I had to use some Pennzoil 20-50 in my twin-cam in a pinch. I'm changing it out asap...but I've heard such mixed reviews on using regular oil vs. bike oil. I know it will breakdown quickly (it was just temporary anyway), but will it still circulate the engine properly, or is it the worst thing? My bike still sounded, rode, and warmed up alright. I've been using HD oil until then...Any comments?