500E Coolant Loss

[Fangio]

In late April of this year, I had the coolant system in my 1992 500E flushed. At the end of Sept, my coolant light came on and I added 8 oz of Water Wetter, plus 16 oz of distilled water to fill up the reservoir.

I happened to check the reservoir this past weekend (2 months and maybe 1K miles later) and found it to be low again. This time, I added 32 oz of distilled water to top it off.

My question: should I consider this to be the coolant system "burping" (a total of 56 oz of liquid has been added since late Sept) or am I losing coolant?

I should also add that after I had this coolant flush in April, once the warmer months came along, I noticed my temp gauge going higher than it had in the past and actually had the fans kick on for the first time I can remember.

Any thoughts? Have I added too much H2O and now need to add coolant? What coolant can I use for the M119? Do I need to get it from the dealer or is there other stuff out there that is OK? Do I need to go back to the dealer and get this sorted out?

Kirk
1992 500E
Pearl black/gray
63K miles