On storage, it is what it is, a non-climate controlled loft above my garage. Sub-zero to hot. The zinc rot was first found in K-Line and Weaver die cast trucks (relatively easily substituted). The engine zinc rot was on drivers of a RailKing loco (others on this forum have experienced rot on the same model). I haven't located replacement drivers and I have heard that the drivers are not meant to be pressed on and off. I can probably find the same loco on the bay for the cost of replacement driver parts, but that is good money after bad. Into the trash. I haven't unpacked additional locos from the same era but I won't be surprised to find the same problem.
On oiling, I run a Peerless steam tractor in the summer and the rule is, if it squeaks, oil it. Same thing in locos and cars. I grind hyperdermic needles square and can get a minimal drop where it is needed. What needs a tiny drop every year are pickup rollers and the wheels that squeak to let you know they want attention.
On electronics, I purchased a lot of Proto-1 when it first came out and many of these early QSI boards suffered from the death rattle issue and repeated attempts to do a chip reset have been inconsistent. I bought a couple of early Proto-2 locos, one went back to MTH for repair but their QC was non-existent back then. That engine loves to send me Check Track status. Of all of these, the only ones that may get a Proto-3 conversion is the Proto-2 loco in the hope that a board refresh will correct its ills. The rest of them will probably get a bridge rectifier and some dropping diodes so they can run conventional in one direction (w/o sound). Some of our shows have a loop dedicated to conventional locos dragging a long freight for hours so I'll put a lashup together for that.
I keep grudges that form when a manufacturer ships a thousand dollar+ locomotive with manufacturing defects and can't seem to repair it successfully. I stopped buying Lionel in the '90s for that reason. I stopped buying MTH after my frustrating experience with early Proto-2 locos coupled with the polymorphic DCS signal failures my club was experiencing. (For several years, it seemed that the only engines running in the first hour of a show were conventional and TMCC as many of the DCS engines seemed to need reprogramming on the club's TIUs to run reliably on the show layout).
It was only when Lionel introduced Legacy with a Daylight loco I wanted that I bought a new engine from them. I was immediately hooked on the sounds (esp. the quilling whistle) and excellent low speed operation. (And it could smoke!) The visceral experience running that engine was far better than running my Proto-2 locos (when they were behaving themselves).
Since Lionel also publishes their protocols, I have applied my day job experience with embedded systems to write software that monitors the TMCC protocols, and soon, will control the Legacy locos. I am a happy camper with Legacy. MTH has a closed system and offers no means of a 3rd party interface.
But the Joy of owning and operating these electronically controlled locos is short-lived when they are unrepairable. I used to run a repair clinic at our train shows where I could resuscitate pre-war and post-war locos with cleaning, oiling, and (far too often) an E-unit rebuild. Had a parts guy with me so we performed magic on site. But when we found a bad electronic controller (don't stock those), the repair was halted and we told the owner where to call for parts and showed him how to install the board.
I suspect that my older Legacy locos will eventually fail and repair is not feasible or economical. I am now resigned to the fact that our hobby's future is disposable products with an unknown shelf life far less than we have with our classic conventional locos. I will prune my roster to a minimum, run the wheels off the locos I keep, and buy a new engine only when an existing one fails. Both Lionel and MTH have stated that they want us to buy the latest models instead of supporting the older stuff, and the rapid obsolescence of electronic components used in their boards is probably a big factor in their strategy. That being so, don't expect me to build a huge roster of you engines anymore.