ramrod This doesn't answer your question but, may help your case. Have you changed the engine breather?
timbo Lube mobile are probably wrong if you have a 6 cylinder. Then it's likely to be leaking from the brake vacuum pump, or excess pressure from the breather box. You need to see someone that knows about volvos
itsabitsa I'd second Lupica in Moorebank - father and son team, their workshop is almost exclusively old Volvos! Not the cheapest around, but good quality work and no BS.