My car a 2000 Chevy malibu started over heating and reached 260 degrees and then car randomly shut off.... I Let it cool down put some antifreeze in it and started it back up drove it 15 miles down road and never reached over 140 degrees no lights on... Any thoughts?? Would check engine light come on??? Does it have a fail switch??

You may need a scanner to proceed - - is the cooling fan coming on at 230 degrees and does it cool down the engine to normal (200 degrees) ?

If it doesn't over heat it's very possible that there is just too much coolant, so if it's leaking from the overflow there is no problem as that's what it's designed to do

Are you sure it is oil? I have a 2000 chevy malibu also and something similar happened to be but come to find out the radiator just needed to be flushed out and it was old rusty deposits.

CHECK THE THERMOSTAT. THERMOSTAT IS THE ONE THAT SENSE THE ENGINE TEMPERATURE AND TURNS ON COOLING FAN WHEN THE ENGINE IS HOT.

Did you do the flush and fill yourself? did you put pure antifreeze in with distilled water at a 50/50 ratio? If your antifreeze mixture is pure or almost pure antifreeze, then it will not transfer your heat and will not heat the cab well at all.

The dealer recommend GM Dex Cool Antifreeze.
But there are complaint against this type of coolant.
http://www.stevesnovasite.com/forums/archive/index.php/t-128547.html
In GM cars we replace Dex Cool with Prestone green coolant.
It's up to you. Ask before but if you decide to change the type of coolant then:
If your intention is to add coolant only, then you need:
Mix with
ANY COLOR ANTIFREEZE
ALL MAKES ALL MODELS
of cars and light trucks
add to ANY color antifreeze
PRESTONE
50/50
PREDILUTED ANTIFREEZE/COOLANT
EXTENDED LIFE up to 150000/mile 5 year protection.
DO NOT ADD WATER.

If your intention is to flush the RADIATOR (Cooling System), then you need:
Mix with
ANY COLOR ANTIFREEZE
ALL MAKES ALL MODELS
of cars and light trucks
add to ANY color antifrezze
PRESTONE
EXTENDED LIFE up to 150000/mile 5 year protection.
On the back you have to read directions:
Step 1 Drain. Step 2 Flush. Step 3 Fill.
Recommended to ad 30% to 50% volume, distilled water. If you flush the system and rinse with water you must add only 30% water to the antifreeze. There is more water trapped inside the engine compartment, because the thermostat is closed. Make sure to have a coolant density tester. When you finish one of 5 balls must sink, that indicates that you reached 50/50 strength. That means 50% Prestone and 50% Water, which will provide to your car a -34F degree FREEZE-UP Protection , and +265F degree BOILOVER protection.The next day,with a cooled engine open radiator cap, and test the strength of coolant. If not quite right, then siphon coolant from the radiator and add antifreeze, or distilled water as necessary.
Make sure to disposal the used coolant properly.

This sounds more like the coolant system is low on coolant. Check your radiator, and reservoir for proper level. .

check thermostat, cooling system may be plugged. make sure water pump is working ok.

is electric radiator fan coming on? if not the relay or fuse is bad

you should always put water in a overheated car with the motor running sounds to me like cold water in hot engine syndrome unfortunately this is fatal to the motor most likely cracked heads