2000 mi oci is a good starting place, unless its a common practice on 14'S to run 50 wt, id be leary... whats you book say ? I do track days and mixed street cruising/ back road scratching and 1,200mi is when i start thinking about the oil if ive been very hard on it. it all depends on the abuse ive put it through durring the oci, for a inline four i prefer
Amsoil
mobil 1 4t
motul 4t
all 40 wt's andi know there's plenty of other good ones, i just have experience with these.
if its been a mostly street, some back road scratching oci.. 2000-2500 is the most i like to go (but some of my backroad antics are somewhat compareable to trackdays.. so the normal max
is 2000mi.
i HAVE blown a inline four on honda gn4 40wt.. im a pretty firm believer in higher quality oil now..