Feedback about Redline 75w140 for the differential

[drwankel]

I'm curious if anybody has been running Redline 75w140 in their rear diff, and what your experience has been.

I've used Redline gear oil in many cars before this (not BMWs), and found it to be an absolutely fantastic gear oil for a differential. Just curious if there is any reason why I shouldn't run it on the M.

[dparm]

Originally Posted by drwankel

I'm curious if anybody has been running Redline 75w140 in their rear diff, and what your experience has been.

I've used Redline gear oil in many cars before this (not BMWs), and found it to be an absolutely fantastic gear oil for a differential. Just curious if there is any reason why I shouldn't run it on the M.

I doubt you'll notice much difference. It contains FM but probably less than the "heavily-dosed" BMW fluid, so you might notice slightly better locking....might.

The only other real difference versus the OEM Castrol Syntrax LS is that Red Line has a VI that's about 10% higher and it's about 10% thicker at high temps, but again, you won't really notice that. The Brookfield viscosity is also higher, so some would argue that it'll have "worse" cold weather characteristics.

[GMWNashville]

It makes the diff chatter...so I personally don't use it in m cars that require fm

[dparm]

Originally Posted by GMWNashville

It makes the diff chatter...so I personally don't use it in m cars that require fm

The Red Line fluid contains FM. If you have chattering issues, add more. It's personal preference.

[GMWNashville]

I realize it has some..the noise gets annoying in a street car.

[Doc Oc]

I've been running it for 12,000 miles. No complaints. When I first switched there was a little bit of diff noise on slow right turns so I bought a bottle of friction modifier and added just a little at a time. Took about 1 oz to get the noise gone completely. Been perfect since then.

[buddalun]

Originally Posted by GMWNashville

I realize it has some..the noise gets annoying in a street car.

Originally Posted by Doc Oc

I've been running it for 12,000 miles. No complaints. When I first switched there was a little bit of diff noise on slow right turns so I bought a bottle of friction modifier and added just a little at a time. Took about 1 oz to get the noise gone completely. Been perfect since then.

Thanks gentlemen.

I too am considering switching to RL from OE fluid. It's interesting that the RL diff fluid (even with FM) still causes chatter on our diffs. Is this of concern? Is OE fluid ideal here? TIA

This the specific fluid I am looking at:
http://www.redlineoil.com/product.aspx?pid=134&pcid=4

[Doc Oc]

I don't think it's of concern at all...I'm sure the red line, because of its racing heritage, uses less modifier than the oem fluid. For all we know, even with an oz added, there may still be less FM in the diff than with OEM. Red line makes great gear oils, I wouldn't worry about it.

[elim11]

I have it on my car currently for the past ~3,000 miles and 3-4 track days. So far so good. No issues, nor abnormal noises. Performance wise, I don't notice a DIFFerence. hehe see what i did there.

[dparm]

Originally Posted by buddalun

Thanks gentleman.

I too am considering switching to RL from OE fluid. It's interesting that the RL diff fluid (even with FM) still causes chatter on our diffs. Is this of concern? Is OE fluid ideal here? TIA

This the specific fluid I am looking at:
http://www.redlineoil.com/product.aspx?pid=134&pcid=4

Friction modifier is added to "personal taste". The only reason the OEM stuff has so much is that 2008 MY owners complained about chatter. My advice is to start with a fluid containing a normal amount of FM. If the noise bothers you, add more until it goes away.

I will be honest: my car had the OEM high-FM stuff in it for the first 2 1/2 years and 20k of the time I've owned it. I had the normal-FM stuff (Castrol Syntrax LS) put in earlier this year and I can't tell the difference. I'm not deaf, but I am definitely not going to brag about above-average hearing. It's not like I drive around focusing 100% of my attention on very minor noises like that. I've usually got the radio on or there's tons of background noise from tires, other cars, exhaust, etc.


