Email back from Merc’s EU tech department and it does need uprating! FFS!
Did you actually expect them to say something different? Once again, does it say anything about it in the towing section of the owners handbook?
Maybe they put rubbish cooling fans on them when new to save money. Now if you’d bought an Volvo, Audi, etc you wouldn’t have this issue.
I’d still try towing without the upgrade first – it’s not like you’re daft enought to actually let the car overheat.
Thats not true. I have an xc90 and in the owners manual it states that if you are towing and have the 2.9 petrol then you need to fit an extra oil cooler for the transmission (which is what i expect the merc one is for).
The extra cooling for when towing up long hills and the speed dropped but the engine is working hard, not htat we have many of these types in the uk. My manual also advise using the manual over ride when going down these hills to stop the brakes from over heating.