k miles ago and will be jacking up my car soon to finish my exhaust setup, is it worth changing diff/trans fluid at the same time or is it still too soon?

R=Replace
P=Perform
I=Inspect

[Fizz]

Originally Posted by kodyo

Can anyone comment on how often the trans/diff fluid should be changed? I changed about 14k miles ago and will be jacking up my car soon to finish my exhaust setup, is it worth changing diff/trans fluid at the same time or is it still too soon?

You probably don't really need to, but since you'll have easy access to it already might as well change at least the diff fluid. It's an easy and affordable maintenance that I'd do on a yearly basis anyway. Your trans fluid can stay on for awhile more.

[kodyo]

Thanks for the replies. I have a spreadsheet going of all my maintenance and thought mine only said inspect on both the trans/diff, so wasn't sure when to replace.

How does one inspect the diff/trans fluid anyways?

[2point0]

Originally Posted by kodyo

How does one inspect the diff/trans fluid anyways?

First, make sure the car is level. Each has a fill/inspect plug and a drain plug. The fill/inspect plug is higher up, the level of fluid should be right at or just below the bottom of the hole. It's a pain to check if you don't have tiny fingers. You can always just add a smidge until it starts coming back out, then you know it's full.

If replacing, always remove the top plug first, that way the air can rush in when you remove the bottom one. You'll get a steady stream instead of a gulp-gulp-splash-splash.

Filling is a pain. The Motul bottles have necks on them (doesn't look like it, but it pops out of the bottle) and they say you can fill with just that, but it's not easy to get the bottle high enough to actually pour while under the car. Rig up a hose so you don't have to be underneath, your back will thank you.

[krayzie]

Originally Posted by mav1178

Before/after:

Just FYI washer(s) for rear diff are the same size/thickness. Cheaper of the two is part # 1215710010, just buy two of those.

-alex

Yea when I got home and opened the bag, I was wondering what the difference is between the fill and drain washers for the differential. Why two part numbers with Subaru tho?

I got mine at the Toyota dealer, the Subaru part seems to have a more blue sheen to it on the metal, the Toyota part is just straight silver. Unless I'm seeing things.

[NissanGuy]

I put Motul 300LS in my '14 Monogram with like 320 miles on the odometer, didn't notice any difference. If anything it's now a tiny bit worse. Nowhere near as bad as my '13 BRZ was, though...

Maybe the later-production transmission came with better fluid? Or did I use the wrong fluid?

[cookiesowns]

Originally Posted by NissanGuy

I put Motul 300LS in my '14 Monogram with like 320 miles on the odometer, didn't notice any difference. If anything it's now a tiny bit worse. Nowhere near as bad as my '13 BRZ was, though...

Maybe the later-production transmission came with better fluid? Or did I use the wrong fluid?

The LS comes with additional additives? or friction modifiers for LSD's. I'm assuming clutch type.

Not necessary for our Torsen, and I'm under the impression that it's probably not good if not bad for the tranny.

[KrazieChryss]

Great DIY write up. Made it a lot easier for me to actually start doing DIY maintenance to my 86. Thank you!

[gutbomb]

Originally Posted by B-R-Z

R=Replace
P=Perform
I=Inspect

I know this post is from several months ago but where does this chart come from? I believe the section for inspecting the rear diff oil has the miles and kilometers backwards. Same for the A/C filter.