My 98 V70 had very loud squealing rear brakes when I bought it, about a year ago. Applying anti-squeal lubricating goop to just about every contact surface did not help at all. Then I discovered that there are little teflon shims that are supposed to be installed behind the brake pads (between the pad and the caliper piston). These shims were missing on my car. Installing these shims solved my squeal problem. The shims are available at Volvo dealers and elsewhere (I got them at swedishpartswholesale.com) for about a dollar each - you need 4 of them.