Companies pay ALOT of $$ for people to research what kind of oil fits with what kind of engine.

Each company name just add different additives into the mix to make the oil " their own". As long as the oil you are buying is CERTIFIED, it is good to go. So It only depends how much you are willing to spend. When I know I need to buy oil, I wait until it goes on special at the store often @ -45% off, then I by it. As long as it meets the requirements, even if it's cheaper, it is all good.

Of course I would like to always buy the Mobil 1 or that purple bottle, but I've always used 20$ oil and never had any problems really. Always changed it when it was supposed. Every 8,000 km in my world

Yea, use what viscosity (wt) the vehicle calls for under the driving conditions it's in.  As a note for those interested, check "Project Farm" on YT as he did some considerable testing on oils (HillBilly style) and even tho there was a winner, they're all pretty dang good these days.  

I run Mobil1 oils in my vehicles. As far as consumer grade driving goes, anything you can find in a parts store will work fine, so long as it's the correct weight and viscosity for your engine. As far as filters go, I would definitely spend the extra money to buy a quality, name-brand filter.

The notion of buying more expensive oils to last longer is not correct. Most expensive oils are as expensive as they are because they are designed to withstand heat and abuse better (say constant full throttle pulls on a race track for a couple hours). This is why a lot of people who track or race cars like these oils.

I use mobile1 no problem so far. You can use any oil brand as long as it has the api seal and always use the recommended weight by from your owners manual.