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I've found that the filter is more important than the oil. The zinc thing is something to consider these days but head to head, oil is oil. I'm talking a given 10W-40 versus another 10W-40, etc. Not a syn oil against a dino, or any other combinations like that.



You are right that motor oil filtration is an important factor.

The Society of Automotive Engineers (SAE) has known this for a while now.

See also: SAE Oil Filter Testing and Correlation Between Engine Wear.pdf - link

As for motor oil, if we are talking about comparing a non-race off-the-shelf name brand API rated petroleum 10W-40 to another 10W-40, probably not much difference there.

However, motor oil formulators have a vast menu of base oils and additives to consider when formulating a motor oil product. This goes for both conventional petroleum oils as well as synthetic oils. Based on a price to performance ratio, formulators can use inexpensive ingredients or high dollar ingredients to meet their objectives.

This is why some motor oils cost more than others; because motor oil is not created equal.

Retired VP of Marketing at the Hatco Corporation, Tom Schaefer, can explain this better than I can.

Excerpt from fom Schaefer’s article, What’s In Your Oil: Choosing the right components of the right chemistry in the right dosages is a real balancing act, as each of the components have their own pluses and minuses and can interact or compete with each other. Don’t try this at home - leave it to companies you trust who have the technology, R&D, and resources to achieve the necessary balance so critical to performance.

Read Tom Schaefer’s full article: What’s In Your Oil - link