Valtra T170 problems

Hello ... I have problems with a Valtra T170 tractor for 5 days ... I explain what happened .... it works the entire season in September and October without problems and until today it has not given any motor failure ... nothing serious. I bought a new sower and went to take it about 5 km with the tractor. Before leaving I start the tractor and I see a lot of smoke by the escape a little bluish . I do not give importance because it is quite cold 8 degrees under zero. Upon arriving, it started to get a lot more smoke with a caliete engine and it smells like burned oil . At the first two cylinders a strong tacy began to be heard from time to time . It looks a lot