I just put my '62 Volvo 544 back on the road after 35 yrs. I experienced rapid wear on new flat tappets using modern 10W30 oil. Not sure what caused it but only affected 4 tappets, both of cyl 1 and both of cyl 3. I replaced the cam and tappets. Would like to find suitable high zinc oil and viscosity for my car. Will drive only in summer, temps of 50 to 95 deg F. No hard driving. Don't need $$$ race oil!