All the fluids changed for limited use and storage here in winter. Castrol Syntrax 75W90 for the gear and rear axle and Shell Helix synthetic 10W40 for the engine.
It's only about 1500 km since the dealer supposedly did a minor service, including filters and fluids. However, since I found several screws and other bits and pieces missing or misapplied and the flilling plugs on the gear and rear drive needed a breakerbar to unscrew, one has to question the competence of the 500 lb. gorilla that did the service.
The question of oil recommendation: The standard 20W50 oil recomendation is apparently only available today as a "motorcycle" oil, where the friction modifiers have been omitted for use in bikes with wet plate clutches. Since the K has a dry clutch, my thought was that a modern automotive synthetic including the friction modifier additives would be preferable. It does not aseem to exist in that viscosity range. My favorite supplier, the local Sunico distributor has two candidates: 5W50 or 10W60 - both up to the latest API specs SH/CD for use in both petroland diesel engines and meeting a lot of various marque specifications like VW, Porsche etc.
There has been quite a discussion on this subject in Germany, where there seem to be a vocal preference in some circles for using standard 10W40 oil year round. I do not feel there is any difficulty with using the 10W40 here in witer - temps not over 12°C or 55°F. Summer temps here are rarely over 25°C and never more than 30.
So, what's the opinions here?