I recently got a new to me 2017 Mini Cooper S. Its a manual with 40k miles.
I am reading that these b48 engines can take a wide variety of oil types.
I am looking for recommendations for hot weather since its usually over 100 degrees here every day (with +50% humidity).
5w-40 perhaps? I cant find any other forums that talk about oil usage in high temp climates.
I will be doing the oil changes myself as I do them for all my cars.

 

Oil threads on forums are always interesting. Lake Speed has a bunch on YouTube videos about oil and the science in the formulations. Its Lake Speed Jr i guess. His dad was a race car driver from the 70's and 80's. A lot of marketing in oil and additive packages. My Mini is a hobby car and I also have a Mustang. I run Royal Purple 5w 30 in both and both cars are summer only. I have a Toyota that runs something silly like 0w-5 and that seems like witchcraft. Light oils help meet MPG standards. The mustang calls for 5w-20 i think. Like i said I just run the 5w-30 in both hobby cars. The Toyota i take to get serviced so it run factory recommendation. you will get a lot of different opinions on oil.

 

Ambient air temperature and engine operating temperature part company when engine temp exceeds ambient. Just whatever the manufacturer recommends.

 

What @Fly'n Brick said. Start with the manufacturer recommend. For a 2017 Cooper S (I have one) BMW recommends an oil that meets BMW LongLife-17 FE+ spec. When the engine temp is above ambient temp it's the engine temp that is going to matter.

 

If (if) MINI sanctions say 0w-20, 0w-30 oil you could consider using 0w-30 oil. I had another German car -- several in fact -- for which the factory sanctioned 0w-40, 5w-40, and even 5w-50 oil. However, one big important restriction was if the car was used in cold climate conditions (<17F / <25C) temperatures 0w-40 must be used.

While where I lived didn't get that cold it did get hot up into the triple digits and I switched to using 5w-50 oil. The 5w-50 oil HTHS number was a bit better than the 0w-40 oil I had been using. However, I used 0w-40 in these cars for tens of thousands of miles in ambient temperatures of 119F with no problems.

So the switch to 5w-50 was more an imagined need than a a real need.

When I lived in CA for my 2018 JCW I just used whatever oil the dealer service department used. 0w-20 I am pretty sure. Then (this after I moved away from CA) and I then owned a 2022 S and a 2023 JCW the local BMW dealer used the MINI oil, 0w-20.

So no need to overthink this. Just use the oil the factory recommends. US auto makers do hot weather testing in the southwest US. Some German car makers hot weather test in South Africa. But I seem to recall reading of new MINI models being tested in the southwest US. (They can also be tested in the UAE.)

Thus the car/engine and oil have been subjected to extreme hot climate conditions.

 

.
When it comes to very high temps and speed, HTHS matters.
If so, forego everything "FE". No LL-01 FE, no LL-17 FE+ etc..
Just run BMW LL-01 (not LL-01 FE) or LL-04 instead.

It doesn't matter if it's 0W-30, 5W-30, 0W-40 or 5W-30 as long
as you don't live in Minnesota or Alaska (winter). All of these
come with a minimum HTHS of 3.5 mPas (if it's LL-01 or LL-04).
The 30 weight oils are at the high side, the 40s are close to the
minimum to meet BMW's efficiency requirements (for low drag).
Many if not most LL-01 use to come with MB 229.5 and some
with Porsche A40 simultaneously. Many if not most LL-04 use
to come with MB 229.51 and 229.52, VW 504 00 (30) and with
Porsche C30 or VW 511 00 (xW-40), some with Porsche C40.

See for Mobil 1 ESP 5W-30 at your Walmart. It has a very high
reputation. I run it on both of my cars. True approvals such as
BMW LL-04. MB 229.51 and 229.52, VW 504 00/507 00 and
Porsche C30.
.

 

in Central Florida I go with what Mini uses. I don't do oil nomo. I can ask next time I'm there ?