Coolant issue: perhaps undue paranoia.

Having recently acquired a pristine low mileage 450 SEL, I had a local tech flush and refill the cooling system. Under the advice of a knowledgeable neighbor, I went down to the local MB delaer parts dept., and first purchsed a gallon of MB brand coolant. You know, specially formulated for the aluminum head engines.

Well, when my tech did the flush and refill, he afterwards advised that the coolant provided wasn't enough, so he topped-off the remainder using other coolant in the right mixture of coolant and water, etc.

I'm not overheating or anything. I'm in South Florida (90 degree temps), and my gauge usually at cruise is a bit above the 80 mark, and under stop and go going towards the top of the "8" or I guess 90 area.

My paranoia is: will the use of some non-MB coolant cause a head gasket leak or blow-out? Engine has 59K miles. Just want to avoid problems with a good and tight engine.

Please advise. Thanks.