Originally posted by manny
Regular ( glycol based ) antifreeze, mixed with Dexcool type antifreeze will produce a mixture that looks like something out of a sci-fi movie.
It will clog up any cooling system, not just MB's.
MB antifreeze, Dexcool, and conventional "green" Prestone are ALL ethylene glycol based. The difference is the corrosion inhibitor package - organic for Dexcool and MB, inorganic for the green stuff.
Dexcool has received a bad rap. The rust/scale problems are due to running for extended periods with low coolant levels. I've been using Dexcool in all my cars since 1995 - before it even became available through the normal retail outlets - and have had no cooling system problems. GM has built on the order of 30 million cars/trucks with Dexcool.
Texaco won't support the long life (5 year) change interval in cars that have ever had conventional green coolant. There's no scientific way to test the life properties on cars in service that have a wide range of cooling system condition, so their recommendation to follow the normal cooling system change interval on vehicles not originally equipped with it is conservative.
I continue to observe a two-year change interval, and changing coolant on the 103 engine is simple. If your car does have conventional green antifreeze and you switch back to MB type or Dexcool, be sure to thoroughly flush out the system as there is some incompatibility between the organic and inorganic inhibitor packages.