Interesting material to read. Thanks.

Saw mention there that synthetic oil holds its viscosity better than conventional oil at high temperatures. Two comments:

• wouldn't 30 oil have a better viscosity that 20 oil at high temperatures?
• the higher the viscosity of the oil, the less fuel efficient it is.

Isn't the dog chasing its tail?

Motor oil is a complex system. Motor oil is not just a conventional base oil or a synthetic base oil. Either one would fail miserably at the job of meeting specifications without an additive package, which can make up to 25% of the actual product you put in the engine. Basically synthetic base oil and conventional base oil are carriers for an additive package that's the nuts and bolts of getting the oil concoction to meet specs.

about 80 percent of oil is actually oil. The other 20 percent is made up of additives

Say you weigh 100 lbs. Your head might be 20% of that weight, but a very important %age. The rest of your body is only there to carry your head around.

Additive packages aren't so simple, they are complex.
Additives in Motor Oil: Everything You Need to Know

Additives in Motor Oil: Everything You Need to Know - AMSOIL Blog

Additives in motor oil perform two critical functions: lessen destructive processes and enhance the beneficial properties of the base oil. Here's a rundown.

blog.amsoil.com

To make a long story short. From Royal Purple: Why Synthetics? | Royal Purple

A well-formulated conventional engine oil can outperform a poorly formulated “synthetic” engine oil. With that said, beginning the formulation of a motor oil with high quality synthetic base stocks does allow for a superior product compared to an equal quality level conventional motor oil.

The superiority shows itself in longer oil change intervals, that's about it.

 

An interesting motor oil presentation: Will thin oils damage your engine?