Mercedes Coolant mixed Prestone
 

My wife was driving the 300e last week when I was out of town. The low coolant light came on. She had the smarts to add antifreeze, but she did not know there was any difference between the MB coolant and Prestone.

She added about 1" of Prestone to the reservoir.

Will this mess up the the coolant? Should I drain it and replace with MB coolant, or not worry about it?

Bill

The bigger issue would be to look into what caused the coolant tank to become low. There is really no reason for it to leak out. Make you have a hose with a pinhole in it, or the hose clamps need tightening. For now Id find out why, then I'd think about flushing the cooling system while your at it with MB coolant. The thing is Mercedes coolant is made for mercedes and it has a low acidity. Acidic coolant ruins engines.

1 inch of coolant in the reservoir hardly seems enough to trigger the coolant light. the sensor in the reservoir is known to be quirky. mine acted up this summer and i merly cleaned it and greased it with silicone grease. i don't think it's urgent to flush and refill your coolant but as omegabenz says i would look into why it was low in the first place.