Why use OEM oil and filters?
All three of my Valks have K&N air filters.
I only use Shell Rottela T6 oil in my bikes (good practice).
I have used "SuperTech", "K&N", and yes,.....OEM oil filters.
No particular reason to be honest, i figure OEM isnt going to be the most performance but wont screw anything up either... That's good enough for me.
Of my 2 Valks...the I/S I bought new and all the while it was on warranty, I used only Honda oil and filters so if anything mechanical might have occurred, they couldn't blame it on my choice of oil and filters.
Ever since that warranty expired, I use Rotella T6 and just switched to yellow Purolator filters (painted flat black).