I've been researching engine oil for an article I am writing for the ACCCC car club. Club members have cars dating back to the teens and many could use more information about the oil they use in their cars. I understand that non-detergent SA engine oils were used in cars up until 1930. Castor oil was/is a excellent lubricant for these engines. Starting in 1931, additives were introduced (SB oils) to combat sludge. An earlier post on BITOG provided a link to the following study: Slide show of SA oils in modern engines 2004 I believe cars of the 1930s had to contend with the same sort of problems with sludge. I'm not sure if they had the same sort of wear issues though. Exxon Mobil clearly believes that synthetics (including Group IV?) are suitable in older engines because they mention it being used exclusively in a 1955 Chevrolet pickup: Mobil 1 TV Ep 2: Debunking Myths About Synthetic Motor Oils However, in the 1931 Ford Model A thread, Johnny writes the following:
ExxonMobil and Johnny apparently disagree on the use of synthetics in older engines. Perhaps EM should have explained how old. What sort of seal incompatibility would someone expect to experience with the use of a PAO/Ester-based synthetic? Has anyone used synthetics in engines dating back to the 1930s and 1940s? If so, what oil did you use and did you experience any problems?
Originally Posted By: "Johnny"
I would surely want him to use a modern oil, but I would not recommend a PAO/Ester based synthetic. Talk about seal incompatibility. I would recommend something like a Rotella, Delvac, or Delo straight 30W for that little jewel.