Kranis

Hi there, wishing you all a Merry Christmas and a blessed new year. I have a W203 C200 Kompressor 2003 model. Three months ago i did a minor service (changed engine oil and oil filter). I used the correct grade of Castrol oil listed on their website. An oil leak has developed from the oil cap. When i remove the oil cap with the engine running, i can see quite a bit of blow by. I am replacing the oil cap regardless but am concerned about the blow by maybe pressurising the the engine and causing the leak. A friend of mine asked a MB mechanic and was told that some hoses at the supercharger can be a problem causing this. The car only has 44,000km. On the hoist we can't see much around the supercharger. Any ideas? Thanks and all the best