Hello municipality. I have a question. At the last oil change I filled Castrol Magnatec 5 W 40 in my 850 2.0 10V. With about 60,- Euro for 6 liters not exactly a bargain. (the friendly wanted but smooth the double)! Now I opened up a raffenery near me, they sell their oil with absolutely identical classification for 23,- Euro per 5 liter. But a friendly mechanic advised me not to use this oil because he also tried a cheap oil once and found a clear flapping of the valves on his car afterwards. Ask now, do you have similar experiences to report? Thanks for the help!!!