I've been liking QS oils. All of'em(QSGB, QSUD, DEFY)! Other oils too but, mainly QS! Good value and I'm liking the extra quiet that I've been noticing as well and no, it's not the placebo effect! I do notice this quiet with other oils as well...and some that are less so!
As-far-as filters! I'm still working on my stash of Purolator's(Classic/PureONE). Each one I've cut open after an OCI has been great but, they're from over 1 year ago purchase(sale/rebate/code# AAP) and I still have 6 of them to use. Until I get a bad one, I'll stay with them.