Subaru BRZ rear diff with LSD; what fluid?

[zeroptzero]

Differential Gear Oil LX - What to Replace it With in Aftermarket - Subaru BRZ rear diff with LSD

I tried searching for what a Differential Gear Oil LX is but I could not find much about it. This is listed in the Subaru manual for the rear diff of a Subaru BRZ, as the factory fill.

It says you can use 75w85 or 75w90 if needed, but you might experience noise and vibration and worse fuel economy. I don't mind worse fuel economy but no one wants more vibration or noise ? I suspect differential gear oil LX might be thinner than aftermarket 75w85 or 75w90, but I don't really see any specs on LX fluids ? The rear diff is different from the transmission, it has an LSD.

Any suggestions on what might be an improved fluid for the rear differential, if the OEM fluid is best to keep as LX then I will stick with that, but I was thinking of using Amsoil or Redline. The LX term is throwing me off a bit. Thanks for any replies.

 

[slacktide_bitog]

Redline makes a 75w85 GL5 gear oil that should work in your BRZ. Since you're already using Redline for the transmission, there is nothing wrong with using their gear oil for the diff, either

The "LX" is probably just their name for their OEM gear oil used in the BRZ.

You don't have to use any specific brand name. Any 75w85 or 75w90 GL5 gear oil on the shelf will be fine.

 

[JavierH19]

Seems to have been covered on here. Don't see why motul gear 300 ls wouldn't work.

https://www.gt86.org.uk/forums/forums/topic/4618-gear-diff-oil/

https://www.fcpeuro.com/products/ge...TvklB4TOHaAPVSXWvHHeOn-saAtzTEALw_wcB#fitment

 

[zeroptzero]

^ Thanks for the replies, I wonder if LX is intended to be a lighter weight gear oil to promote fuel efficiency. I don't know why aftermarket fluids would cause noise and vibration if the OEM fluid is thin for fuel efficiency.

I was considering Amsoil and Redline as they are easy to get in my area, Motul might work too , I will search them all and find one that fits the application. I appreciate the replies. Thanks !

 

[VolkswagenFox21]

I'm using Redline GL-5 75w90 in my FRS's diff for a couple of years now. No discernable difference in fuel economy and certainly no increase in noise or vibrations. My guess is that the text in the owner's manual is copy and pasted from other Subaru models with a clutch type LSD, which can chatter, shudder and make noises when locking up. And it looks like they're warning that using a different weight fluid may have an effect on those things. But all FRS/86/BRZ use Torsen LSDs so that doesn't really apply to our cars.

These cars seem to be pretty happy with any 75w85 or 75w90 GL-5 diff oil. Amsoil, Redline and Motul are all very popular choices for these cars.

 

[zeroptzero]

I'm using Redline GL-5 75w90 in my FRS's diff for a couple of years now. No discernable difference in fuel economy and certainly no increase in noise or vibrations. My guess is that the text in the owner's manual is copy and pasted from other Subaru models with a clutch type LSD, which can chatter, shudder and make noises when locking up. And it looks like they're warning that using a different weight fluid may have an effect on those things. But all FRS/86/BRZ use Torsen LSDs so that doesn't really apply to our cars.

These cars seem to be pretty happy with any 75w85 or 75w90 GL-5 diff oil. Amsoil, Redline and Motul are all very popular choices for these cars.

Thanks for the reply on this, nice to hear a real world experience with the fluid and this vehicle. Good point about the LSD and I think you are right on that, that makes perfect sense now, and I agree it makes no sense that extra noise or vibration would be caused on a Torsen LSD. Thanks for mentioning this. I appreciate the reply .

 

[BISCUT]

Not sure if it is the same as my 17 3.6 limited diff. I had good results with Valvoline 75-90 and the squirt bags over plastic bottle are a plus.

 

[zeroptzero]

I dumped the factory fluid this evening, and I have ordered 2 quarts of Redline 75w90 for the replacement fluid. The OEM looked like it was pretty decent quality, it was a reddish colour, it flowed out pretty well. The drain plug had a lot of dark black metal paste on it, I was surprised by the amount given the low miles on the unit and fluid. That gave me reason to go with 75w90 over 75w85, I will go with a bit more viscosity vs fuel efficiency. The Redline 75w90 is 16 cst, their 75w85 is 11.5 , Amsoil would have been a choice of mine but it is harder to order in my area, the Amsoil fluids are 75w85 is 13 cst, with 75w90 being 16 cst. Amazon ships Redline fluids next day no charge.

 

[zeroptzero]

I was able to get about 1.3 quarts of Redline 75w90 into my differential tonight. I always have issues finding a pump that works well with Redline bottles. The one I use just barely gets the job done, and then I toss it. The Redline 75w90 has a strong smell , I hope that is a sign of a good fluid lol