I mixed antifreez when coolant was low only about 2 quarts and after maybe 100 miles iot stared over heating should i empty all the coolant out and put orignal back ?

Generally the ratio of antifreeze to water depends on the severity of the cold that your car is likely to encounter. A ratio of of one part antifreeze to two parts water should suffice for most cases. The antifreeze should be added premixed with the water: just adding neat antifreeze to the engine first and then adding water will result most of the antifreeze settling to the bottom of the engine and taking a very long time to mix. That all said I think your overheating issue is not to do with the antifreeze itself. Are you loosing coolant? Check that the coolant filler cap is on tightly and that its seal is in good condition. Most coolant systems become pressurised when hot. If the cap is not on securely pressure cannot build up and overheating can occur. Also check that no air pockets are trapped in the system. Put the heating on inside the car to full and squeeze the top radiator hose occasionally as the car warms up. Incidentally, this putting on the internal heater to full can be a good emergency step to take if stuck in traffic and the engine starts to boil. If you are not loosing coolant but the car overheats this is a sign that maybe the thermostat is not opening when it should and perhaps ought to be replaced. If your car is very hot/overheated switch it off and check the radiator bottom hose, careful it should be too hot to touch. If it is just mildly warm then this is another bit of evidence that thermostat is faulty. A further check is to remove the thermostat. Fill a clear jug with boiling water from the kettle and lower the thermostat into it. It should pop open but after a few minutes pop closed again even though the water will still be very hot. Most thermostats open in the 84 to 87 degree centigrade range. If your thermostat fails to do anything then it needs to be replaced. If the bottom hose is hot then water is circulating and the thermostat is most likely working. Check that the radiator fan is running. If your car is fitted with an electric fan these are triggered to work by a thermostatic switch. If it fails to come on then either the fan motor is dead or the switch is not working. The switch can be checked easily by testing for electrical continuity when it is hot. If the fan is activated by a thermal clutch and it fails to engage when hot then it is the clutch that has failed.

Why was your coolant low? did you inspect engine for any leaks? two quarts is quite a bit low. when you start the car up do you see big white vapor cloud along with water? say no please! good because you probably know what that means. Whenever you lose coolant and you cant explain why.... that's not good. Its always good to see a leak except from a cracked block. A head gasket you wont see any leak from the engine. Check the dip stick or oil filler cap, does it look watery? or like a milkshake? no i hope! Now let engine cool approx three hours.. recheck and top off coolant, replace radiator cap if it looks rusty or corroded, then warm up engine and put your hand on the upper radiator hose, you shouldn't feel any coolant running though the hose in fact you should be able to squeeze it flat. Now when the temp gauge gets to around normal operating temperature the hose should feel hot and when you try and squeeze it you should feel a slight back pressure...this is all good, thermostat is working and water pump is supplying pressure. If the hose is not hot after it warms up, you have a stuck thermostat and will need a new one. a bad thermostat will cause the engine to prematurely boil off coolant and that may be why your car was 2 quarts low.

When you use just water it keeps the boiling point at 212 degrees with a proper mix 50/50 it'll bring boiling point up to approx 240 degrees. did you check also to see if your fan was on? if the fan isn't working you'll overheat a little bit but on a hot summer day in stop and go traffic you'll boil over. did your car boil over? was the reservoir overfollowing with coolant? if it was then maybe your fan is inop or the fan relay isnt working. Whenever you're driving your car and it starts to overheat, turn your heater on full blast, this will take the cooler water out of the heater core system, which is usually cooler, and it will dump it into the engine..it might be enough to get you to a service station and let the car cool down and reservice the radiator and try and find a leak.
Im telling you all this because im trying to save my daughters car right now because she didnt think a low coolant warning light was no big deal. I took radiator cap off and it was half empty, i topped it off , i didnt feel any water going through the upper hose either..pulled out thermostat, it was toasted shut, replaced it, filled up radiator,..no leaks anywhere. You would think that a car with 297000k would have a little leak somewhere..but after driving 10 miles the low coolant light would start to flicker and it lost about half a pint. i checked exhaust and it had a lot of moisture and a little vapor cloud...prefromed a "block check" and it confirmed the blue test dye turned yellow...bad news. blown head gasket. Well two weeks now and a bottle of "Blue Devil" $65 head gasket sealer and so far so good. The first week it still ran a little rough but after you get up to speed the water would get blown off the spark plug and run like brand new. Now im in the second week of periodic checking and so far the levels arent dropping anymore and theres only a slight roughness when you first start it in the mornings but clears up in a couple of minutes. also the tranny fluid was two pints low probably due to overheating also. She said that she hasnt seen the low coolant light come back on so maybe this stuff does work! Im still checking.
i bought the car new 2.8L V-6 GTU installed a 40hp performance chip in it and always performed routine maintenance. I wanted to get at least 300000k out of it..will see. i know i went on a bit here but i just want to emphazise the importance of the cooling systems in cars.
hope this was informative, any feedback would be appreciated..its what keeps us going at Fix Ya!