The K11 does have a filter and it should be changed. It's about £80 from Nissan or £23 from this site where I get my spares. By the way nissan never changes this filter I think they just expect the gearbox to work for 100 000 miles or ten years with one filter...
Had a similar problem when my brakes failed 3 days after a full service and was found that the rear drums were faulty and never checked during service.I called dealer and they fixed it but wanted to charge 480 pounds.I paid but contacted the office of trading standards and they took all the...
I have the full K11 workshop manual from a dealership.its scanned from the books and in PDF (acrobat reader format).Ill be happy to send it to you via skype or email.Just email me at [email protected] to arrange it.