Z170 is the correct filter
(Although some use the Z9,i dont and never will)
They are a pain to do where they are
If its something that has happened on the last few changes ,sounds like the surface area is not flat or somethings making it not seat up properly
If its just on this one,maybe something (dirt, grit,ect)has got on the seating seal while trying to get it fitted
If the thread is cross threaded,surely it woud be noticeable
(Although some use the Z9,i dont and never will)
They are a pain to do where they are
If its something that has happened on the last few changes ,sounds like the surface area is not flat or somethings making it not seat up properly
If its just on this one,maybe something (dirt, grit,ect)has got on the seating seal while trying to get it fitted
If the thread is cross threaded,surely it woud be noticeable