Hello All, while travelling to genting yesterday, my E39 525i unable to downshift to lower gear while going uphill. even manually downshift it is not changing to lower gear. after that the engine start to jerk and very small amount of smoke came out under the hood. OBD straight away beep and 'check engine oil level' is displayed and oil icon on dashboard lighted up. a quick check at the engine oil level and it turns out it is at a sufficient level. a mechanic that passed by informed that the smoke is caused by the engine oil leaking to the exhaust and the car should be able to drive on a straight road without issue. so i made an uturn back from genting and true enough on a flat road i am able to drive fine without issue. while driving back, whenever i am going up or downhill the engine will start to jerk slightly and i have to let go of the acceleration pedal to stop the jerking. the car seems to drive fine only on an absolutely flat road. sifus, may you let me know what is the cause for this issue?