My airplane was parked for several years in NorCal. I don't have any knowledge on what was potentially done to it for preservation; I suspect nothing. I fully expect an OH in the next year or two. Just a question of when the cam starts making metal.
I doubt the filter will make a difference in that. However, I have read that a filter is better than a screen at preventing metal from getting into other engine components and causing additional damage to crank and cylinders prior to rebuild. Also seems like the filter might make it easier to catch the metal fibers earlier in the process.
OTOH, maybe the easiest and most cost effective move is to leave it alone and deal with potential accessory upgrades as part of the rebuild, when it happens.
I don't know when having an actual filter on an engine came to mean having an early warning system for when your engine grenades...
An oil filter will catch grit, carbon chunks and yes, even metals that are produced every time an engine runs. The old joke is "the oil screen will catch anything with a part number"...
There is a reason the suggested oil change intervals are doubled from 25 hours with a screen vs. 50 hours with an actual filter. A screen will hold back anything in the oil stream that won't pass thru the mesh unless the constant flow wears it down and forces it thru and into the rest of the engine. A pleated filter on the other hand traps much smaller particles and holds them in the filter insuring cleaner oil, longer.
As to how long an engine can sit before it's gonna need an overhaul; nobody knows.
If rust on cam lobes and cylinder walls is the yardstick being used I'd venture to say 80% of the aircraft engines at any given airport on any given week would be classified as junk...
I've had a Beech Mouseketeer (O320) sitting in a cargo pod for 6 years in Hungary get re assembled and flown for going on 10 years in the US. Ok compressions and nothing coming apart. I've also seen a IO550 put the #6 rod thru the top of the cowling @ 600 hrs. SMOH from a reputable shop.
Keep the oil clean and have a filter. If an engine that's been sitting will make rated power, not leak or burn oil and isn't making metal just run it. These little engines are pretty damn tough...
JMPO
Chris