I must agree with the Oil Geek, but can't stand his presentation style. As an engine oil formulation chemist with Chevron for 18 years, and may years doing the same for other companies, I do understand oils and oil formulations. For background, ASTM sets the requirements for automotive engine oils, ASTM D4485 Standard Specification for Active API Service Category Engine Oils. The requirements include 6 engine tests measuring oil oxidation, sludge and wear, fuel economy, and timing chain wear. The cost for running and passing all these test requirements is well over $1 million per engine oil formulation. On top of this are at least 10 laboratory tests. And then engine manufacturers often have additional criteria and tests that are needed to meet Factory Fill performance such as GM Dexos which requires additional performance at high engine oils temperatures. Think 64 hours running at 300°F oil temp and that will give you an idea of the severity of the testing.
You then apply for an American Petroleum Institute (API) license which allows you to put the latest engine oil category label on your bottle, but they monitor your product with periodic sampling to be sure you are not skimping on the formulation.
But this gets you an oil that is suited for a modern engine (2010 and newer, say) and not well suited for an old engine with a slider follower camshaft. For my older cars, I use Heavy Duty Diesel Engine Oil such as Delo 400 or Shell Rotella T SAE 15W-40. It has sufficient zinc to protect cams and has more dispersant and detergent to keep a gasoline engine exceptionally clean.
I should criticize the Oil Geek's selection of PAO (Poly Alpha Olefin) synthetic oil for the blend testing as PAO in actual engine oil formulations requires another blend component to help additives dissolve in the PAO as it is a lousy solvent whereas conventional base oils are fine solvents for additives. So even the Oil Geek can misrepresent reality.
There are a number of oils marketed for older cars which contain higher Zinc content. They should work fine if from a major oil marketer, but they are not covered by API classification requirements so there are no industry standards for these oils. More risky, so stick with a company that will stand behind their product. This is one reason I use HD Diesel engine oil as it is produced to API requirements and backed by major oil companies. SAE 15W-40 works in older engines too and is just slightly more viscous than SAE 10W-30 which is what most engines used back in the day. You can get HDDEO in 10W-30, but it is usually a special-order item from an oil marketer and not a retail store.