I get about 6500 kilometers (two years of four-season cycling) out of my chain-ring, chain, cassette and pulleys before the drive-train beings to fail at which point I will have the entire drive-train replaced. I use the "chain slipping under seated pedal pressure" guide along with a visual check to see that the ring and cassette are worn down to nothing as an indication that it's time for a replacement. Winter is hard on components. I'd likely get more distance out of the drive-train if I did more than reapply oil. I'll chip away at the gunk when the chain no longer moves freely when backpedaling.