Castrol also do a 0w40.. But..
It’s important to note that not all oils are DPF compatible. Oils which are height in additives ( to protect the engine) may produce too much ash, the metallic ash builds up in the DPF and causes early failure. So thats something to consider if you’re going off piste with the oil recommendation.
Watching the LR Time video on the disco engine its interesting to note that he says that the 30 grade oils are on the thin side and are chosen to meet emissions regs. I am not sure if this is due to increased viscosity causing increased fuel consumption, which it could. But also increased viscosity causes increased oil consumption (burning) which could lead to DPF damage… Based on the video a 40 grade oil sounds better, especially with all the heavy towing I’ll be doing, but I don’t want to bugger the DPF…