Well it’s that time of year again. I am thinking about doing an oil and filter change on my 6.0L Diablo. I have always used Valvoline 10W-40 in the past. I have been thinking of switching over to Mobile 1 5W-30 synthetic. What do people think? I have heard that the Diablo engines were designed for "natural" oils and that one should not use the synthetics in these engines. I also was told one should use Valvoline because it contains more lead which coats the bearings. On the other hand I hear the synthetics hold up better over time. I typically don’t run the car hard. Change oil once a year. Do ~3000 miles each year (most in 90-100MPH range) in northern California climate.