The drain plug appears to be steel as is the fill plug. Hopefully it has a magnet as the transmission folks say.

I don't know the correct part numbers for the drain plug or the washers. As a note when removing the fill plug I couldn't see a crush washer on the plug or the trans axle...... When re-reading the Cayman Register procedure they show the drain plug as M22 X 1.5 without a sealing washer. I spoke to my local Porsche parts guy and he said they could see the M22 drain plug mentioned in the trans axle fluid change work instructions. He has sent a message to Porsche about the error in the Spyder PET. The GT4 PET is wrong too.

 

Per my local dealer the correct trans axle drain plug part number is N-100-371-06. I do not believe it is magnetic. The drain and fill plugs share the same part number. I've ordered a magnetic M22 X 1.5 from Dimple.

 

Seeing as you already have OEM plugs, when you swap in the new ones (or if you want to climb under your car early and remove the fill plug again beforehand) can you actually test whether they're magnetic just with a paperclip or something? GTGears has mentioned a few times that at least the drain plug is magnetic, granted not on the GT4 specifically but I would be surprised if the magnetism of the plug were removed specifically for this car, and if it was, I'd want to know why before replacing it with a magnetic version.

 

Just FYI:

Mobilube PTX 75w90

Viscosity @ 40 C 77.6
@100 C 14.5

Shell Spirax S5 ATE 75w90

Viscosity @ 40 C 81
@100 C 14.9

Mobil 1 Delvac 75w90

Viscosity @ 40 C 120
@100 C 15.9

Swepco 201 80w90

Viscosity @ 40 C 140
@100 C 16.2

So the 40 C number tells you how stiff the transmission will be for a cold start (lower better) and the 100 C number tells you something about the performance at the track (higher better). I just included the last one because that's what I have in my Subaru now.

 

the properties and tech data for them are so similar, at least on paper it looks like they would work just fine. Motul 300 would another choice.

 

I got a spare correct drain plug the other day ( P/N N-100-371-06 ). It is steel but is not magnetized.

 

I changed my trans axle and engine oil today at 1960 miles. The stock trans axle drain plug is steel but not magnetic and uses no crush washer.

The car was level on jack stands and when I removed the trans axle fill plug some oil flowed out to my surprise. Upon refilling the trans axle I couldn't get more than 3 liters into it. Spec is 3.2 liters.

I installed Dimple M22 X 1.5 magnetic drain plug and crush washer in the trans axle. Refilled with Mobil PTX 75W90 purchased from Sun Coast. It looks like they are repackaging the PTX 75W90 into one liter containers, works for me.

 

So if there is no crush washer from the factory and the Porsche Bulletin doesn't show one, is everyone adding a crush washer? I checked with Suncoast again and they didn't recommend one.

 

I had mine changed at a local Porsche dealer and when I questioned if there was a crush washer and how tight I was told it's a tapered plug and is not supposed to be torqued much.

 

More confusing trans.fluid info: I had mine in for a 4-3 downshift grind, which was rectified by changing the trans.fluid to: 000-043-305-48P. This seems rather available (as ..-48), is not shown in any of the PET resources available (to me), BUT totally transforms the transmission shift feel. Butter smooth and no more grind.
If anyone has info as to what is actually behind the 000-043-305-48P part number, would be greatly appreciated. Shop indicates that it is GT4 specific.
Either way, after one DE, it's the fluid to use IMO.

 

Even in the middle of Los Angeles summer the , the Swepco creates noticeably stiffer shifts from 1-2 in the morning(ambient 60-80 degrees). It is perfect after 5 minutes of driving.The 'gain' at high temps is small - see specs below. Imho Swepco is O.K. for flushing out old gearbox oil before you use the specified oil. We have had epic Threads trying to find a better substitute and failed.

 

I changed my transmission oil just after break in last year. Used Mobil 1 75w90 from the local auto parts store. After 8 track events, No issues. No crush washer. Knowing that transmission heat is a problem with our cars, I'm considering using Motul Gear 300 for the next change. It has an excellent viscosity index. I know it's not "Approved". I use unapproved Motul 300 V in the engine as I have for several years in my 987 track car.

 

The 991 Cups run really hot. AJR stopped using Delvac in the Weathertech cars last year and went over to the Motul. Brought the gearbox temps down about 25 degree F. But those are sequential dog boxes with no synchros. Please report back on the shift quality in the Cayman.

 

I switched to Motul 300 LS 75w90. It doesn't feel quite as smooth as the factory fill. Two track days and no issues.

 

GTgears: On a new transmission, would you drive some amount of miles and change the gear oil before doing a track day?