I use anything that is cheaply available at that time and that has an additive-package which I deem to be appropriate for my engine backed by existing oil analysis.
In the past years, I've been running oils made by Valvoline, Gulf, Castrol, Meguin, Mannol, Q8-Oils, Ravenol and others...
Some were mineral-based ois, some hydrocracked, some pao-based and some even pao-ester-based. Viscosities ranged from 5w-40 to 15w-50.
The engine happily takes everything, one of the perks of owning an older vehicle...
Currently, it is 31 yrs old, with just about ~115k miles at the moment and runs very well. It consumes about a quart every 5-7k mls and the valve-train is very clean.
https://m.imgur.com/a/NlByhNW
For the next summers, the car will be using Penrite Racing 15 15W-50. I have a bulk of it sitting in my basement which I recently acquired for 3€ / liter in a closing sale.