nemesisjml, I have been using Mobil 1 15-50 in my 68 Camaro 250 for over a year now. I change the filter only @ 5000 miles, then change both oil & filter at the next 5000 miles. I have a convertible and ride a lot of girls in parades,staying in low for a couple of hours my temp has reached 250 degrees at times! the synthetics have great high temp qualities. That said,if I dont start for a week the lifters clatter like H***. So they don't solve all problems. Herb
