True if they do it wrongly. I have done it few times and seem ok.

approximately how much the cost to change timing belt/v belt and water pump and all the ancillaries ?

correct.wanna save fuel go buy Honda with L engine.500km ++ sap sap sui.

I replace my valve gasket cover then use 0W-20 on campro ,hahaha guess what not so much on fuel saving but the engine feel lighter coz low viscosity.

anyway back to 5W-30 right now.

Campro 1.6 iafm sweet spot is at 90km/h.if u drove at this speed constantly it can reach more than 6 Liters / 100 km @ 16.66km/l but of coz in 100% highway.

100% city driving with traffic jam 320-340km per tank.