Does anyone have any strong preferences for engine oil for a V70N T5? Currently I am using Millers 5W40, and am happy with it, but am wondering if anyone has any experiences of other oils. My car runs a 300 bhp BSR ECU upgrade, but is used year-round in the UK on fully synthetic with no problems. Both 0W40 oils (Castrol RS and Mobil 1) have been recommended, but my previous car - a 335bhp Ford Escort RS Cosworth - suffered an unnerving loss of oil pressure when I tried Mobil 1! I do't want to go too far the other way either, with either a 5W50 or a 10W60... Does anyone have any recommendations?

I no longer indulge in any track days, so normal or occasionally spirited road driving is all my cars get now.

Thanks in advance.

Castrol 10/30 or 10/40 is what works the best here in the U.S. And is what is reccomended by Volvo.