Originally Posted by Snowy_Astra
I always run 10W 40 semi, its much better at high constant revs (constant 140mph) i found fully synthetic to thin out like water and loose a lot of its lubricating properties (dab of oil between fingers and rub, felt more like glue)
Kind of strange way of thinking. I can assure you WRC cars are constantly high reved and they run fully synthetic. E.g. works Impreza WRC runs Motul 300V Chrono 10W40
http://www.motul.com/motulbaseuk/gab_fiche2.asp