Oil integrity, API ratings and protection

[Kern Dog]

Today I stumbled upon a small stash of UNused oil in bottles that had no date code on them but did have the SAE API circle with ratings of SD and SF.
I thought that I was told that the higher in the alphabet the second letter was, the higher the detergent level.
In short, an oil like this:



 



...with it's SN rating is a MUCH higher detergent oil.
If this is true, what other characteristics could be said about this older oil? Is it possible that it may have a higher Zinc count as well?
I ask because I suspect that as the oil market adjusted to meet new car emission standards, they also included roller lifters that didn't need the cushion effect that was crucial for flat tappet engines.
I have 20 quarts on unopened "classic" oil that have either the API SD, SF or no rating at all. The oldest oil that I got is in cans!

I don't intend to use this in my red car. I use "Driven" oil simply because of the stiffer valvesprings and solid lifter cam.
I have a few other lower performance flat tappet cars out back that may benefit from an older formula of oil. They do all have softer valvesprings which probably saves the lifters and camshaft from excessive wear.
What say you? Do you think the lower detergent oil may carry a higher amount of Zinc/ZDDP ? How would it even be determined without an oil analysis?

[b5blue]

Try Google 

[Kern Dog]

Thanks.
I try to avoid them. I prefer DuckDuckGo for reasons I'll keep to myself.

[b5blue]

Have you Firefox?

[John_Kunkel]

I have read on oil-related sites that there is a shelf life of oil especially in plastic containers. Supposedly, moisture can enter the container through a process known as "permeation" and moisture causes some of the additives, especially calcium, to drop out of suspension. If inspection of the bottom of the container shows whitish granules, the calcium has dropped out of suspension and can't be remixed by simply shaking the container. It's still usable but it won't be up to spec.

[Kern Dog]

Thank you.
The cars I'd use this oil on have fairly stock engines that don't see a lot of use.
One is a stock compression 360 in a Dart, the other is a 440 in a Power Wagon.