My car is e30 m40 b16 autoHi, i'm wondering if any sifus here can help me rectify with my problem. My problem is at higway speeds with revs above 4000rpm, my temperature gauge rises from 1/2 to 3/4 mark and it stays there if i maintain the revs above 4000rpm. Could my radiator be clogged or could i have a minor leak in head gasket? Normal drive my temperature is a minute below 1/2 because i'm using 80deg thermostat. I dont think my temp. sensor is the problem because at exiting toll my high speed fan turns on indicating that my water is hot. Cruising at 110-120km/h will drop my temp back to 1/2 way mark but takes quite some time also.Another thing is that, my auto transmission oil spluttered out from the dip stick area messing my engine with transmission fluid, could it be overfilled? Just changed the transmission fluid last month.