This is my sisters 2000 Suzuki Grand Vitara 2.5L V6 with 46,000km. It's been religiously serviced by the dealer every 10,000km. But since her warranty ran out, she asked me to service it. It has used Shell Helix Ultra 15w50 & 5w40 all its life. I noticed oil leaking from the valve covers. What causes oil leaks? Is it the low quality oil? Or is it the extended oil change? (she sometimes goes 12 months between oil changes). Or do the valve covers just need tightening? Will changing oil to say, Castrol SLX 0w30, stop the oil leak? Or do the gaskets just need changing? Or is this considered normal? Im not really prepared to change the gaskets bcos that would involve removing the intake manifold.
Some pics:
Some pics: