My 96 Mercedes running hot after about 20 minutes

[Hhill2638]

I'm having trouble with my 96 Mercedes Benz S50p it keeps overheating. The water pump works fine I don't know Mich about these vehicles but every so often it leaks right where the radiates fluid goes in and leaks badly I need some suggestions on what it could be it tales about 20 or so minutes before it starts to heat up weve kept water and antifreeze in it and stop leak to and nothing im hoping its not the head gaskets but ive been told of its low on oil it could male it overheat it not the thermostat ciz it looks brand new it has a brand new water filter in it to the fan runs fine the heat does run a lil hot after the car starts heating up plz any advice would help