I was just going to say that, Gil. Welcome aboard, Flames!
I didn't know about the "virgin oilchange" trick when I ran the Spec Miata enduro. I used a stock (of course) LS on super slicks, and pitted on laps 10, 20, and 30. I was about 30 seconds ahead of the second place car, and I had lapped one or two of the back markers. But I didn't get the lead until the 30th lap or so.
Drive smoothly, and remember it's not a sprint race. You've got time to pick them off slowly, without heroics.