Oil Oil and Zinc

Do not use a zinc additive if your car has a catalytic converter. It will coat the converter with the additive and ruin it.
 
a stock Model A. not enough spring pressure to worry about zinc.

a good quality oil on initial start up and run the engine a a bit of elevated RPM so oil will splash all over it. your good to go
 
old ugly said:
a stock Model A. not enough spring pressure to worry about zinc.

a good quality oil on initial start up and run the engine a a bit of elevated RPM so oil will splash all over it. your good to go
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The above is correct! Also coat the cam lobes and lifter bottoms with break-in lube or lithium grease during assembly. If the engine is already assembled, don't worry about it.
 
OK, but even with less pressure doesn't the zinc help to extend the life of the engine? There are other wear points in the engine that it may help.
 
Fullraceflathead said:
It cant hurt it but not required.
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It’s not that simple. Because if the dosage is too high, ZDDP causes significant harm.
There are—at least in Germany—special vintage-car oils with API classifications "SB" and "SC" that already contain an adjusted level of zinc additives. Adding more causes damage.
As correctly noted above, oils for modern engines must not contain such additives due to the catalysator, fuel injectors, and outlet-valve stems.
They are ill-suited for use in older engine designs that typically consumpe oil.

 
I agree if you add the additive to the older oils that have it you would have excess additive but the more modern oils have very minimal amounts of it so adding it shouldn't give you a imbalance you definitely wanna follow the recommended dosage on that can instructions
 
The container for diesel oil says "not for use in other engines", or something like that, because more zinc is used in diesel oils. In the 30's, zinc wasn't used in engine oils, it wasn't needed.
 
Jim Brierley said:
(...) In the 30's, zinc wasn't used in engine oils, it wasn't needed.
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Jim, let me please put it another thinkin' way.
Back then, the phenomenon of boundary lubrication provided by ZDDP-induced phosphate formation had not yet been researched; that insight was gained around the time of World War II time.
It was then utilized in oils designated API "SB"—the first oils to feature wear protection.
It is also worth noting that leaded gasoline was used at the time. Tetraethyl lead is another substance that facilitates excellent high-temperature lubrication.

Modern engines are optimized for precise tolerances. They consume hardly any low oil consumption and can therefore use a completely different additive package. The Model A engine will suffer from sludge buildup if modern oils are used.
 
No, that’s not what I meant.


Not oil sludge deposits, but hard combustion residues caused by the additives when the engine burns oil. In the combustion chamber, on the exhaust valves, and on the piston crown and the top land.
 
Guys, Modern oils have zinc in them, just not as much as diesel oil. Modern oils will keep the engine clean, non-detergent doesn't keep the sludge out of the pan, valve spring area, etc. I have worked on pickups that have bee using non detergent oil, and the sludge was so thick that the oil didn't drain back into the pan quick enough, and it starved the oil pump. If you use modern oil in a car that had non detergent in it for years, detergent oil will clean the engine, so you must change oil frequently or you'll have trouble. I use 20-40 oil, brand makes no difference as they must all meet the same standard. I also use PPO in the gas to lube the valve guides, etc. Modern gas is dry, and I've experienced a stuck valve in my old tractor because of this.
 
I was wondering if you meant marvel mystery oil!!! Jim at no matter what age you are a treasure chest of knowledge to the Model A community!!!
 
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