For the past 25 years or so, I have used Pennziol 25w50 Racing oil exclusively in all my flat tappet engine cars. Never a problem. I ate a camshaft once before that when Pennzoil took all the ZDDP out of there street car oil 20w50.
Last year, after Pennzoil was sold to Shell, they discontinued the product and it is now unobtainium.
I did a pile of research on the Internet and decided that Valvoline VR1 Racing oil would be the stuff to use. Didn't want to start mixing my own oil etc. I looked at all the alternatives. There is a lot of junk on the Internet. But I bought $500.00 of the stuff to make the switch.
But just to be safe, I had the old stuff (of which I still have a bottle or two) analyzed along with the VR1.
Low and behold, it has only 65% of the zinc that the Pennzoil has. VR1 1304 ppm, phosphorus 1179 ppm. Pennzoil zinc 2014 ppm, phosphorus 1826 ppm.
I can post the reports as soon as my kid shows me how. But this is no bs, virgin new oil samples. So forget any hype you read elsewhere. "designed for flat tappet engines" etc. All bs.
My question to the gurus is, now what? I know I am not the only one with this issue.