Have the mazda6 2.5 , 2007 , manual. A European version.
The dealer changed the oil to 5w-40 but someone was mentioning 5w-30 ( or 20 ) should be used and also I have a US manual that seems to point to 5w-20 .... I guess I can trust the dealer, any opinions ?
I will say no more than 5w-30! Heavy weight oil can lower mpg an cause build up in the engine an crank case, an wear out the oil pumps an feeding system. If its a 4 cyclinder i would put 5w-20, but never go over 5w-30 on these cars itll drop ur mpg by 5-10 possibly more.
