What Grade Oil

[Braindead]

OK, once upon a time you just stuck 20w50 in at an oil change and that was that.

Now I have a Prius and the idea is to save fuel. The manual recommends anything from 20W50 thought to 5W30.

The 5W30 and 10W30 have 'energy saver' in the description, or words to that effect.

All the grades are shown as suitable for UK temperature ranges.

What grade oil should I put in the !Removed! thing for optimum protection and economy?

[CarinaII]

i'd go to Halfords and get a tub of their 5W40 fully synthetic.