My semi-educated guess as to why JLR (and some other automakers) specify 0W-20 oils in some of their engines is that they are chasing the highest CAFE numbers that they can reach, which is also a reason that they have that silly engine start/stop feature.

I live in the Southern California mountains and the temperatures do sometimes dip down below 30 degrees F. However my Jaguar won't ever leave the garage during those times as I have a Mazda AWD SUV for driving in frigid or inclement weather. In the summer months, daytime temperatures in the nearby valleys or desert areas that I may traverse can exceed 105 degrees F or even peak at about 115 degrees F. The 20 weight part of that oil seems a bit thin in those circumstances and the 0 weight part doesn't seem necessary if I am not driving in sub zero temperatures during the winter months. A 5W-30 would seem to make more sense. I won't ever track the car.

However....while under warranty it seems prudent for me to use exactly what JLR recommends and that includes using an OEM filter.

 

JLR initially recommended 5W-20, then changed to 0W-20. As my car is stored over the winter, I’ve stuck with 5W-20. Of course, I’ve never remembered to tell the dealer that, so they’ve use 0W-20 when they’ve done it, and I buy 5W-20 when I do it. Oh well.

 

Despite the fact that almost all owners are religious about what weight to put in the supercharged V8s 5.0, I have found that the engine sounded way healthier and quiter with 5W-30 oil. Kinda makes me question JLR's choice of 20 weight oil and is it really for tolerances/clearances or is it for fuel economy?

 

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Just to get the record straight and I owned 2 of them (a 2016 & a 2018) the C7 Z06 Corvettes (650 hp, supercharged engine) after their introduction in 2015, had a valve train issue. Part of the cause of this problem was the engine oil condition after the 500 mile break in procedure. So, after this problem was caught and diagnosed, the GM warranty on the C7 Z06 Corvettes only, was modified to include a free 500 mile oil change to go along with the standard Corvette 2 free oil changes in 2 years or 24,000 miles, both from date of delivery, which ever came first. There's still a lot of belief, especially with higher horsepower cars, that an early, low mileage (say, 500 miles) oil change will extend the engine life of your car. That Z06 problem demanded that early 500 mile change....none of the F types do and neither did the 490 hp standard Corvette engine. Change it early if you want or believe you should, but it's really not necessary, but it's your car so do what you want.