Stop in for a cup of coffee

really the point of my post about the oil viscosity was that the most important factor is temperature.
On a regular Chysler engine from the 60s, a 5W-20 at normal operating temps is going to be really thin.
It only makes sense to use a 5W-20 with normal bearing clearances if the engine is running really cold.
upload_2021-8-11_9-25-52.png