"Lubriplate" (with an 'i') has been around a long time. Some, but not all of their products are branded as plastic-compatible. So for the last 25 years or so, I've been using Labelle 106 with Teflon.
The MPC New Haven F-units are very high quality trains, and were GREAT runners when they came out. I would endorse them with or without plastic gears.
I played with MPC trains growing up, and for a long time afterward. Even after a decade of childhood abuse, high-speed reversing, etc., we personally never had any failures of the nylon worm wheel, or the nylon spur gears on the side of the truck. I'm not saying that it never happens, but metal gears can split too. I've come to conclude that the plastic vs. metal thing is more about the perception of quality than actual performance.
