Subaru Owners, which diff fluid viscosity do you use?

[Wheel366]

I have a 2018 Legacy Sport and a 2019 Impreza Sport. Both call for Extra MT which is a 75W-80. There is a TSB to change the rear to 75W-90 due to a potential whining noise.

What I am curious about is whether fellow Subaru owners are going to 75W-90 or using say a 75W-85. I already had my Legacy done around 59k but my Impreza is about 6 years old with 30k and was going to have it done. Trying to decide what to go with. Any suggestions are welcome. For the record, I would have both the front and rear done with whatever I decide and not do 2 separate fluids.

As a side not, I called today to inquire about a CVT fluid drain and fill and was quoted $500. Also crapped myself. I was told there is no such thing as a drain and fill anymore. They need to hook up to the computer for correct temp (that I knew) but also need to reprogram the CTV after which I didn't know and am not sure I believe but this service rep has always been straight with me, so my doubt isn't because of her.

 

[Slick3914]

I run 75W-90 Valvoline in my 2017 Outback. Recently paid $360 at the dealer for CVT drain & fill (7 quarts) as reference.

 

[D60]

I have a 2018 Legacy Sport and a 2019 Impreza Sport. Both call for Extra MT which is a 75W-80. There is a TSB to change the rear to 75W-90 due to a potential whining noise.

What I am curious about is whether fellow Subaru owners are going to 75W-90 or using say a 75W-85. I already had my Legacy done around 59k but my Impreza is about 6 years old with 30k and was going to have it done. Trying to decide what to go with. Any suggestions are welcome. For the record, I would have both the front and rear done with whatever I decide and not do 2 separate fluids.

As a side not, I called today to inquire about a CVT fluid drain and fill and was quoted $500. Also crapped myself. I was told there is no such thing as a drain and fill anymore. They need to hook up to the computer for correct temp (that I knew) but also need to reprogram the CTV after which I didn't know and am not sure I believe but this service rep has always been straight with me, so my doubt isn't because of her.

The relearn feels a bit like the Emporer's Clothes: it pauses for a second, pretends to think and Voila!

I did it w my Otofix and Mr Subaru shows it at the end of one of his vids with whatever scan tool he was hawking. My understanding is that it's optional if you don't have prior complaints with performance

 

[Jimmy_Russells]

Everything I’ve seen and read says 75w90, never heard of anything else. I have three quarts in the garage ready for my wife’s Forester.

 

[aba4430]

Gear oils in our Subaru’s are as follows:

1. 87 Brat: Non-synthetic GL-5 80W-90 in the front transaxle and rear differential; presently Valvoline in it.
2. 2017 Subaru Outback Premium (2.5 l): Mobil 1 75W-90LS GL-5 in front and rear differentials.
3. 2018 Subaru Crosstrek with 6-speed: Mobil 1 75W-90LS GL-5 in the transaxle and rear differential.
4. 21 Crosstrek Sport: Same as the 17 OB above.

All vehicles are happy.

 

[Glenda W.]

75W90

 

[ChiTDI]

75w90 133k no issues. 2014 Outback

 

[BHopkins]

I always used M1 75W-90 in both the front and rear diff's in my wife's '13 Outback. I wasn't aware of any TSB, but the Service Manual showed that 90, 85W, 80W, or 75W-90 were all acceptable, depending upon operating temperature, with 75W-90 covering the greatest temperature range. It always worked well for me.

I always did my own spill and fill on the CVT, so I'm not sure what a fair price is at a dealership. But filling it by temperature, and doing a relearn are really no big deal. They are going to hook up a diagnostic tool to read fluid temperature, to get proper fill level. And since the diagnostic tool is already plugged in, it only takes about 3 minutes to do a CVT relearn. And that is allowing 1 minute to get to the proper menu in the scan tool.

 

[The Critic]

Extra MT is factory fill for many Subaru differentials but is unavailable in the US. 75W90 is the alternative.

Viscosity of Extra MT is significantly lower than 75W90.

 

[Nuclear_42]

3 years and 20k miles so far on Amsoil Signature 75w-90 on my 21 Outback. No issues so far. Zero whine.

 

[nthach]

75W-90 “synthetic”.

 

[Wheel366]

Thanks all. I didn't want to mention brand but it looks like 75W-90 is the consensus. The 2 brands I have been considering are either HPL or Amsoil SVG.

I'll probably go with SVG with my preferred pricing and no other particular reason.

 

[GSCJR]

80w-90 in my Subaru driveline.

 

[THORROMIG]

75W90 Valvoline Synpower -- front & rear of Wifes 2017 Outback

 

[slacktide_bitog]

the cheapest 75w90 synthetic

 

[SubieRubyRoo]

Thanks all. I didn't want to mention brand but it looks like 75W-90 is the consensus. The 2 brands I have been considering are either HPL or Amsoil SVG.

I'll probably go with SVG with my preferred pricing and no other particular reason.

Amsoil SVG is a great gear oil and choice for Subaru (or any, really!) diffs. Just ask @Pablo!

Can’t go wrong with either choice.

 

[Rhill]

I have a 2018 Legacy Sport and a 2019 Impreza Sport. Both call for Extra MT which is a 75W-80. There is a TSB to change the rear to 75W-90 due to a potential whining noise.

What I am curious about is whether fellow Subaru owners are going to 75W-90 or using say a 75W-85. I already had my Legacy done around 59k but my Impreza is about 6 years old with 30k and was going to have it done. Trying to decide what to go with. Any suggestions are welcome. For the record, I would have both the front and rear done with whatever I decide and not do 2 separate fluids.

As a side not, I called today to inquire about a CVT fluid drain and fill and was quoted $500. Also crapped myself. I was told there is no such thing as a drain and fill anymore. They need to hook up to the computer for correct temp (that I knew) but also need to reprogram the CTV after which I didn't know and am not sure I believe but this service rep has always been straight with me, so my doubt isn't because of her.

I use 75w90. I doubt you'd notice any change in MPG, but it's a good robust fluid in gl5 trim. Easy to find everywhere. These diffs aren't terribly picky

 

[Clarkbug]

To add in here (a little late) I am running Motul Motylgear 75w-80 in my 2014 Forester with the 6MT. Its shared diff/transmission oil so using something thicker wont impact the shift quality the way it would for me.

 

[Impatient]

Many Subaru people use the Motul Gear 300, which is thinner than most, though still up to GL5 specs and does quite well in this comparison LAB TEST SubyRubyRoo commissioned (see below). I chose to go with the Amsoil SVG in my newer ‘13 Outback, but zero complaints with the Motul in my 07 Outback…which gets some spirited runs with its Turbo motor. Let’s not talk about the transmission here, since you have CVT’s, which I don’t have. I didn’t know Subaru went with thinner oils nowadays, so a 75w85 from Amsoil or HPL might make perfect sense.

FWIW, I changed engine oil, ATF, and the diffs’ oil in my ‘13 3.6 auto, and am now getting noticeable worse gas mileage…not sure which is the culprit, if any of these are. Might be something different, but fuel economy might be a good reason to try the Motul or a thinner HPL or Amsoil. Of the other 75w90’s, in the comparison lab test, I gave “points” to the thinner options (Motul and Amsoil). Notice, the Subaru HP sheared down to lower 13’s cst in the KRL column (13.5% shear from the virgin 15.34), so it’s practically a 75w85 anyway…so maybe that’s a 3rd or 4th option.

 

[2dogs]

75W-90 Schaeffers diff oil in my almost 10 year old, 100k Forester. I've changed the diff oil 3 times in the cars life.