What is your oil change interval? 5k? 10k?

HX7 is semi-synthetic. Maybe the Castrol you used was fully synthetic. Any big brand name fully synthetic in the right viscosity will do fine in your car for <10,000km oil change intervals. Just buy the cheapest one from Tesco. Big brand name means Mobil, Shell, Castrol. Not Sumo or some niche racing brand.

Mobil 1 is definitely a good all rounder engine oil. But for your oil change interval, you can make do with any brand name fully synthetic. Save money.

Shell Helix Ultra or Total Quartz fully synthetic, both from Tesco, whichever cheaper. Tesco don't sell fake engine oils, despite what people say.