Engine oil

[Bob Culver]

I am not sure there is a definition of a straight oil. Some take it to mean monograde. Some mean without any additive. The virtues of detergent are debatable although most oils have been since the 1950s and millions of cars without filters on the roads then and since, many with previously accumulated sludge, have used detergent oils often without even a clean of the sump.

Again I quote the later Beetle ; no filter, detergent oil, although did have a magnet.

The absence also of other modern additives; anti wear, anti acid, anti corrosive etc reduces oil to SAE SA or SB quality as typical to early 1950s, when wear was commonly several times today. I can recall the sump of our Seven around 1950 with an inch of grey sludge and main bearings rumbling at 10,000 miles. Doctors cars used for short runs were notorious for bore wear. Mere SE and later oils were a huge improvement. Oils can be too classic.

Modern medium and cheaper oils very superior to SE and wear very low. No Sevens will achieve 300,000 more miles, or will suffer mechanical failure before, so the nil wear of modern engines running top grade oils seems somewhat academic.

Most Sevens burn oil, do small mileage, have time based oil changes, so the expensive modern oils intended for very long service an extravagance.

Er, for SAE above read API