Quote:
Originally Posted by Synchro909
And therefore Zinc (ZSSC) is required but did the oils of the 1920s have zinc added?.
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No, zinc was added with higher reving motors to reduce wear, due to higher reving motors needing stiffer valve springs so the valves would not float.
You probably already know, Zinc has been mostly removed because it was found zinc damages catalytic convertors. Am not sure thought I read that Zinc was also hard on some sensors.
Only diesel oil has much Zinc in it since diesels do not have catalytic convertors. There maybe other reasons for diesels having zinc oil, but can not remember why.