Max, If yer OEM filter is doing a good job than just keep on with what ya got. Another filter in the system will add DP that is unwanted and strain the system.As said earlier fuel additive is a huge bennifit for added lubricity,the centane improver in the additive will pay for the use of the product. Now additional oil filtration in my oppinion is a must with a diesel,My OEM filter is good down to 10 micron and I have a slip stream filter that takes it down to 2 micron BUT this doesnt do anything for soot in the oil, with all the extra fuel some of us are adding a toilet paper style filter would be of bennifit too.
Cheers, Kevin