Is it ok to put a K&N air filter on my stock 2005 LLY?

yes.

make sure that the oiling is on the lighter side, no heavy soaking of the cloth. if you get the SES to lite, it will probably be a MAF code; use a MAF cleaner or even cab cleaner will work.

Take a look at the Air Filter Study (http://www.dieselplace.com/forum/showthread.php?t=117009).

I would recommend staying with the stock filter. You won't see HP or Mileage gains out of a K&N. But if you do go with the K&N, just be prepared for a dirtier engine, lighter wallet, and more time spent servicing filters. ;)

yes.

make sure that the oiling is on the lighter side, no heavy soaking of the cloth. if you get the SES to lite, it will probably be a MAF code; use a MAF cleaner or even cab cleaner will work.

X2. I do oil analysis on my truck and run extended changes and my silicon level is very acceptable and my wear is excellent. I have used K+N's since the early 80's with zero problems. If you are buying it for performance it is a waste, if you are doing it because it last the life of the vehicle then it is well worth it. Have a good day.

I ditched my K&N and went back to AC Delco paper filter because of the referenced air filter study. Fuel mileage actually went up over 1 mpg with the paper filter. :)

stick with a donaldson filter.