BMW SMG transmission 75w140

[bwco]

I know this might not be the best forum to ask which oil to use to fix a differential groaning/chatter issue. I know that I would end up with the OEM BMW fluid. But I had this bugging my brain for the whole day today trying to think about it.

Question: Am I naive to think that royal purple oil is far inferior than BMW OEM fluid that's produced by Castrol ? What I believe in is that R&D of Castrol germany is way more technologically advance than royal purple (or insert any 2nd tier oil here). I mean OEM products usually goes through lots of R&D and spent hundreds of thousands of dollar to develop a product. Compare to say redline, royal purple, or amsoil may not even have the proper equipment to test their products.

 

[Lead Shoes]

I wouldn't say that royal purple is inferior, many people use alternative performance fluids in place of the OEM fluid with excellent results, its really up to you, but I would try different oils until I found what fit my needs the best.

 

[Doug Hillary]

Hi,
bwco - I vcan assure you that the Castrol/BMW gear lubricants are right at the "top of the tree" - great products with an excellent "track" record!

 

[jaj]

Originally Posted By: bwco
I know this might not be the best forum to ask which oil to use to fix a differential groaning/chatter issue. I know that I would end up with the OEM BMW fluid. But I had this bugging my brain for the whole day today trying to think about it.

Question: Am I naive to think that royal purple oil is far inferior than BMW OEM fluid that's produced by Castrol ? What I believe in is that R&D of Castrol germany is way more technologically advance than royal purple (or insert any 2nd tier oil here). I mean OEM products usually goes through lots of R&D and spent hundreds of thousands of dollar to develop a product. Compare to say redline, royal purple, or amsoil may not even have the proper equipment to test their products.



BMW has a friction-modified version of SAF-XJ 75w-140 diff oil that solves the chatter issue. Get it from a dealer or online. If this is for an E46 M3, there's lots of information available on the M3 forums to indicate the part number. It comes in 500ml bottles and I think it takes 4 to change the diff oil on an M3 (this is all from memory).

Royal Purple makes great gear oils, but the Castrol SAF-XJ that BMW recommends is the better product for your needs. There's a tech note at www.diffsonline.com (a specialty BMW race differential shop) that basically says "we've tried them all and the only fluid that never gives us noise or chatter problems is SAF-XJ".

 

[oggb]

+1 for OEM

Sometimes it really is worth it.

 

[bwco]

I am gonna use oem fluid.

But my question is like, does it take a random guy at royal purple to produce a gear oil, but it takesa professional team at castrol, spending hundred and thousands of dollar and R&D to make the BMW oem fluid?

 

[Doug Hillary]

Hi,
bwco - The Technical liaison between the likes of BMW and Castrol is absolute. They (the Oil Co) typically has resident Development Engineers and they work on advanced projects - and build on the experence gleened from end users (Warranty) experience. Component suppliers are usually part of the development process. Extensive Field Tests are typically part of the plan!

And of course the Chemists and Engineers at other Oil Companies do their best at playing "catch up"

In the case of BMW third party "Engineering houses" are used as is the Nurburgring in the Eifel Mtns!

 

[dparm]

Castrol's TAF- and SAF- products are very very good. The only things that comes close, in my opinion, are Motul Gear 300 and Lubro-Moly Vollsynthetisches Getriebeöl.