OK sorry guys had to throw this one in here, on soem late models it will make a differance in not using MB coolant. I know a tech who had a ML causing a temp problem after water pump replaced he worked for the MB dealer. They cked everything replaced clusters ,harness' ect spent alot of time in it tryin to fix inaccurate reading of temp. Well the factory rep was sittin there lookin at this car and he said ( hey why is the coolant green?) they changed the coolant and it fixed the problem with gauge readings. Now thats not sayin its the coolant in your car that is your problem, but I prefer the benz stuff. I have put the green stuff in and never had any problems on the older ones. Just go with your gut , mine would say pop a thermostate in that dude and flush that system and fill with benz coolant.