So What Should I Do?
The following guidelines can help you prevent cam/tappet failure and protect your engine.
Initial Break-In Period (First 30 minutes): Use oil with ZDDP at 0.14 to 0.15 percent by weight (1,400 to 1,500 PPM) to provide the additional protection needed to maximize the chances of a successful cam/tappet break-in.
First 500 Miles After Initial Break-In: After that initial 20- to 30-minute break-in period, change the oil and oil filter. The oil you run after break-in will not need as much ZDDP; 0.10 to 0.12 percent ZDDP will provide protection without risking chemical corrosion.
Second 500 Miles After Initial Break-In: After the first 500 miles, change the oil and filter again, using oil with the same ZDDP level, 0.10 to 0.12 percent.
After the First 1,000 Miles (Car Driven Infrequently): If you don’t drive your car once a week for 30 minutes or more with the oil between 170 and 200 degrees, consider using oil formulated specifically for classic cars. This oil has a mixture of additives designed to deal with the moisture, corrosion and acids in engines that sit for extended periods of time. Change your oil every 3,000 miles or every six months, whichever comes first. If you live in an area with high humidity, change the oil and filter four times a year.
After the First 1,000 Miles (Car Driven Frequently): If you drive your car once a week for 30 minutes or more with the oil between 170 and 200 degrees, you have more options. Driving the car frequently will minimize the amount of acid, water and water vapor in the crankcase, and that will limit the corrosion and subsequent pitting of the cam lobes and lifters. Using 20W-50 API SM oil with 0.08 percent ZDDP can be fine, but if you are more conservative, a ZDDP level of 0.10 to 0.12 percent will provide additional protection.