I used Silkolean for +100hp applications when I could still get it...
90W gear oil works well and is cheap. Heck, that stuff even works on dirt bikes in the mud. The secret to chain life is frequent solvent cleaning (WD40 or kerosene) and lubing, it's really not necessary to go piling on tons of lube either (you're just gonna make a bigger mess). More is not better, frequent is. And if you lube a dirty chain, you're lubing the dirt too-get off your butt and wipe it down with wd40 before you lube. And last but not least, Don't forget adjustment. A loose or tight chain will wear out quicker too, never over tighten thats the worse, use your manual specs for slack.
Someone mentioned a gear oil with wax on top. BTW, that defeats the purpose of the wax (it never has a chaince to coat the rollers like its supposed to on a clean chain). And never ride with fresh wax, let it dry first-talk about a mess.