IMHO...most of the engine leaks comes from worn out oil seals, cheap lang oil seals but changing it is quite a challenge for the not mechanically inclined individuals. A gasket would leak if you overheated your engine or you're fond of having an engine wash with a hot engine., gasket especially the original one doesn't just leaks normally.. common answer lang ng mga mechanics na kapag low viscosity rating ang ginamit magleak daw sa engine gaskets...well unless you change by at least 30 from the original specs then it would probably leak. I've used 0W-30 from an orig oil specs or 10W-40 never had a leak on my gaskets..Recently just changed one my engines front crankshaft seals..not because of engine oil na manipis but due to old age..due for replacement. Seals gets hard and will lose its elasticity.