Check coolant level!
 

I've filled up my reservoir twice now in a month. I've taken it to an indy and he can't see anything leaking and there is not anything in the oil so far. Anyone else had this problem. Thanks!

If I had to guess, I'd say one of your hoses is leaking under pressure.

Ordinarily you find that by pressure testing the system, but with the way the MB reservoir is constructed, I don't know who makes the special cap needed. Has anyone ever pressure tested one of these? If so how?

Buy a new coolant reservoir cap first. It may be as simple as that. Also check your rubber hoses for small leaks , it could be leaking and burning off the engine before it hits the ground to puddle

If that doesnt work then have your radiator pressure tested at a radiator repair shop, there could be a small hole coolant can seep from the hole and down on the radiator coils. Then it would evaporate leaving no visible sign of leakage.

Otherwise check your exaust for excessive amounts of steam coming out, if there is and the car is running hot you probably have a blown head gasket that is allowing your coolant to evaporate through it.

Worst case scenario is that you have a cracked engine block or head, first pray that it isnt them check your oil oil filler cap for white foamy stuff. If you find some relax it still may be just a blown gasket but most of the time its a cracked block or head.

Good luck I hope that its one of the cheaper solutions.

He said there is no sign of leaking in the oil and if the car isnt pouring smoke from the tail pipe its not a head gasket. your biggest fear is the antifreeze is leaking into the transmission. Antifreeze is certain death for a trans. The only thing here is its less than 1% thats the problem. I would guess that either its running hot and going out through the pressure release or you have a tiny leak on a hose that only leaks when the car is shut off hot and pressure builds. this happens sometimes leaving cold weather and going to hot the heat can mess with the hose clamp.

I suggested that he check the oil filler cap because although you are supposed to see signs of coolant mixing with oil by pulling the dipstick and looking at the bottom (which most prople who dont know tend to do), sometimes it will only appear on the cap. I am sure that your mechanic checked most of these things but he obviously missed something (unless he is stalling you out to exacerbate the problem to make more $$$ off you). You should take it to another mechanic and get a second opinion. Just make sure that you dont sit on the problem. Any way you slice it if left uchecked seemingly small coolant issues can end up costing you big $$$.