no... no... no need to get in an uproar.
Using 10-40 isn't going to hurt your engine, it?s just not the right oil to use. The higher the number the higher amount of heat your oil can stand. Also the thicker the oil gets. So if your engine doesn't run that hot, don't get such a thick oil. The thinner the oil it is, the better its going to protect your engine at start up.
I would stay away from Casterol Syntec oil, it contains high amounts of ash which will lead to high amounts of deposits. Really good oils are Redline (high amounts of silicon, good stuff for RX7s), Neo (handles high amounts of load, and high change intervals 12-24k), Amsoil (never tried this one, head lots of good things) and the ever so popular Mobil 1 my fav cause its the easiest to find and priced decently...
I use 10w30
