Vilhuer

Porsche specs call for SAE 90 API GL-5 oil for automatic PSD diff. 3L for S4 and 1.9L for GTS. There is a lot of talk about using Redline 75W90 and 75W90NS oil mixed together in 5sp LSD boxes but I could not find much info from archives on what to use in automatic PSD diff. No slip version is for syncro rings and probably isn't good idea in automatic diff. Is normal 75W90 best option or should I use for example Mobil 75W90 SHC-LS which is specifically meant for limited slip diffs?

paalw

Hi Erkka,

did you ever find any info on this subject? What did you end up with? I am planning the same job.

Vilhuer

Late reply as I have had very little time to hang around here lately.

Since 2010 I have had some hands on experience of Redline in GT manual gearbox. Due to it Redline is no longer option on anything. On my ex automatic GTS I used normal Mobil without any LS stuff in it.

polecat702

I went with Mobile 1, 75/90 LS in my 89, when I changed transmissions. My car has limited slip differential. Mobile 1 ATF for the automatic.

If I recall correctly, Greg Brown recommends using Mobile 1 because everything else causes leaks. Greg's advice is the gospel as far as I'm concerned.

Ducman82

do the mobile LS... can't go wrong