That's why some oil ... additives are not strictly necessary. However, if you own a vehicle made during or before the 1980s or one with a vintage-style, high-mileage, or high-performance engine ...

we believe vintage engine are normally better served by heavier 10W-30 or 20W-50 synthetics. When it comes to engine oil additives the most was ZDDP, a combination of zinc and phosphorus.

But engine oil never wears out. It gets contaminated from combustion byproducts and it loses its additives to heat and ... Without zinc in the oil, wear for vintage engines with flat tappet ...