The new vehicles will tell you several things. Most will tell you to change the oil at 5-6,000 miles, or when the oil change light comes on. You cot to remember, the ones telling you this are the ones changing your oil. The more frequent you change it, the more money they make! Try the Mobil 1 Extended Performance, and change the filter and rotate the tires EVERY 6,000 miles, and then change the oil and filet, and rotate the tires again at 12,000 miles. We have 600,000 miles now on synthetics, mostly Mobil 1. The 99 Silverado Z71 now has 198,000 ALL on Mobil 1, and most on M1 EP. This is my standard routine for non boosted cars. The boosted cars, I CHANGE the oil at every 5-6000 miles, along with the filter and rotate the tires.

Rotating the tires every 6,000 miles is THE one most money saving thing you can do for car maintance. And when you do your tires, check pressures, and HAND TORQUE the lugs to 100 ft/lbs, and DO IT AGAIN after 50 miles or so. Mis-tightening lug nuts is IMO THE #1 cause of vibrations and warped rotors. Get rid of the impact wrench!

Another opinion, conventional oil was OK 100 years ago, but times have changes, and for the better. Synthetic oil are one of the ways things have improved.

 

I've used both and honestly can't tell a difference between the two so I'd say get the one that costs the less.

 

It really comes down to if you want to adhere to the warranty approved lubricants or not. There are only a hand full of approved oils for supercharged, turbocharged, and other high performance GM engines, GM8417 certification, Regular Mobil 1 is approved, but Mobil 1 Extended performance and Royal purple are not, and IF a major engine problem were to occur, GM WILL NOT cover the repair if a non approved lubricant is in your crankcase.
In a non high performance engine, ALL of these lubricants are approved, I believe.