I've started buying microfiltered milk (am in the UK) because I've always had trouble with milk going off before I can use it all when buying ordinary pasteuris

I've started buying microfiltered milk (am in the UK) because I've always had trouble with milk going off before I can use it all when buying ordinary pasteurised milk, but the microfiltered milk stays fresh plenty long enough to use it all up. On the bottle the stuff I buy say it's good for 7 days in the fridge after opening. Experience so far bears this out, whereas normal milk manages about 4 for me. It's entirely possible my fridge sucks, but I have checked the temperature and the milk comes out of the fridge at about 2C, so...