The only Porsche part in the oil used was the label on the jug.

That is true i'm sure. Never the less my car shifts much smoother now :cheers:

The German liqui-Moly mentioned in one of the links is available here:
http://www.amazon.com/gp/product/B0055HS24O/ref=pd_lpo_sbs_dp_ss_2/181-1076624-8818662?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=lpo-top-stripe-1&pf_rd_r=1XGGXVQMDEHFFMEYR1G6&pf_rd_t=201&pf_rd_p =1944687702&pf_rd_i=B004GWUPOE
if you are stumbling through recommendations for 6+speed lubricants the gearbox part number is Getrag G86/20
The lube spec is: 2.7Lof oil to API classification GL5 75/90
And it has no factory LSD
PORSCHE 986 BOXSTER TRANSAXLE SPECIFICATIONS – California Motorsports Inc
http://pedrosboard.com/read.php?7,27236,27236
After all the reading,my conclusion is the Shell Spirax/Porsche original fill is the beat choice. It is what JFP recommends.
So the remaining question is where to get the ShellSpirax/Porsche oil for the best price. Well the shipping is a huge part of the deal .So I'll try to find a local dealer.

Hi Gelbster,

Shell Spirax S5 75W-90 is in general available in 20 litre and 209 litre barrels. I haven't found anybody that sells 1 Litre bottles over here in germany, or europe.

So we did a group buy in the german Porsche forum. If you're interested in importing 3 litres from germany i can give you a contact adress from a german forum member.

I think the most inexpensive way will be a group buy in the US. I saw that 20 litre cans are offered in the US.

Difference in formula: Well i don't know what additives they use. Also it is very interesting that the oil fulfils API GL4, GL5 and M1, because these API standards are different concerning the percentage of additives. And yes, you're right the oil has a homolgaton for Getrag transaxle transmission. So it should also work for the 5 speed.

Found this transmission oil chart from Porsche for the 2.7 and 3.2 engine. They also recommend Mobil MOBILUBE PTX 75W-90 and a Burnah oil for the 5 speed.

http://986forum.com/forums/uploads01...1424864312.jpg

Have not cheched if there are different versions of the Mobil are available like Shell Spirax. But the Mobil seems to be available in 1 litre bottles.

All other oils don't have a Porsche approval for these transmissions. If you try one, make shure it's a transaxle oil.

I recommend the Shell Spirax S5, because this is the Porsche OEM oil they fill in your transmission when they do a mt tranny oil change.

Regards from germany
Markus

Great info Markus, thank you.
I had found mention of the Mobil Ptx 75-90 and searched to find 3 liters required for a fill. No luck.

* Can anyone find Mobilube PTX 75w -90 in reasonable qty/price?
Or the Shell Spirax S5 ATE 75w-90 .
I tried hard but failed. It would be very helpful info to share with other Forum members.
Thanks for helping us Markus.
Not wanting to confuse but Shell seem to suggest that their newest product -Spirax S6 AXME may be suitable. It is rated for many cars,trucks and heavy equipment so may be more widely available.
The specs say it is GL5(but not GL4) & MT 1. Our spec is shared only with Ferrari !
http://s06.static-shell.com/content/dam/shell/static/usa/downloads/lubricants/cs5867-10-pri-spiraxindirectproductfambroc.pdf

Hi Gelbster,

please compare the oil specifications:

Shell Spirax S5 ATE 75W-90
http://www.epc.shell.com/Docs/GPCDOC_GTDS_Shell_Spirax_S5_ATE_75W-90_%28en%29_TDS.pdf

Shell Spirax S6 AXME 75W-90
http://www.epc.shell.com/docs/GPCDOC_Local_TDS_United_Kingdom_Shell_Spirax_S6_AX ME_75W-90_%28en-GB%29_TDS.pdf

Please compare the kinematic viscosity of the two oils. It's very different. That's why S6 AXME won't work for the Porsche 986 Getrag transmission.

I'll recommend Shell Spirax S5 75W-90.

Best would be a group buy, but you'll need 6-7 people who are interested.

Regards from germany
Markus

Markus, you are correct !
The 40 degree kinematic is way,way different ! 115 vs 81. Too much?
The 100 degree kinematic viscosity is O.K.?
Excellent data resource you found.

Hi Gelbster,

whoa. Dynamic viscosity is really hard to explain for me, because english is not my mother tongue and this is a complex physics topic.

The wrong viscosity can harm much more than using the wrong oil. Cinematic viscosity decribes the viscosity to density ratio. It is measured in mm²/s. You use a Viskosimeter (don't know the english term) to measure it.

Please check Viscosity - Wikipedia, the free encyclopedia for a detailled desription. Think that can explain it better than i can do.

And yes, the difference between 81 vs. 115 is a lot. I think that can cause not only a bad shifting but also damage to the transmission.

Also dynamic viscosity is very different. 35.000 vs. 135.000. That means S6 AXME is 4 times viscous / thicker than S5 ATE. And that will harm the transmission definitively.

So Shell Spirax S5 ATE 75W-90 or Mobil MOBILUBE PTX 75W-90 are the right oils. ;)

Regards from germany
Markus

Parked the car in the garage for now and scheduled to have the Motul oil replaced with OEM oil coming Wednesday. Will update about any difference, I notice.

Shop used the recommended Burmah oil. Unfortunately, I don't think it has made any difference. On cold mornings, 2nd gear still won't engage :( I guess my mechanic was right all along, 2nd gear synchro going bad.

Might look for a used tranny in an year or two!

I had the same problem. Read somewhere a guy explaining how he nudged the shifter downward into what you can feel is a small gap just before going through the process of shifting into second Works for me

Try getting the cables adjusted. If you can remove the consol yourself then you save a few hours labor.

Thanks, will have cables checked but also had a short shifter installed so I guess they straightened out the cables when installing the shifter?

Mine shifts better from cold (read below zero) if after starting and while putting on my seat belt, I let the car idle in neutral with clutch out.

Oil
 

You are supposed to fill the transmission with the case at full operating temp. If you fill it cold you are over filling it. Is it possible you have over filled the case??

I am gonna have to call BS on this theory.

The reason that a transmission would be easier to shift after it warms up is that the viscosity of the oil improves, gets runnier with heat. This lets the synchros hunt as they should, instead of spin around, stuck to the assembly

The metal parts do not shrink or expand in such a way that they bind and cause things to be harder to shift. Porsche tolerances are tight, but not THAT tight!;)

Yes, having badly worn synchronizer rings is not going to help either.

Erik is correct in terms of the long term prognosis and it is the accepted conventional wisdom of the Forum. But perhaps they are all babbling fools?
Erik's polymer chemistry may be a bit shaky but he is helpful gearbox mechanic not a chemist !.
What he mean't(I think) to say is perhaps the friction modifiers in the unique additive pack for this "Porsche- spec " Spirax may have a critical function.That additive pack is unique to this spec of Spirax.
The ultimate authority (certainly not me!) on this issue is probably GBox or Forum Members GTgears and JFP. They have previously contributed to discussions on this subject very clearly and in detail.
I mention this so people reading this subject for the first time Search on the 6 speed lubrication subject before they damage their gearbox by using the wrong oil and thinking they dodged the Porsche tax.They might. But they'll get fined for tax evasion!
That said, neglecting the routine gearbox lube change could eventually cause more damage than using a generic oil ?
Without a CMS Shift Arrestor some say any 6 Speed is doomed so perhaps the whole discussion is moot ?