When my car was new, the black leather shift knob was replaced with a Lapis blue one. Seven years on, I still have the original knob in mint condition with the blue one on the car. The shift pattern on the knob has developed a yellowed tint, and the blue is coming off the leather. Some might look at this and say, gross, it is years of hand slime. I see it as a beautiful patina, like a set of old billiard balls, gracefully yellowed over time. I do regularly clean the shift knob and steering wheel, so they aren't dirty. I don't have any pictures right now, but the comparison is quite dramatic. Anyone else love this long term effect?