It wasn't so much the miles as i think it was the rpms.It would sling the lube out then it would stick.I used what (fisher) at that time told me to use. If I ran the rpms over 7000 it seemed to do it every time.So i was redoing it about every 3rd weekend of racing.I knew everytime it was getting dry the motor would shake or get ruff at idle or certin rpms i would feel the vibs.
But it was always a easy fix. I just got tired of having to deal with it.