[roadracer311]

I changed the tranny oil on my 2003 Boxster S when it hit 20k miles in October of 2007.

I work on motorcycles for a living and often get to see what break-in oil looks like coming out of a bike. (it has sort of a pearly look to it from all the tiny metal bits). So, I thought it would be good to get the original stuff out of there in spite of the 90k mile service interval, just to clear out any of the metal that comes off as the gears sort of wear-in to each other.

I did a ton of research and ended up using Redline 75W90 NS. The shifting feels the same as before. Possibly a tiny bit better, but definitely not worse. (Having raced motorcycles for 5.5 years, I'm fairly sensitive to small changes in the vehicles I drive/ride. )

Before and after the oil change, the best thing I've found to keep it from crunching into 2nd gear is to make the 1st to 2nd shifts at 3k rpm until it's warmed up.