Not all that critical for liquid cooled engines running low power applications (cars and trucks). It might last a few thousand miles more between oil changes.

Air cooled engines, and engines running >50% power for extended periods benefit more from synthetic oils. Most consumer “synthetic” oils are not synthetic, they are group III base stock conventional refined oil. The courts ruled that synthetic was a marketing term, and now everyone can call group III oils synthetic. They are still good oil, and better than group I/II oils, and probably perform as well as real synthetic oils in many applications.

“Real” synthetics are used in the most demanding applications, large aircraft piston engines and jet turbine engines. These will almost invariably be group V synthetic ester base oils. If it’s not $80/gallon, it’s probably not technically synthetic oil.