In general, I didn't use to need to "clean"any of it. Cars and rollers needed it, not rails.
I'd wipe it going in and out of the box Nov and March or Aprl. most years. Sometimes with oil on the rag if it looked dry. The amount of black on the rag minimal.
It started to become needed when it came off the floor and went to a layout.
I attibute the majority of this wear to the Super O. And 50% of it was like new for tree use before it was mine, 50% on the same like new stuff +rough, but cleaned before install.
The tin can clip another possible cause of initial pitting and more likely imo. Once pitting, the dirty issue becomes almost redundant, arching is going to happen and breakdown increases. The question is how much for each case. I don't think we have enough constants to tell.
It's also showing wear on the rear rollers more than the front. I'd think the front would be dirtier from first contact and carry more current, more often being the closer path to the source, and would be the more likely to suffer electrcal pitting.
Angles suggestthe strike on the can clip would also be worse. Which leaves us with a rear roller who's metalurgy may be softer than expected, ànd showing wear faster, but that is only a line scale of time, and these rollers show more SuperO wear than tube wear imo. Electrical might be a possibility but I have to inspect my evidence more to be swung to that conclusion.
How do you tell electrical pitting from mechanical when you know the electrical molocule dirt and household dust vs layout's wear dirt would be so similarly bound? I likely can't. But I feel I can tie it to my other experience with electrical points and contacting and say "wear" louder than "dirt?". This is low/medium volt, medium current, indoor use. It would be the worst repetative scenereo of electro-pitting I've ever seen. And I know there are material differences in contact points, but plated steel contact isn't really all that rare either. I need to see fluffy carbon or stacked deposits.
There is a V cut in the bottom of the curved groove.
Higher, on both sides of the v channel, two bands of shiny flat show from incomplete seating in the V, natural because tubular has a larger dia. than the v channel. It can't wear where it can't touch.
Bottom line worst case scenario...is about 8 years of very clean mostly SuperO and like new shiney 0-27, and 2 or 3 of dusty S-O with some dusty time on 0-27 that seemed to do little to no wear untill the Super "wear" line was well established.
Another comparison, but using the dirt conclusion instead, might be that Super O has to be kept cleaner than any other brand for a roller to remain pit-less .
Metalurgy and wear seems more attractive as a possible issue now.
Regardless how, it happens and it's more of an issue than tube wear because of thrust angles and a sharper channel. It's still my favorite track but I see a slight issue is all.