Is Mobil 1 a better oil to use than any other brand?

My personal mechanic says Mobil 1 is the best to use and he says he only uses it for his customers. He was saying the viscosity is better than Castrol or any other brand.

So my car is on lease so I have to go to the Honda dealer to get my 2017 Civic in. I ask for Mobil 1 5w-20 and he allows it but he says it may mess up the car and that he recommends using castrol. It is kinda weird because castrol was $30 cheaper than Mobil1 so i thought he wasn't trying to rip me off cause he actually wasn't.

He knows damn well Mobil 1 won't "mess up the car", he just has some other motive for recommending Castrol, probably because it's what they use.

Both Mobil1 and Castrol oils are better than the minimum requirements laid out by the manufacturer. You can't go wrong with either one. A lot of people have brand bias based on nothing more than warm feelings. If the certification of the oil meets or exceeds manufacturers specifications you can use either one with confidence. Conforming to the maintenance schedule for your vehicle is far more important than what brand of oil you use.

NO.

You're among the top ten stupid regular posters on this forum. The viscosity of oil you should be using is not 5w-20, it is 0w-20 and that's per the manufacturer. READ YOUR OWNER'S MANUAL.

Start getting a clue by doing your own research to educate yourself. Here's a head start…

http://knowhow.napaonline.com/recommended-oil-following-manufacturers-guidance-important/
http://www.carponents.com/content/oil-you-need-to-know-the-truth-about-motor-oil-165
https://newsroom.aaa.com/2017/06/aaa-spills-truth-oil-changes/

It's called "marketing". Your owners manual, which apparently you haven't bothered to read, and considering your moniker not surprising, states 0W-20. Any name brand oil of the correct viscosity and matching the requirements as listed in the owners manual you haven't read, will do just fine.

I thought everyone in USa used mineral oil and changed it every week.

You are not required to go to the dealer. Bring it anywhere and keep a record