I ran a K&N on my Duramax until I had an oil analysis done. It showed everything normal except an elevated silicone reading. May need to find some type of foam filter that breathes more than the stock one.
K&N filter's aren't what they are talked up to be in my opinion.They dont restrict enough.They allow alot of dirt and particals to pass into the engine.If you do run a K&N you need to run a Outerwear,but why pay $50-$70 for that when you can get a UNI for $25 and have just as good of a filter that protects better and flows just as good?
Duramax,How does a K&N add Silicone to the engine? Do you mean Silica??
As far as filters go..If have to decide if you want more flow or better filtration..
Nothing flows better than the K&N, And it can filter well, it depends on how much oil you put in it and how much dirt collects on it, the dirt actually increases filtration..
The Uni-filter does filter better, but the cost is flow, it does not flow as well, it is a compromise.. not a bad choice, and certainly a bargain..but you can't have the highest flow AND the best filtration!!
Duramax, I will agree with your observation. I had a K&N on my 400ex when I raced and in dusty mx conditions it left a sandy residue in the intake tube. I switch to a uni and the residue went away. I have decided to stick with foam on the dirt.