Found this after seeing another thread for Castrol Edge by batezy_1984
Unfortunately, that oil isn't suitable for my car so did a search and found this (which I was about to go and buy at Halfords for £29.99!)
Castrol Magnatec protects your engine from the moment you turn the key thanks to the way its Intelligent Molecules cling and bond to critical engine parts. Castrol Magnatec protects against engine wear... before, during and after your journey.
At the start of your journey
Up to 75% of engine wear occurs while your engine warms up. But Castrol Magnatec’s Intelligent Molecules cling to your engine, even when it is off, always protecting and dramatically reducing* engine wear during this critical period.
During your journey
Castrol Magnatec’s Intelligent Molecules continue to cling to your engine after your engine warms up. Castrol Magnatec helps maintain top engine performance by protecting your engine in all driving conditions and at all temperatures.
After your journey
All engine oils will drain to the bottom of your sump when your engine is off but Castrol Magnatec’s Intelligent Molecules keep clinging to critical parts of your engine ready to protect when you start your next journey.
Extensive testing has shown that Castrol Magnatec outperforms API SM industry standards and basic API SM oil. In fact, after running Castrol Magnatec for 100 hours, its Intelligent Molecules offer a stronger layer of protection during warm-up and beyond.
Even if you haven’t been using Castrol Magnatec, it’s worth making the change. Castrol Magnatec’s Intelligent Molecules start working for you the day you change your oil. They cling and bond to engine surfaces, significantly reducing further engine wear and damage to already worn parts.
* As tested in the industry Sequence IVA Wear test.