I was looking for advice concerning the compatibility of computer science with mechanical engineering. I have had an interest in mechanical engineering and to me it seems totally interesting to have a degree for both fields. Is this something that is pratical at the professional level ?

computer science is compatable with almost all other fields, and at least some knowledge of other fields is required because programmers and computer scientists don't work/live in a vacuum. To answer your question, yes I can see a double major of computer science and mechanical engineering.

There is one further consideration: Both fields of study are difficult and time consuming: Unless you are brilliant or/and have much better study habits than most, you will need longer to finish such a double major than most students. Where I attended school, both degrees were in the Engineering department; where most students these days take 5 years to finish. I would expect closer to 6 for this double major.

When I was studying mechanical engineering back in the 1960's, Fortran was a required course. I am now a software engineer... :-) FWIW, my wife, the physicist, is one of the few people I know who still use Fortran, and mostly she uses C++.