What oil for my 2002 2.7 gearbox/diff
 

As above what oil should i put in the diff/box of my 2002 2.7 manual, its a uk car if that matters?

I have looked on here and on the net but there is a lot of conflicting information.

Thanks.

You're not kidding!
I just went with the factory fill gear oil from the dealer. A bit pricey, but no cold shift issues at all.

The five speed cars used an odd product that is different from the six speed cars. As mentioned, you won't go wrong with the factory product.

+1

I run a slightly heavier gear oil designed for motorsport and it is great once the car is fully warm. On a cold morning, no shifting will happen until you get some heat in the motor and trans.

I maybe sending you on a wild goose chase because I'm not sure what is available in the UK. That said I use Valvoline Syn Power Full Synthetic 75W 90, Hypoid recommendation meet recommendations for API GL-4 and GL-5, MT-1

Is this the right fluid for 5 or 6 speed?

http://www.ecstuning.com/Porsche-2000-Boxster-986-Roadster-Convertible-H6_2.7L/Drivetrain/Differential/ES1513799/

In the service manuals I saw that some of the old fluids were specified only for 5 or 6 speed but I thought that the above was for both, part number 99991754600.

Hard to tell, that looks like a repack of some kind. Here is the official list for 5 and 6 speeds: http://www.renntech.org/forums/index.php?app=core&module=attach&section=attach&at tach_id=30748

Interesting question in view of the bearing and 2nd gear issues with the 6 speed manual gearbox. The bearings that fail are sealed ,so the transaxle oil choice should be irrelevant- unless one oil provides better cooling than another ? The 2nd gear teeth are just too small -so oil spec won't help?
Here is an interesting discussion of GL4 vs GL5
GL5 gear oil bad in tranny,fact or myth? | ATF, Differential, Trans, Brakes, P/S | Bob Is The Oil Guy

Factory fill. Works fine even in my Boxster race car.

Just so you know, GL-5 is suitable in differentials so ancient that they called for GL-4.

It is, however, NOT suitable in transmissions where GL-4 is specified.

The best fluid is Porsche... I have tried others and had issues shifting when cold. You should be able to purchase from Suncoast:

Manual Transmission Fluid - 75W - 90:Porsche Parts & Porsche Accessories - Wholesale Porsche Parts & Tequipment

That Porsche bulletin says 999 917 546 00 is OK for manual trannys and diffs for Tiptronics. It only states that the Burmah stuff isn't to be used in the "S" 6 speed trannys.

IIUC 999 917 546 00 is a special blend Shell makes up that's partway between the US GL-4 and GL-5 specifications. More EP additives than GL-4 but not as many as baseline GL-5. If you put straight GL-4 in it won't protect the hypoid diff gears: if you put in GL-5 it will over-slick the synchros making for hard shifts.