Is 'It works 5 minutes' correct?

I suppose it's not completely incorrect, but it sounds wrong. Works for five minutes is the preferred option, as far as I am concerned.

But I'm a Brit, so maybe an American would disagree, but hey, they always do.

I agree with you - American always disagree.

Seriously, the phrase: is more acceptable. However, the other way is spoken often enough in casual conversation but it makes some people wrinkle their noses a little.

Thanks for your reply And btw, I use the British style in writing

But that's bad news for me, because now I have to change like 1000 lines of text...

Surely Birdie you're joking

If you're correcting multiple lines of text where only a few particular phrases need replacing, text editors such as MS Word (or even simpler ones) will allow you to type in the specific phrase and auto-replace the phrase or phrases. This saves a lot searching and doing unnecessary tedious labor.

Thanks for the tip but it's not in a text editor, and I've already dealt with that