Diesel, I have been running my 68 Camaro 250 since 1980 when I bought it on unleaded Calif of course gas and have never had any head work done. I was told if the head had been run with lead since new tha there would be no problems. I typicaly drive 5-6 thousand miles a year. I tend to think that the no insert guys are right. Just my experence. Herb
