[Aarongriffey]

The number of cylinders has nothing to do with the flat tappers wearing out the cam and lifters.
I’ve replaced cams and liters in several 4 cylinder cars. All were push rod engines.
You can keep believing that the zinc scare is just to get your money if you want.
About 15 years ago, before the no zinc scare, a guy her in Oakland picked up his rebuilt 350 Chev engine from the machine shop, took it home and let it set on his garage floor until about 6 years ago.
When he finally got around to finishing the job he claims it lasted 20 minutes before it got noises and running rough.
I saw the cam and lifters after he brought the engine back and the machine shop tore it down.
One cam lobe and it’s lifter we’re so bad the valve was no longer opening.
The owner said he never heard about the no sink danger. When he picked up the engine some years earlier the machinist didn’t know time would come when there would not be sink in the oil.
Supposedly after break in sink is not required, but last year I replaced cam and lifters in 350 Chev pickup that had around 80,000 miles on it. Every cam lobe was worn down and the liters were all scored.
The last one I did was about 6 months ago, an MGB, the owner says he always uses the additive. Each lobe was worn down .030” on the high spots and only one lifter was slightly pitted.
In the past 5 years I’ve seen more cars with a lobe or gone completely than I ever saw in the first 60 years of doing that kind of work.
You guys that think it’s all BS, keep thinking it, I need the money.