[contenderv07]

my X has baout 40,000 miles and I keep hearing good things about the amsoil stuff, would it be ok to switch to this now???

 

[Lonesome Crow]

I switched mine to Mobil One @ 10000 miles and I have had no problems, in fact my mileage went up a little.

 

[willgr1]

anytime is a good time to switch, generally the earlier the better

 

[mike100]

I haven't put more than 90000 miles on any of my cars or trucks since 1992, so... never.

ON EDIT, except for my turbo subaru wrx..it was a selling point that I used mobil one. that and the little boxer motor only drank 3.75 qts every change.