I am in complete agreement that synthetics "find" leaks rather than "creating" leaks; however I have heard that the blend oils don't have the same issues. I now have Mobile 7,500 blend in my 85 that developed a massive leak when I tried Castrol Syntec so I will report if it leaks.
As a side note, the Castrol Syntec is a group 3 base oil and is 100% purified dyno oil. Mobil 1 is made in the lab (PAO base oil). I don't know if blends are a mix of conventional and synthetic or just a purified dyno, I suspect it varies with the manufacturer.
