You can't go wrong with the owner's manual recommendation on oil. Volvo call for 10W30 for all temperatures between -4F to 104F. Any 'name brand' will do.

Benski is right about the green antifreeze. It will protect against freezing/boiling almost indefinitely, but the anti-corrosion chemicals degrade and it does need to be changed about every 2 yrs.

In my 1983 240 manual seven (7!) grades of oil are shown for various conditions, and 10W40 is one. In my 1985 manual only three are recommended (5W30, 10W30, 15W40 - this latter one for extreme conditions such as high temperature trailer towing). I do recall that GM recommended against 10W40 - I think they stated that the additives required to get that viscosity spread caused piston ring sticking. Maybe today's stuff is better? With the high-temperature capabilities of today's oils, there is no reason to use thicker grades, except for extreme duty conditions. Even then, my 1998 S90 manual says "synthetic 10W30 would be a better choice".

FWIW, I use Mobil-1 synthetic 5W30 in everything but the pressure washer. (Still breaking it in on the factory fill)