**Acknowledgment**

The authors would like to acknowledge several very interesting discussions on friction related topics and want to express their gratitude in particular to C. Forstner (MIBA Bearing Group), F. Novotny-Farkas (OMV Refining & Marketing GmbH), A. Skiadas (K & S Gleitlager GmbH) and O. Knaus (AVL List GmbH).

Further, the authors acknowledge the kind permission of the MIBA Bearing Group and the OMV Refining & Marketing GmbH to publish the results and the financial support of the 'COMET K2 - Competence Centers for Excellent Technologies Program' of the Austrian Federal Ministry for Transport, Innovation and Technology (BMVIT), the Austrian Federal Ministry of Economy, Family and Youth (BMWFJ), the Austrian Research Promotion Agency (FFG), the Province of Styria and the Styrian Business Promotion Agency (SFG).
