Firstfives.org

Hello everyone!

Because our cars use cast iron blocks, I'm curious what types of coolant everyone runs, and if anyone has issues with their coolant.

I have an RV that uses a 5.9l Cummins cast iron block, and Cummins recommends the following coolant:

https://www.cumminsfiltration.com/organicacidtechnology

Obviously, organic acid technology (OAT) is newer than E12 production, but is a chemistry specifically formulated for cast iron diesel blocks. I'm seriously considering using this in lieu of the BMW coolant for my rebuild.

What say you all?

Mike

I'm not too fussy with brands but I change my fluids fairly regularly. I use Prestone concentrate and mix in distilled water after hosing out the block and radiator. If you haven't done it, definitely remove the drain hole underneath the exhaust manifold because that will fill with sludge.
Anyway I change the coolant out once a year or so and the insides are always coated and clean, and it stays cool even on very hot days. Besides, my current engine has some minor internal damage and is going to be replaced eventually, so I'm not being fastidious.
I was going to add Redline water wetter if needed, but my car never overheats so haven't.
Was also considering ordering some of this because it sounds fairly good: http://www.norosion.com

I've been running the Prestone long-life orange formula since around 1999. It's also an OAT or HOAT forumulation.
I've been very happy with it and basically run it in all my vehicles. Engine was rebuilt in that span too and everything looked
pretty good on the inside. Since it's free of silicates, you don't get all the crusty white deposit material either. I think the Prestone long-life is also especially nice on aluminum surfaces - rather than the white crusty deposits, the aluminum facing the coolant ends up looking smooth and dark grey and free of any noticeable scale.

Robert, Lock,

Thank you both for your suggestions. It seems that Prestone is a strong contender.

Mike

I would very highly recommend G05 HOAT coolant. It protects iron but more important protects copper and solder. Some of the new OAT coolants like Dexcool and all the other similar OAT coolants protect iron and aluminum great but can be hard on copper and solder. Our E12s have copper and soldered radiators and heater cores (unless you switched to aluminum parts). I believe the blue BMW/Volvo G48 is also perfectly fine but contains some 2EHA which I try to avoid in my old cars. Not sure how the new Prestone with Corguard (OAT + phospates) will work in an old system. The old fashion green IAT coolant would also work fine in our cars.

You should jump over to Bob is the oil guy and search the coolant forum for coolants with compatibility to solder and copper. I have been using G05 or G48 in all my old BMWs for years.

Walt B.
'80 528i
'82 320i
'95 318ti

waltb wrote: ↑Sun Dec 29, 2019 3:16 pm I believe the blue BMW/Volvo G48 is also perfectly fine but contains some 2EHA which I try to avoid in my old cars.

waltb - I use BMW OE coolant in my E12. What is 2EHA and why avoid it in older cars?

Thanks, Cory

Oh 2-EHA or 2-ethylhexanoic Acid is a plasticizer. So it softens and degrades some plastics and rubbers. It is a good, inexpensive, and long lived anti-corrosion agent which is why it is used in many modern long life OAT (organic acid technology) coolants (however the Japanese do not use it). 2-EHA works great if the engine was designed with gaskets and metals that are compatible. Unfortunately 2-EHA itself apparently does not protect solder at all. BMW (and others) solved the solder issue by using multiple anti-corrosion agents in their blue G48 formula. G48 is essentially G-05 with some 2-EHA added and nitrites removed. (Nitrite additives are important for certain diesel engines but don't really matter being in there for normal gas engine coolant). If you are interested you can Google G48 versus G05 to find out the exact differences.

For old cars I personally try not to use coolant that has 2-EHA since I don't know if the old gaskets, plastics, and seals will be ok with it or not. I think BMW maybe back specs G-48 so it is probably be fine. I know of people in this group that have used Dexcool and other similar all makes and all models coolants that use mainly 2-EHA in their E12s and E28s and they seem ok. I just use the G-05 which is still a long life hybrid organic acid based coolant but definitely protects copper and solder without any gasket or plastic incompatibilities.

Just my opinion.

Walt B.
'80 528i
'82 320i
'95 318ti

I was researching the abbreviations and found this useful coolant color chart, to tell what you already have

https://www.valvoline.com/our-products/ ... ne-coolant

Loc, waltb, cory58, Robert, Thank you!!

All good points to consider with our cast iron engines. I should also mention that "Eleanor" had reddish-colored coolant when I bought her last year. While she appeared to have uncorroded coolant channels in the head and block, when I pulled the freeze plugs, I could see the extent of scale that had formed (see "Eleanor" rebuild thread on this forum for details).

Mike

Thank you waltb! Great info.

I was just searching around the same topic and found this post on the FCP blog very informative:

https://blog.fcpeuro.com/how-to-pick-th ... r-your-car

I’ve been running Zerex G-05 (HOAT) in my 944 and plan to do the same in the Bimmer.

Sharky1980 wrote: ↑Mon Apr 27, 2020 12:22 am I was just searching around the same topic and found this post on the FCP blog very informative:

https://blog.fcpeuro.com/how-to-pick-th ... r-your-car

I’ve been running Zerex G-05 (HOAT) in my 944 and plan to do the same in the Bimmer.

Sharky,

This is a great find! Thank you for sharing, and kudos to Michael Delikat, the author of this blog. This helps to "barney-style" the understanding of the various coolant options and their advantages/disadvantages.

And it appears that, at the end of the day, you cannot go wrong with BMW blue (HOAT) in our bimmers.

Mike

Ive always used BMW blue, I don't really know if its better but I've heard some people say its overly expensive. Last I looked it was $2 more a 4 litre jug than the stuff walmart was selling.