In the days when these 261s were new, 60 to 70k seemed to be a reasonable figure. I have a feeling that today's oils will change that figure to something much greater. We had a 1960 Pontiac from new with a 261 and it started smoking at about 70k. We has a "ring job" done and it was good as new. Oh, I forgot to mention that we didn't have an oil filter on it, imagine that!
