Over the years, about a third of our Tech line calls are about oil. We recommend a 50/50 blend of synthetic and petroleum based oils in Foley Tech Tip # 1. But a word of caution: don”t use synthetic oil during the critical initial break-in period. Many camshaft manufacturers and regrinders say not to use synthetics until the first oil change. Petroleum-based oil will enhance the break-in of the cam and lifters. At the first oil change, change the filter too to get rid of the molybdenum disulfide cam break-in lubricant. This goop while necessary for break-in, can easily clog an oil filter.