[Captain Chris]

5w30 or 10w30 in all 4 of my Fords, never burned a drop or leaked a drop. I won't use 5w20, it's for a slight gas mileage increase so they meet standards. And the tolerance thing is internet bull. Motors built many years ago had the same or even better tolerances on internal engine parts. These days tolerances are crap, ask any Subaru owner or Jeep 2.4 owner how much oil their cars burn.

If your car is still under warranty, using oil not according to the manual/book can void the warranty on the engine.
After that, it's a free country!

But tolerance issues are not "internet bull".
Do manufacturers have different priorities than you do? Yes.
Do manufactureres have different priorities today than they did 10 years ago?
20 years ago...?
Etc...
That is nothing new.
Engines today are different than 20 years ago; which are different than engines from 40 years ago; which are different from engines 60 years ago...and for many different reasons.

Engines & drive trains are guaranteed for a certain service life, and the objectives are to have some fairly high percentage of them survive beyond that, in order to minimize overall cost of warranty services, and support, to some extent, resale value of the vehicles.
Tolerances on engine assemblies, and versus lubrication needs are a real thing that engineers study and can specialize in: I know, because I studied it in university, though I did not specialize in it.
Of course, just because an engineer does some calculus, does not mean that the engine ends up being built exactly that way...

That being said, I am not impressed with with the idea of the super small turbo engines they started putting in lately, and it would appear that they are doing worse than I expected...

But do what you gotta do...

 

[Captain Chris]

Here's the deal: 'Multi-weight' or 'Multi-grade' oils are formulated to have specific viscosity, or flow characteristics at certain temperatures: a 'cold' temp', and a 'hot' temp'. The higher temp' is specified in the test standards, based on engine operating temp's but, fast-forward ~50 years, and that's become even more variable.
Todays engines are designed with tolerances, and part of that is to allow for oil flow through, and between moving parts.
When the oil gets hotter and thinner, it may not maintain a film layer between moving parts, however, if you use higher viscosity oil, you may have a problem with not having adequate flow when it is at normal operating temps...
If you are running in the heat all the time, you are still probably better off addressing that: installing a different thermostat valve, as well a discreet temperature gauge, upgrade cooling fan under the hood, and look into getting a lower temp activation switch...also, look into changing/adding radiator capacity.

Keep the engine temp correct, and stick with specified oil.

Good luck!

 

[Captain Chris]

Yes, car makers (or any equipment manufacturers) don't want their products to last forever; but well all know that if some product gets the reputation of dieing within a couple months after the warranty expires, then, that is going to impact the new car price, as well as the resale price...different products have different consumer distributions, and so they are designed with consumer sensitive life-cycle projections...
As for the CVT, I don't think that technology was 'road ready'...might never be...