Differential Gear Oil

[603Racing]

Gasket = black RTV

[Emre]

I use Amsoil "Severe Gear" 75W-140 in the track car.

Pretty much any 75W-90 lube should be OK for a street-driven E30. Most people use Redline. That's what Mike Miller and all the BMW gurus recommend.

[mcr_driver]

how does the 140 compare to the 90? were you running the 90 before and felt it wasn't sufficient? Curious to your concerns and why the higher fluid.

[Emre]

Track cars running race suspensions and wide DOT-R tires put a lot of strain on the LSD, especially when you're sliding around a bit (4-wheel drifting) to help rotate the car through corners.

Personally, I've never had a problem with 75W-90 in my E30. But diff-builders (such as Dan from Diffsonline) recommend going with the heavier-weight lube to reduce wear in dedicated track cars on R-comps. On my previous E30 running a medium-case 4.10:1 LSD diff, I noticed it ran quieter (less bearing noise) with 140 than regular 90. I figure that's got to be a good thing.

[ELVA164]

Red Line 75w90 has the LSD additive already in it.

Whoops, guess I forgot to mention that part.

[mcr_driver]

Track cars running race suspensions and wide DOT-R tires put a lot of strain on the LSD, especially when you're sliding around a bit (4-wheel drifting) to help rotate the car through corners.

Personally, I've never had a problem with 75W-90 in my E30. But diff-builders (such as Dan from Diffsonline) recommend going with the heavier-weight lube to reduce wear in dedicated track cars on R-comps. On my previous E30 running a medium-case 4.10:1 LSD diff, I noticed it ran quieter (less bearing noise) with 140 than regular 90. I figure that's got to be a good thing.

Hmm...I might be willing to give 75w140 a for my next diff, I like a nice quiet smooth running diff that I know can take beyond the abuse I can toss at it on a whim. Where do you get yours from and how much will it set you back if you don't mind divulging?

[dougie30]

I always use lucas lsd stuff

[Emre]

Just order direct from the Amsoil website. I think it's under $20 per liter and you shouldn't need note than 2 liters for a complete flush-and-fill.

[Wanganstyle]

Red Line 75w90 has the LSD additive already in it.

LSD additive makes the internal discs slippery; this is BAD for track lap time but good for quieting a street car.

The garbagejunkyard diffs in 90% of r3v cars need all the grip possible to hold.


I like 75-90 Lubo Moly Gear oil; It is the proper range and very low drag.

High performance racing differentials (not stock 30 year old oem units) often use a very high range fluid;

Os giken specifies a 80-250W fluid for the Super-LOK units; using a LSD additive will ruin them.

[Smelser]

Welded open diff. for the race track.
running half oa can of STP (the old mollassas stuff)
the rest is 80w90

if its open, just use any gear oil that is cheap. DO NOT DO THIS IF IT IS A LSD. thats when you spend the money on synthetic.

[cyrmanj]

I always use lucas lsd stuff

^ Did you use Lucas 75W140? I am asking because Lucas Oil is just starting to import to my country (Costa Rica) and they are pricing agressively, is it a good oil for E30s LSDs? In my country since this oil brand is new we do not know anything about it.

Anyone uses Castrol Syntrax for your LSD's?

My E30 has a 3.73 LSD and I've always used Redline 75W90, however I see a discrepancy on recommendations, since the "proper" weight for a LSD seems to be 75W140, or is it?

Today I noticed a possible leak on the diff so since I have to replace the diff bushing I also want to check for the source of the leak and replace the oil as well.

[Wanganstyle]

If the fancy name brand oil going into the differential is worth more than the old mystery diff......stop right there.

Differentials are wear items; the bearings often go before the seals- my dd e34 525 had 299k when the pinion bearings died; seals were all still ok.

Lsd additive DECREASES lockup. It the majority of r3v cars with old used stock units this is detrimental to sporting performance.

Your old e30 diff+ the cheapest generic dino oil from wal mart without lsd additive= faster lap time than using redline lsd oil or swepco/amsoil lsd specific oil.

Lsd additive reduces grip of the differential internals for parking lot/oem use in a new 0 mile bmw with a 0 mile oem lsd. Who has one of these now????

The diff does not care if its synthetic or dino oil; 98% of r3v cars don't have the performance level built to take advantage of the diff potential; and cant handle the stress of a built differential either.

Bmw oem differentials are happy with 75-90 gear oil; the only time its temp range can get out of that zone is if the unit is built high locking with different internal confirmations that increase the temp.

The only times something other than 75-90 is needed:

A: Built high lock diff+endurance racing.
B: OS-GIKEN differential (special formula uses 80-250w oil exclusively and a 80-140w option for sprint racing)


75-140w won't hurt anything but the thicker oil will have more rotational drag.


As far as my qualifications for differential specification:

I produce my own original billet cnc LSD; endurance race a 24v e30 myself and build professional differentials for Os Giken sponsored racers & track record holders

Sent from my GT-N7100 using Tapatalk 2

[FLG]

If the fancy name brand oil going into the differential is worth more than the old mystery diff......stop right there.

Differentials are wear items; the bearings often go before the seals- my dd e34 525 had 299k when the pinion bearings died; seals were all still ok.

Lsd additive DECREASES lockup. It the majority of r3v cars with old used stock units this is detrimental to sporting performance.

Your old e30 diff+ the cheapest generic dino oil from wal mart without lsd additive= faster lap time than using redline lsd oil or swepco/amsoil lsd specific oil.

Lsd additive reduces grip of the differential internals for parking lot/oem use in a new 0 mile bmw with a 0 mile oem lsd. Who has one of these now????

The diff does not care if its synthetic or dino oil; 98% of r3v cars don't have the performance level built to take advantage of the diff potential; and cant handle the stress of a built differential either.

Bmw oem differentials are happy with 75-90 gear oil; the only time its temp range can get out of that zone is if the unit is built high locking with different internal confirmations that increase the temp.

The only times something other than 75-90 is needed:

A: Built high lock diff+endurance racing.
B: OS-GIKEN differential (special formula uses 80-250w oil exclusively and a 80-140w option for sprint racing)


75-140w won't hurt anything but the thicker oil will have more rotational drag.


As far as my qualifications for differential specification:

I produce my own original billet cnc LSD; endurance race a 24v e30 myself and build professional differentials for Os Giken sponsored racers & track record holders

Sent from my GT-N7100 using Tapatalk 2

He also builds em for saps like me who want a proper lsd on their drift car. Hands down one of the best upgrades I did. And no need to hop around on a welded diff.

Also i use 75-140 Redline ns fluid (non slip, no additive)

Sent from my SCH-I545 using Tapatalk 2

[SpecM]

Is GL-5 ok for diffs?

I know we shouldn't use it in g260s

[Bmr]

Use use Castrol syntrax 75w-90 in my 4.44. I really haven't noticed a difference between that and Redline. Limited slip gear oil is GL-5