Extended Oil Changes & it's Effects on Crankcase Ventilation (PCV)
An overdue oil change will cause premature wear leading to oil burning, high hydrocarbon emmisions (HC), and eventually a blown engine!
Oil changes are much cheaper than engines. Another problem related to neglected oil changes that Volvos are especially susceptible to is fouling of the crankcase ventilation system. As oil wears out, it looses the resistance to forming sludge and solids. This builds up in the crankcase ventilation system and commonly plugs up the flame trap filter and associated components like hoses and separator boxes. Once these parts become clogged, the engine will produce dangerously high crankcase pressure. This forces oil out of the engine seals and in some cases even blows the seals out of their seats and can cause the engine oil dipstick tube to pop out allowing oil to blow all over the engine compartment.