I personally do not sequo a constant line depends on the conditions of guide the type of machine etc etc ....let's say that in principle, if not exceed the 10,000 miles per year, the board of sotituirlo the same even why? the oil undergoes the thermal shock...then to the top of the' c'? there are so many usually prefer the castrol from 10/40 5/40 5/30 ? 0/30.