Whats so special about BMW coolant??

[Unregistered]

In the US, BMW coolant is Valvoline Zerex G48:

https://www.valvoline-technology.com...x?OpenFrameSet

[G-man]

How about the G-05 is that OK to use?...it seems no one has the G48 in my area since the G-05 came out.

[bill g]

There is a coolant available here in Australia called Nulon Long Life which I found has very similar specs to BMW coolant, at about half the price. The stuff is green colour.

[George M]

Bottom line is....compare G-05 specs to G-48 a.k.a. BMW blue coolant. I like the specs of the Mercedes approved G-05 better than the G-48 and it is half as expensive and much more available. Why I run the G-05 in my big six.
George

[Bellicose Right Winger]

70/30 is very good for cooling performance, since the coolant has poor heat transfer properties relative to water. The downside is it prevents you from getting a full dose of corrosion inhibitors. Settling for a partial dose of corrosion inhibitors seems to contradict conventional wisdom which says use ONLY BMW coolant to minimize corrosion problems.

Paul Shovestul

Actualy... do 70 water/ 30 coolant

[MicahO]

The other downside is reduced freeze protection, though 70/30 is probably enough for at least 360 days per year in 90% of the US......

[MicahO]

Adding coolant to water does increase the boiling point, and therefore decrease the danger of boil-over.

However, water does have a better capacity to transfer heat than does coolant. So as a straight cooling fluid in a system that does NOT EXCEED the boiling point of that system, water alone is superior to a water/coolant mix. Because of this, many race engines that do not need to worry about the lifespan of the system components will run just water or mix with Water-Wetter. But those guys can toss their water pumps after a day or a weekend, so they don't need the other protective measures found in coolants.

Well, if you look at any coolant jug, it says otherwise... You will notice that if you put more antifreeze, antifreeze/coolant would withstand higher temp. It says on the jug. If very cold or very hot, use 70 coolant / 30 water for optimal performance. Cars operate in a wide variety of temperatures, from well below freezing to well over 100 F (38 C). So whatever fluid is used to cool the engine has to have a very low freezing point, a high boiling point, and it has to have the capacity to hold a lot of heat. The fluid that most cars use is a mixture of water and ethylene glycol (C2H6O2), also known as antifreeze. By adding ethylene glycol to water, the boiling and freezing points are IMPROVED SIGNIFICANTLY! The temperature of the coolant can sometimes reach 250 to 275 F (121 to 135 C). Even with ethylene glycol added, these temperatures would boil the coolant, so something additional must be done to raise its boiling point. The cooling system uses pressure to further raise the boiling point of the coolant. Just as the boiling temperature of water is higher in a pressure cooker, the boiling temperature of coolant is higher if you pressurize the system. Most cars have a pressure limit of 14 to 15 pounds per square inch (psi), which raises the boiling point another 45 F (25 C) so the coolant can withstand the high temperatures. Don't you think 70 coolant / 30 water is a better way to go? I would NEVER run straight water. Also, you need to use only distilled water and not tap water. Tap water containes too much minerals and bad for the system.

[Tiger]

Yes... Water is the main heat transfer agent. Coolant is a modifier and additive. You do have to make sure that ratio is enough for your coldest day. Now, some of you say with more coolant, your boiling temperature is boosted to higher point like 275 degree... WELL if your coolant ever get that high, your engine is kaput! Our thermostat opens at 190 degree...

I had 50/50 in my car... it never overheats in BMW... but on MB, temperature always seem higher than normal... once I dilute it lower, the car run more normal temp. The car runs cooler with higher water content because of it's ability to shed heat better than coolant itself.

Then you say corrosion protection is lower with more water... yes... but not by that much especially if you do change you coolant every 2 years...

[George M]

agree with Paul...will take the corrosion protection of 50/50 to the added cooling benefit of 30/70 any day of the week...but I don't live near the equator either.
George

[Bill R.]

bullhead city driving at highway speeds. I always use the stock bmw coolant since its not that pricey and i always use it at 50/50 concentration. Corrosion protection is my big concern and the raised boiling point. And Tiger motors will survice 275 just fine if they are using a synthetic oil that will continue lubricating just fine at higher temps. 250 temps are fairly normal on newer cars here and they run just fine at that temp. Straight water does have the greatest capacity for heat transfer but thats not an issue since the cooling system is already sized for a 50/50 glycol antifreeze and easily handles the heat load if everything else is in shape. And the typical racing motor actually has lower operating temps than the motor in a street car since the race car usually has a large oil cooler, radiator sized accordingly, a lower temp thermostat, no ac or few belt driven acc. to increase heat load on the cooling system and a richer fuel mixture since they don't have to run lean for emissions purposes. Street engine frequently work under harsher conditions including neglect..
So i'd use bmw coolant 50/50 just like the engineers designed it for.

agree with Paul...will take the corrosion protection of 50/50 to the added cooling benefit of 30/70 any day of the week...but I don't live near the equator either.
George