Sticking this in the general thread as I guess it is applicable to all cars.
What do you guys think of oil/fluid additives? I'm not a big fan but have used Extralube ZX1 in the past.
It claims it can be used in all oils as well as the cooling system. It did see to cure a water pump squeal but that could just have been wishful thinking.

So has anyone else used it, or anything similar?