MiCk: I oughta mail you my request for an honoraium for looking all this stuff up for your, today!
I don't wanna arm wrestle w/anyone but, DexCool is very good stuff, CF's beater pos excepted, lol! Havoline Brand is titz, too,imo.
Here's DaWord from
"Withidl"...I trust his expertise:
"I was a Lubricant Engineer with Texaco Lubricants Company which owned the Texaco Chemical Company which developed and patented the "ORANGE" coolant which is the OEM fill in ALL General Motors vehicles, ALL Catapiller engines, ALL Cummins diesel engines, etc.
This "ORANGE" coolant is a "paradigm shift" in coolants which GM gave their blessing to by tradmarking the product developed by Texaco Chemical Company as "DEXCOOL" (Texaco's trademark is "Texaco Extended Life Coolant" which will have the "DEXCOOL" trademark on the package).
I have stated the above because I believe, but I'm not absolutely certain since I retired from Texaco 2.5 years ago, that the BMW OEM coolant is probably the same, except with a blue dye instead of the orange dye.
The "Green" coolant uses "disolved solids" to protect the engine's cooling system from corrosion, but these "disolved solids" also attach the water pump seals causing early failure. The Texaco Extended Life Coolant/DEXCOOL uses "organic" chemistry which essentially does not become depleted AND does not attach the water pump seals, which is the primary reason GM uses the product because it allows them to warrant their water pumps for at least 100,000 miles (GM's advertises DEXCOOL's life as 150,000 mile or 5 years, but in Texaco's testing the ORANGE coolant for over 300,000 miles there was essentially no degredation of performance).
Additionally, the "Green" coolant protects the cooling system from corrision by laying down a white INSULATIVE film on the interior surface of the cooling system which inhibits the transfer of heat from the cylinders into the coolant, i.e. the engine runs hotter. The "ORANGE" coolant using "organic" chemistry does NOT lay down any film and thus allows for a MUCH better transfer of heat from the cylinders walls into the coolant, i.e. the engine runs cooler.
Both the old green coolant (with disolved solids) and the new ORANGE coolant (organic chemistry) use ethlyne glycol as a base, so if the green coolant is added to the ORANGE coolant nothing really adverse happens except the the ORANGE coolant has been "dummed down" to the green coolants performance level (eats water pump seals, coats the inside of engine with a white insulative film and must be changed out every 2 years).
Prestone and other coolant manufacturers sell this technology under license from Texaco (now Chevron/Texaco).
In April of 2001 when I took delivery of my X5 4.4i I personally had the BMW dealership change the blue coolant to the ORANGE coolant. I did so only after I got the dealership to confirm that BMW would warrant the engine on the same basis as the blue coolant. BMW would not have done so if their blue and Texaco's ORANGE coolants were not equivalent.
The net, net is that you DO NOT want to add the green coolant to BMW's blue coolant."
BR,md
PS: fwiw, I've been adding the "orange crap" to our X for 4 years...had the "free 2 yr flush and fill" and still add the orange crap to this day. The consumption has reduced slightly over the 4 yrs: I think the pin holes in the cheapazz plastic components are plugging up, 
. Since stlrs are hour away, I don't drop by for a pint of oil and a half pint of coolant and a fooking loaner, lol! I jes'keep adding a 50-50 mix.