Royal Purple 10W30 (non XPR/RP51), and WIX (Napa Gold) or Purolator Pure1 filters are and will be all I use on my Z31.
I ALWAYS advise people against using FRAM or Quake State filters.
I try to tell them to get Napa Gold filters, but do they listen? no.
WHY?
#1 Excuse: "It's too far for the nearest napa".
8 km is SOOOOO far for something that will prevent engine damage. Yet they fail to realize that if the engine goes, it will be the one thing stopping them from going to Wal-Mart or Canadian Tire to purchase that self-destructing FRAM.
Anyways... Stony, hate to see this stuff. I think you've probably been through more bull-crap with your engine than anyone else has on their entire car in most cases. Not to mention your chassis fiasco too.
Hang in there man. It will be worth it, and if you quit now... a lot of us will realize we're under a security blanket called "support" and "inspiration", and it can fly away at any one time!