Very timely post- I just did both my '06 GT and '07 GS yesterday and pulled samples for Blackstone on both. I'll post my findings here.
Based on how much I ride, I've always changed the lube on my K100RT at the beginning of every season. So, it is very natural to adopt this for my newer bikes to. my fidings yesterday:
1. I don't care that I don't have a bottom drain plug on my '06. Not having one would tempt me to not look at the splines. After having done my own splines on both '07 GS and '06 GT, it is amazing how dry they get after one year, approximately 10,000 miles. Having to split the rear drive from the shaft to drain it let's me kill two services at one time.
2. The GT had 6,481 miles on the rear drive BMW 75w90. It was VERY ugly and Blackstone is gonna laugh. The GS had 9,105 miles on the rear drive BMW 75w90. It looked brand new. (What's that about?)
3. Using the RepROM, it was intersting to me that the bolt/washer setup for disassembling the paralever in the back was different:
GT: Bolt/washer/lever/no washer/nut
GS: Bolt/no washer/lever/washer/nut
4. All torques were the same, which was expected and convenient.
5. The GT was kind of a pain, the GS was a breeze. The GT's drive doesn't fall completely vertical to the 3 o'clock drain plug. The GS rear drive does. This is NOT a matter of higher ground clearance of the GS- therre is a physical top on the GT that prevents total vertical draining.
6. Before operations yesterday, I got on here and searched around for whether the new thinking is for 75w140 vs the RepROM stated 75w90 oil for both the GS and GT. I didn't find much discussion on the subject so I defaulted to the stated 75w90, which is what I had on hand anyway. I'm going to start a new thread on that for matter of record.
7. I took pics of the splines on both bikes for future records- they both looked perfect. I wish I had taken them with grease and at first exposure after the season so people can see how I goop them up and how dry they look after 10,000 miles. I used Honda Moly 60 as that also was what I had on hand. If anyone has other alternatives, please let me know.
Here's hoping that the GT rear drive will survive the Blackstone analysis.