No plastic wheels for years Doug. Even had to change out most of early metal wheels with plastic axles as they lost their true and became problematic for derailing. Now only use metal wheels with metal axles.
Some locos/lighted cars with suspected wiper/bronze bearing pickup problems did get sparing applications of Conducta Lube or thinned NoOx with improvements noted. Used to clean track/wheels with 91% IPA until someone mentioned that it promotes oxidation, which explains why it only worked for a day or so and left more black crud. My rails are indeed "ribbons of steel", as I "gleamed" them about a year ago and have only used silver polish to clean them since. But even that would only work reliably for 3 or 4 days. Got to be I spent more time cleaning track than running trains and was thoroughly bummed out.
That brings me up to the CRC 2-26 sparingly applied with dry wipe every 6 days or as long as I can go without experiment. I honestly don't know how long this improvement will last, but it is better than it was. Don't know what the "black crud" is, but its not metallic gray like I would expect to see with metal wear. Its black and I keep thinking carbon. Maybe the hi frequency DCC current and/or arching is disassociating the C from CO or CO2 in the atmosphere.