Which coolant for Speed Triple?

Which coolant do I have to use to top up my Speed Triple. I rang Fowlers where I bought the bike and asked if I had to use the Triumph-specific HD4X Hybrid OAT or whether I could use other OAT coolant from Halfords. No they said, it has to be the Triumph stuff. So rang 3X motorcycles, my local Triumph dealer and asked if they had any in stock. We don't keep it, they said we've been using Plutoline for years and never had any trouble.
So who's right, Fowlers or 3X?

 

I've since been told that the issue is likely to be warranty. Mixing coolants is a bad idea apparently since some types won't mix and circulation problems can result (so I'm told). The bike is still under warranty and Fowlers set their bikes up with Triumph coolant which needs to be maintained to validate the warranty. So I guess I'd better carry on using it.