Quote:
Originally Posted by DD931
Thirty weight viscosity oil was the thing in 1930. Detergent oil had not been even conceived, let alone invented. Same thing for multi-viscosity. From my perspective you should be using a modern oil. New engines are much more demanding than our old flatheads and lubricating oil technology has moved ahead with those designs. I know it's not a Model A, but I have a '48 F-1. Its owners manual recommends using "Heavy Duty Motor Oil" stating "The heavy duty motor oils contain detergent compounds and tend to hold in suspension the foreign contaminants which normally would deposit on the engine parts." It goes on to say "This term shall be used to designate an oil having proved oxidation stability, bearing corrosion preventive properties, and detergent dispersive characteristics. Oils of this type are generally suitable for use in both high speed Diesel and gasoline engines under heavy-duty service conditions."
Detergent oils were just coming on the market at this time and were considered in the high end of the market. Now, of course, all regular oils are detergent. Detergents in the oil prevent the formation of sludge, which I consider highly desirable. If you pull the dipstick on a modern engine the oil will not show any sludge formation. Wouldn't you like your 4 banger to be like that, too?
I use 20W-50 multi-viscosity. Others will have different opinions, but don't fall into the single viscosity trap. Again, following the above logic, modern multi-viscosity oils maintain the desired viscosity over a wide range of temperatures. These were not available in the old days.
Then there's the Zinc trap that old-time "gurus" fall into. This has been the subject of much heated discussion. In my opinion there is more than enough zinc and similar additives in modern oils to keep your banger happy.
Does a Model A place demands on motor oil that are more severe than a modern high performance automobile engine?
JMHO.
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I too was in the needs zinc crowd. Modern flat lifter engines do need a zinc additive like the jeep 4.0 and chevette 1.6. Model a days oil didnt have zinc and the valve springs are nowhere stout enough to require zinc.
Modern multi weight detergent oil is way better than non detergent single weight. Most of your engine wear happens at startup. Why would you not want the oil to flow quicker especially on a gravity splash oiling system?