I used silicon spray on my MTB when I lived in a sandy area. It kept everything VERY clean. You do need to apply it every ride. You can get a can twice the size for half the price at Wally World.

I tried Prolink for a while. then, White Lightning. I found WL to be cleaner. That is what I am using now, but I might try the silicone on the road when it runs out.

The big reason that you don't want motor oils is that they are formulated to HOLD contaminants. This carries them away from engine parts and to the filter. It just makes for a dirty chain on a bike.