Remember, more FM changes the LSD locking behavior. I asked this exact question earlier this year before settling on the Castrol factory-fill fluid:
http://www.bobistheoilguy.com/forums..._for/against_F

Take special note of MolaKule's reply. He is a tribologist, meaning oil chemist/blender. He knows his stuff:

LSD "modifies" the friction coefficient to reduce chatter.

I always recommend adding about 1 ounce increments of LSD additive at a time and then doing figure 8's in a parking lot with a warm diffy.

If it still chatters, add another ounce.

Most people DO add too much of the additive such that the LS may not lock up when needed.



And yes, that Red Line fluid you linked is the correct stuff. My only concern with it versus OEM or the Castrol FF is that it's about 20% thicker at higher temperatures. It does have a very high VI of 198, which is a good thing.

If you are looking for OEM alternatives, we can absolutely discuss that! Torco SGO, Renewable Lube, Gulf Competition, Millers, etc.

[nholmes]

I run this in my car because I had some left over from my upgraded evo diff.

To me, there is no perceptible difference between the OEM fluid and the RL stuff.

YMMV

[buddalun]

I am going to have the RL diff fluid put in tomorrow morning. I will report back with my results.

Thanks everyone!

[RoundelObsession]

I use Redline in the differential and transmission with great results. Make sure you get the diff. fluid with the fm, they sell it with and without fm.

[buddalun]

Originally Posted by RoundelObsession

I use Redline in the differential and transmission with great results. Make sure you get the diff. fluid with the fm, they sell it with and without fm.

Yes, that is this product here (with FM):
http://www.redlineoil.com/product.aspx?pid=134&pcid=4

That is what I'm using. To be done tomorrow morning. I'll drive this weekend and report back.

[Doc Oc]

Pay close attention to right hand turns when the diff is cold....that's where the noise is most obvious. I'd go ahead and order a bottle of FM if I were you

[buddalun]

Got the car back this evening. Took a long drive home on the freeway, took some tight twisties on backroads, and did regular slow-paced city driving. I hear no difference from the diff, nor do I feel any difference. Seems like the RL is a great alternative to the overly spendy OE fluid.

[Doc Oc]

Yup it seems like good stuff. The only time I noticed a noise was on slow tight rights when the diff was cold.

[drwankel]

Really appreciate the feedback, guys.

[oolas3]

Originally Posted by dparm

If you are looking for OEM alternatives, we can absolutely discuss that! Torco SGO, Renewable Lube, Gulf Competition, Millers, etc.

Any opinion on Mobil 1 gear oil for the diff? It's an absolute bargain but you may get what you pay for. I'm currently happily using the Castrol but was just curious.

[dparm]

Originally Posted by m3m3mr

Any opinion on Mobil 1 gear oil for the diff? It's an absolute bargain but you may get what you pay for. I'm currently happily using the Castrol but was just curious.

I'm sure it will work fine.

The only reason the OEM stuff costs so much is because Castrol doesn't sell Syntrax LS on retail shelves here. In Europe, that fluid is easy to get and inexpensive. I don't think it's any better or worse than the Mobil fluid.

[drwankel]

So I went ahead and putt in the redline fluid yesterday.

I've always thought that my m3 LSD was obnoxiously loud.

The redline fluid has dramatically quieted down the diff. I don't know what the heck was in it before, if it was from the factory, or some dealer put something in, but it seemed too loud to be normal.

I'm almost suspecting that the previous fluid was not the correct fluid. No other m3 I have driven was that loud.

Anyway I solidly recommend the redline fluid. Its good stuff.

[Hujan]

I am curious how you gents are pouring the Redline in the diff. The OEM stuff comes in a bottle that allows you to "inject" it into the pumpkin if that makes sense. But the Redline bottle is difficult to fit up in there. I had to use a Mity-Vac to get it in there. Any trick I am missing?

Also, are you guys replacing the fill/drain plugs? I think they are single use.