Hey, Scott I got a problem with my car overheating. I got a 2011 Mitsubishi Lancer GTS 2.4L 4B12 engine, a CVT transmission, car has 195075 miles. I bought the car at a dealership it was labeled pre auction. I knew it probably had some issues so made an offer I thought was fair on it and bought it. The dealership sadly didn't know really anything about the car. They didn't even clean it. They didn't have any maintenance sheets on it or anything. So being a mechanic myself by hobby I said I'll take the chance it ran good, sounded good, shifted good both in automatic and using slap shifter, and it even came with a few aftermarket upgrades. But, after about a month it needed usual repairs like a wheel bearing(literally have to replace these everttime I buy a used car, never fails. I keep wheel bearing for all different models on deck now haha), brakes pads, ball joints, pvc valve, transmission Fluid cooler, oil pan gasket, and etc. Well also when I got home with the car the day I bought it I popped the trunk to clean it out (the car was pretty dirty) and i noticed alot of fluids in the trunk bottles empty and full. I got worried. There was oil, trans fluid, power steering fluid, and coolant and a brand new axle. So automatically assumed somethibg was wrong but the car ran fine for months. Even after changing oil pan Gasket my car was losing oil somewhere didn't seem to burning it or leaking it. Well then found out the oil engine cap was bad replaced that thought the problem was fixed. Then still losing oil. So after a few weeks discovered the oil pan plug needed replaced and fixed that and problem was solved. Well,, after that I then had another issue arise. I purchased it in april. Well in June the car out of no where started to overheat. and it's Sept now so this overheating has sadly been an issue for months now going on 4 almost. I first noticed the coolant was low thought I had a leak put the dye in didn't see it anywhere..so I was like ok my first thought is usually thermostat so changed that with a faulty one which I also thought was wrong one bc it didn't look like the original one I took out. But it fit so used it anyways and car still overheating. So I checked my fans and one fan had broken plug so I fixed that n still overheating. Then I changed the water pump which a friend helped me and put some that gasket maker on there bc I didn't have the gasket for the one side of water pump bc really they say not to take it off that way but it much easier to take the whole thing out then  the way the service manual says too. But anyways so so far I changed the thermostat, water pump, and dye checked for leaks, I also didn't pressure test on engine and the exhaust leak on the coolant test to test for head gasket issues, and they all turned out fine no issues apparently with the head gasket then something bad happened like a week ago my car overheated in let it cool down open radiator to water in and it was filled with that yellow mucus type sludge. Obviously my oil had gotten into my radiator but I still don't know how. I went home flushed the radiator for hours to get stuff out noticed the water wasn't running thru the radiator very well like it did last time I did flush. So I tried to unclog it and get oil junk out. It didn't fully unclog I don't think honestly. Bc I put more water into radiator after flushing and have been running the car now for almost a week. It is still overheating but no oil in the water has appeared again. It did that one time and hasn't since. It only overheats when I use my cvt in manual and only when driving and it takes about 3 hours or more of driving before overheating. I use my car for work so 3 hours is not a long time for ny work day which is usually about 8 hours of driving. But it does not overheat in idle and I can even run ac in park n no overheat I drive with ac it overheats almost right away. I turn heater on it goes back to normal and then will stay that way even with heater off for about 15 to 20 mins before starts to overheat again. Now it takes about 3 hours to start overheating after driving but once it starts to overheat even if I let it cool down for 30 mins it will overheat after 15 or 20 mins after that first initial overheat. And I haven't lost any water either so it overheating but still full of water and I just don't know what to do. Would it be the radiator I don't wanna spend all that money ey just to find out that it still overheating. Sorry bout long message or question I just have done alot to this car and I'm getting very upset I wanna fix it but not trying to waste money either or my time.