He said that another Boxster owner was reporting cold condition hard shifting and he used the OEM transaxle oil to correct the symptoms. I was experiencing that same symptom for the 2 to 3 shift when the transmission was cold.
I bought the OEM oil from Sunset about a month ago. PN 000-043-305-49 (~$28/liter). I bought 3 liters and the mechanic installed all of that to fill it, with very little to spare. Mine is an '00 S six speed. He removed the diagonal brace to access the drain and fill holes. I read that compromising the diagonal with an access hole could weaken it and impact handling.
The plastic bottles looked like this one:
https://www.getporscheparts.com/oem-parts/porsche-transaxle-oil-75w-90-1-l-00004330549
After a month of weekend driving, the symptoms have gone away.
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