Royal Purple Gear Oil 75-140 (with Friction Modifier)

[OneM]

My initial diff oil change was done with Castrol SAF-XJ (without Friction Modifier), and now the car makes some grinding noises during low speed turns. So I'm considering getting an oil with "Friction Modifier'. So far I can't seem to locate any shops with Castrol SAF-XJ + FM so I'm thinking of getting the Royal Purple + FM.

Anyone tried this on their 1M? Any good ..grinding noise?

[CarJunkie]

Why not go to the dealer and get the right fluid from BMW?

From what I have read, the friction modifier takes the noise away, but does not benefit the diff in any other way. Without the FM, there will be audible sounds from the diff that may be disturbing to some drivers, but are not a sign of malfunction.

FWIW, I used RP 75w140 with FM in the rear diff of my RX-8 (torsen-type LSD) and it solved a lowspeed shudder that occured when turning at full luck in reverse (ie backing out of a parking spot). That had developed with the original factory fluid. I can't say whether it was the RP fluid or just changing out the break-in fluid that made the difference.

[Dackelone]

Originally Posted by CarJunkie

Why not go to the dealer and get the right fluid from BMW?

^+1. That is what I would do too.


You will need three 0.5L bottles. The diff holds 1.2L of fluid.

Castrol SAF-XJ with FM...

BMW p/n 83 22 2 282 583


CORRECT 1M Fluids List [Engine, Transmission, Differential]
http://www.1addicts.com/forums/showthread.php?t=620282

[crystaweizen]

Originally Posted by CarJunkie

Why not go to the dealer and get the right fluid from BMW?

From what I have read, the friction modifier takes the noise away, but does not benefit the diff in any other way. Without the FM, there will be audible sounds from the diff that may be disturbing to some drivers, but are not a sign of malfunction.

FWIW, I used RP 75w140 with FM in the rear diff of my RX-8 (torsen-type LSD) and it solved a lowspeed shudder that occured when turning at full luck in reverse (ie backing out of a parking spot). That had developed with the original factory fluid. I can't say whether it was the RP fluid or just changing out the break-in fluid that made the difference.

yea definitely want to run something with a friction modifier on vehicles with LSD. royal purple will work but like he said cant go wrong with the factory fluid. now going against what I said, what can I run as far as aftermarket fluid for a 135i with no LSD??

[Dackelone]

^^You can run the same stuff in a 135i. The Castrol SAF-XJ+FM is also safe to use in regular non LSD bmw trannies.

[OneM]

Thanks for the help guys.

Reason for not buying the BMW oil is the cost. It's like 90 bucks per half litre. BTW I'm already using Castrol SAF-XJ (w/o FM) in my diff, ..can I just buy the 'friction modifier' additive and put it in or do I have to replace the entire fluid too?

[ozinaldo]

Originally Posted by OneM

Thanks for the help guys.

Reason for not buying the BMW oil is the cost. It's like 90 bucks per half litre. BTW I'm already using Castrol SAF-XJ (w/o FM) in my diff, ..can I just buy the 'friction modifier' additive and put it in or do I have to replace the entire fluid too?

I don't think that's the part of a car you would look for creative ways to save a few bucks...but of course that's your car. I myself would never try to save from fluids or tyres and would use just the best. My 2c.