Been there T shirt and all that.
Andrew,s tip is a good one.
They may have a used bit.
Trouble is they all go like that eventually
Cos the only real remedy, well not a remedy really more a preventavive.
Do this when You get sorted.
I inspect the end caps regularly.
Any bit of the white corrosioney bits I wipe off .
If possible I change the end cap seals every season.
If the seals are changed and a bit of vaseline applied the end caps and body of the oil cooler will last twice as long.
This applies to the Heat Exchanger too.
Taint just Volvos either.
Had the same experience with Fords and similar.
Make sure Your Eng and G box andodes are in good nick too.