Something does not pass the 'Common Sense and Good Judgment' check. What am I missing

[BTM]

Originally Posted by cliffhopper

Not to derail the thread, but what would happen if you use a thinner oil like 75-90 in the diff?

SAF XO is 75W90, which is the open diff spec for BMWs. My understanding is it won't sufficiently lubricate the clutches in the M diff, it isn't "sticky" enough, and cause excessive wear and premature failure. For a visual, compare a clutch type LSD (this one is an OS Giken on Turner's website) to an open diff

[gcochard]

I have a suspicion that my indy shop put redline 75W90 in my diff (thats what it says on the invoice). I will be taking it to another shop and having them check/replace it for me.

Then I'll have blackstone analyze it.

[XMetal]

Originally Posted by cliffhopper

I have a suspicion that my indy shop put redline 75W90 in my diff (thats what it says on the invoice). I will be taking it to another shop and having them check/replace it for me.

Then I'll have blackstone analyze it.

Just curious, which Indy do you use since I'm always in the look out for a good one. Thanks.

[wassup61]

The 90 vs 140 at op temp viscosity ratingis for sufficient lubrication at those high slip temperatures. With a 90 weight, the clutch packs are subject to more wear sooner due to insufficient slip in the plates.

[gcochard]

Originally Posted by XMetal

Just curious, which Indy do you use since I'm always in the look out for a good one. Thanks.

First I tried Bullet Performance in Costa Mesa. I'm gonna try Solely Bimmer in Mission Viejo as they come recommended from Dr Vanos (at least for vanos installs).

[Hairballs58]

Soley Bimmer is where I take my car. So far, I cant recommend them highly enough.

[bluecobra]

My indy shop put Redline in the diff of my E46 M3 and I started noticing noises on tight, slow turns - parking lot manuvers and speeds. I changed it back to the OEM stuff and it never made a noise again.

I will stick to the OEM fluid for the diff in my Z4 M.

[mfanatic325]

Originally Posted by bluecobra

My indy shop put Redline in the diff of my E46 M3 and I started noticing noises on tight, slow turns - parking lot manuvers and speeds. I changed it back to the OEM stuff and it never made a noise again.

I will stick to the OEM fluid for the diff in my Z4 M.

Precisely what my indy shop warned me about
Hence why I'll put in the SAF-XJ stuff only, for the diff.

[tekmoe]

Originally Posted by bluecobra

My indy shop put Redline in the diff of my E46 M3 and I started noticing noises on tight, slow turns - parking lot manuvers and speeds. I changed it back to the OEM stuff and it never made a noise again.

I will stick to the OEM fluid for the diff in my Z4 M.

Bummer, I've been running Redline 75w140 in my diff for almost a year now with almost 10k miles on it and I haven't heard a peep out of it. Tight turns, slow turns, different speeds - no sounds at all. Redline has never let me down.

*edit* Also, how do you know your shop used the correct fluid? And the correct amount of fluid? Were you standing there watching them do it? If not, it's anybodys guess. I did this myself so I KNOW it was done right. And again, I've not had a single issue.

[bluecobra]

Originally Posted by tekmoe

Bummer, I've been running Redline 75w140 in my diff for almost a year now with almost 10k miles on it and I haven't heard a peep out of it. Tight turns, slow turns, different speeds - no sounds at all. Redline has never let me down.

*edit* Also, how do you know your shop used the correct fluid? And the correct amount of fluid? Were you standing there watching them do it? If not, it's anybodys guess. I did this myself so I KNOW it was done right. And again, I've not had a single issue.

Well, if you really need to know, yes I was there.....also he is a personal friend of mine and used the Redline because he had always used it on E36 M3s. He did not think it would hurt anything, and it may not have. However, I did not like the noises. I changed it to the OEM fluid myself and it immediately stopped the noises.

Was the Redline the cause of the noises? Never made them before and never made them after....Who knows, just sharing an experience, Do whatever makes you happy.

[tekmoe]

Too bad for you. Hope your diff is ok...

[imom]

mfanatic and bluecobra so did you change the diff oil SAF-XJ with the friction modifiers or without? I'm about to do a full oil change from front to back at 32K miles. I don't know what the stock Z4M have... regular SAF-XJ and only apply the FM version for the slow turns or it comes stock with FM version already. I don't want to swap out the diff oil twice. Thanks

[imom]

Bump for mfanatic and bluecobra to respond...I'll send a PM as well.

[mfanatic325]

My shop said to use the version with friction modifier, so I did. It's been approximately 10k miles now since I got my diff rebuilt with the 3.91 ring & pinion, and I've yet to swap the diff fluid out a third time. Will be doing the flush in two or three week's time.

I don't have any noises coming from my diff. Not sure if the REM-polishing on my ring & pinion helps with that. I've heard that the polish reduces friction and ultimately heat. Perhaps my fluid will be in decent condition because of this

[bluecobra]

Originally Posted by imom

Bump for mfanatic and bluecobra to respond...I'll send a PM as well.

I used the stuff with the friction modifier. Sorry for the delay, I wasn't watching the thread.

[imom]

thank you both for the reply