Last weekend I finally decided to rotate my tires after 26k miles, since front started showing wear on the edges. Since I had to take all the tires off, I decided to wash the rims as well. To my surprise I found few millimeters of grease spread on the inside of front left rim. The grease was covering half of the diameter of the rim and it looked like wheel bearing grease leaked out when the car was parked (seemed like grease was only on the lower part of the rim, rotating tire would spread the grease all around.) I never took the tires off before so it could have been there all the way from factory, or maybe it got there when my dealer was changing oil one time, but it makes me wonder if it's not something coming out of the car. It's a heavy grease, not oil, so it could be coming from steering box, wheel bearing or one of the shafts or bushings, but I can't find anything unusual or any grease anywhere else. Seems like the grease was old, covered with a lot of dirt. On the other hand after washing the grease and dirt, it's the cleanest, most shiny rim inside of them all. Others have chips and spots that can't be cleaned, that one is perfect, so I may put some thin layer of grease for protection.