1991 BMW 735 Coolant recommendation

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Hello,

Looking for a coolant recommendation for 1991 BMW 735. Has cast iron block and aluminium head. Last time I used Peak long life, but am told these universal coolants have only 2% corrosion inhibitors, and dedicated formula has 5% inhibitors. Have Prestone dex-cool in the stash. Any thoughts?
 
Zerex G48, avaliable 50\50 premixed at Walmart. If you need concentrate, head over to the local BMW or Mercedes dealer and ask for a gallon of blue coolant.

Alternatively, you can use PEAK OE Equipment European Blue 50\50 with a softer acid than most other blue blends but that's not a big deal in this car.
 
Probably don't have the owner's manual? Get it from the BMW dealer.
 
I use BMW coolant only- and I change it every two years. That regimen has served me well for 37 years and 12 BMWs.
 
G-48 or G-05. They are about the same with the exception of G-05 NOT having 2-EHA which IMO is a good thing in old systems. I personally ran G-05 in my 1991 318i for most of my 116k miles of ownership (bought used). The entire system minus the profile gasket was original, clean, and worked perfect.
 
Originally Posted by JHZR2
G-48 or G-05. They are about the same with the exception of G-05 NOT having 2-EHA which IMO is a good thing in old systems. I personally ran G-05 in my 1991 318i for most of my 116k miles of ownership (bought used).

PEAK makes a G11/G48 blend with sodium benzoate instead of 2-EHA. Main upside to this route is that you get to keep the delicious dark blue color.
 
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Officially BMW would tell you to run BMW blue (aka G48) which does have 2-EHA. So if BMW is telling you to use their coolant with 2-EHA I wouldn't worry about picking a coolant that doesn't have it. Many BMW owners run Prestone without issues which until very recently was a straight Dexclone so you can make your own conclusion.
 
BMW Blue (G48) is what I call G-05 Lite, they are very similar, but the G-05 has a few extra adds like Nitrite to protect Diesel engine liners from cavitation corrosion. Adds BMW blue for a gas engine doesn't require, but it's not a problem being there.

G-48 is gas only I believe
G-50 is gas and diesel rated

I consider them fairly interchangeable in a gas/petrol engine. I would happily run G-05 in your older BMW, but I would miss the great blue colour.
 
The modern BMW G48 contains 2-Eha, which the original coolant would not have had, so i'd probably run G-05 in it.
It has about half the silicate of G48 , 200-300ppm while G48 has 500-600ppm, but Nitrite which is good for cast iron and cavitation protection, Also Molybdate which is a rare inhibitor but one that works really well for many metals specially solder.
 
Originally Posted by Gebo
Probably don't have the owner's manual? Get it from the BMW dealer.


I bought the car new, so yes I have the owners manual, but that information is 29 years old.

Sounds like G-05 is what I want. Thanks to all who replied, I learned a lot...
 
G-05 is a great choice, and readily available in the US.

However, if you want to retain that inky blue colour, there is Pentofrost NF, which is basically a VW G11 Spec coolant ( very similar to G48, but without 2-Eha )
 
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I have a 1980 528i and an 1982 320. I have been using G-05 in them for years. I have also used the older BMW blue antifreeze in the past (not sure it was G48 back then). Before that I used plain old green IAT antifreeze. The G05 has worked fine for me for probably 20 years, I would recommend it.

wb
 
Originally Posted by Bluestream
Originally Posted by Gebo
Probably don't have the owner's manual? Get it from the BMW dealer.


I bought the car new, so yes I have the owners manual, but that information is 29 years old.

Sounds like G-05 is what I want. Thanks to all who replied, I learned a lot...


I don't recall that the manual for my 91 BMW cited a spec, standard, or type. As I recall, it just said genuine BMW coolant...
 
"With the protection of the environment in mind, BMW has been filling all of its vehicles with nitrite- and amino-free anti-freezing and anti-corrosive agents since mid-1986 as standard practice. The use of anti-freezing and anti-corrosive agents that contain nitrites and amines is no longer permissible."

Basically the reason why most German OEMs used G11 instead of G05.
 
Originally Posted by 2EHA
"With the protection of the environment in mind, BMW has been filling all of its vehicles with nitrite- and amino-free anti-freezing and anti-corrosive agents since mid-1986 as standard practice. The use of anti-freezing and anti-corrosive agents that contain nitrites and amines is no longer permissible."

Basically the reason why most German OEMs used G11 instead of G05.


Daimler used G-05 until pretty recently, at least for older vehicles... I have MB-labeled G-05 still on my shelf.

Of course Daimler is not BMW. BMW has indeed used blue for a very long time - whether G11 or G48 a decade or more ago I couldnt say. When I looked into it for my M42, it was G-48, but my BMW was 20 years old at that point...
 
Nitrite- and amino-free, with protection for aluminum radiators was what the manual called for at the time.

The factory coolant turned blue around 1998. Prior to that, it was a pale green, like Volvo's.

G-05 has been a popular alternative to G48, and more readily available in the aftermarket. The Zerex-branded G48 improved upon its availability, but the full strength version is harder to find than the 50/50. NAPA and the parts houses will have the concentrate, but most chain stores will only carry the 50/50 if they have it at all.
 
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