Mixing green & Mercedes coolant?

I just replaced the thermostat in my 1985 turbo diesel wagon. I drained the radiator of green coolant, but not the engine. Then I refilled with Mercedes coolant. Is it okay to mix the 2? Or should I take it to the shop and have them drain, flush and refill with Mercedes coolant?
Thanks

It is not going to ruin a cast iron engine, but it is best to flush. If you have not flushed in the last few years, good idea anyway.

I guess my question is whether I should worry about what was left in there before I refilled the radiator with Mercedes coolant. The stuff I drained was green. We've had the car for about 2 years, no leakage problems or overheating etc. The engine appears to have been well cared for. SHould I worry if I mixed Mercedes coolant with garden-variety green stuff?
thanks.

Kent while we are all on the topic of raditor flushes &c. i would like to add that every old car and, i mean every old car i have ever done a run of the mill radiator flush too, resulted in me buying a new radiator. see the scale and build up actually sealed the radiaiotrs and when i flushed.. i removed all thozse false sealing surfaces. have you found similar results?

also is MB coolant a different color than the garden varity antifreeze? my AF if like a thick green looking stuff in my car.

MB coolant is basically clear. Maybe a little pale yellow if anything, but pretty durn clear. That's what I've been getting from the dealership at least, so I figure it should be the stuff.