Ok its very simple. The only way I would bother with chain lube is if I had a scot oiler. You will nor get anymore miles out of it, and it slings the crap every where other wise. You can regulate the scot oiler to put just a few drops at a time on so that it keeps the chain nice and wet looking without it slinging off. I look at my chain every time I get on my bike but I know what I am looking for. basically you want close to and inch of play right in the middle of the bottom of the chain. Inother words you hold a tape measure up to the chain and lift it if it goes to an inch good if not to tight if more well that different. I wouldn't adjust it unless it moved closer to an inch and a half. Now the disclaimer Thats me and me alone follow the advise if ya want. If you want more opinions others will chime in eventually.
Like Ian I think that dirt and road crap sticks to the "lube" and wears the sprockets. You see you use "lube" oil on cutting instruments to cut faster when cutting metal and to cool the cutting blade and metal. Cooling the cutting instrument keeps it sharper longer,
so it cuts more efficently
