Can I mix blue and green coolant BMW

So I discovered what was making my gearbox have problems after long drives.

Blue/Green crystallized sludge had clogged up my transmission cooler.

Like most BMW's more than three or four years old, someone had emptied the blue BMW coolant and refilled with green coolant.

If you are going to change between the two, be EXTREMELY diligent when flushing and make sure to drain and flush the ENTIRE system. Clearly someone didn't manage to get to all the blue coolant and it's gone bad. I'm just glad I got to it in time before it destroyed my gearbox.

You're not suppose to use green coolant even if its a complete drain and refill

Something to do with eating away the aluminum.

BMW coolant is blue... Not green

Thanks Captain Obvious, but I already caught onto that, hence why I referred to 'blue BMW coolant' and 'green coolant' separately.

Also, it's all well and good to say "you're not supposed to" but how many BMW's have you seen lately with the correct blue coolant. I use the correct blue BMW coolant in my E46 despite it costing more than ten times what high quality green coolant costs, but I can tell you that I will not use it in any of my other cars and I'm not alone in that sentiment.

You need to replace your entire cooling system! NOW!

in b4 Mango, cooling officer!

in b4 Mango, cooling officer!

That's right! I'll be handing out tickets to those who violate the cooling laws! :read:

Genuine BMW coolant: $19

One gallon distilled water: $1

Auto parts store coolant: $14.99

Total additional cost to do it right: $5.01

I've been mixing Blue and Green coolant for the last 13 years and 336,000 miles without issues... Granted I flush my coolant every 60k, but I have never had any blue/green mixing issues. I use whatever I have on hand whenever my coolant is low. Just my two and a half cents worth...

Can do it any way you like. Might get lucky, might not. All I know is it costs an extra $5 to guarantee you're doing it right.

Even if it was true that the brand of coolant didn't matter, the "awesome" factor alone knowing you have 100% factory BMW blue coolant running through the system is worth it. I mean just opening the expansion tank cap and seeing pure blue BMW coolant makes me all giddy inside.

It's just the proper way to do it.

personally, i don't see any coolant when i open the expansion tank, the plastic rod should be at the top of the neck when open

personally, i don't see any coolant when i open the expansion tank, the plastic rod should be at the top of the neck when open

Press the float down with your fingers. If your system is filled with blue, you'll see it.

That's right! I'll be handing out tickets to those who violate the cooling laws! :read:

Genuine BMW coolant: $19

One gallon distilled water: $1

Auto parts store coolant: $14.99

Total additional cost to do it right: $5.01

As you still need the distilled water, its really a savings of only $4.01! The only issue comes when you don't have BMW blue on hand and need it fast - then the cost goes up. That's why I keep a jug on hand.

Luke

As you still need the distilled water, its really a savings of only $4.01! The only issue comes when you don't have BMW blue on hand and need it fast - then the cost goes up. That's why I keep a jug on hand.

Luke

True, but I don't count on people to use distilled water when they're not using the proper coolant to begin with. :thumbsup:

After I did my cooling system, I just took the other half of my jug and filled it up with distilled water. I've got it sitting under my sink. Used to be in my car when my rad was leaking, but I have no need for it there now.

...I use the correct blue BMW coolant in my E46 despite it costing more than ten times what high quality green coolant costs...

Dude, where are you shopping?
You're either being taken for a ride on the BMW coolant or you have found some amazingly cheap place to buy the other stuff.

Full price BMW coolant is $17 from the dealer, $13.50 from Clickable (but out of stock ATM).

Glad you finally found the culprit for your trans problems tho!

Scott

Dude, where are you shopping?
You're either being taken for a ride on the BMW coolant or you have found some amazingly cheap place to buy the other stuff.

Full price BMW coolant is $17 from the dealer, $13.50 from Clickable (but out of stock ATM).

Glad you finally found the culprit for your trans problems tho!

Scott

I get a concentrate to make 10L of Tectaloy Coolant for $7.
The BMW Coolant costs $18 for 3L worth of concentrate.
(and I'm Aussie, I'm allowed to exaggerate a little!)
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Anyway, hate to rain on anyone's parade but the whole reason I noticed the sludge was because I was replacing my entire cooling system. It's already done.

I'm on 110,000 miles. My upper and lower hose were failing. I noticed that someone had replaced the water pump and thermostat, though I did it again. My hoses were original and my expansion tank was original. My transmission thermostat was mangled. My radiator is original and in great condition. That's the only thing I didn't replace.
I also attempted to change to a Z4M cooling fan and found the connectors are totally different. Uhg. *Soldering iron*

Also, Mango, should you add heater hoses to your cooling overhaul? That and a couple other things I can't remember are the only things I didn't find on yours. ALSO, I don't think the bracket should be optional, as I didn't buy one and then found out that coolant runs through it. I thought it was just structural. Oops!

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Funny you guys mention distilled water too. On my other cars I've never bothered using it. I use a hose. I've recently been told that non-distilled water is VERY bad for it, definitely converted me. Will only ever use distilled water again.

How'd you clean the sludge out of the trans cooler?
If the trans cooler was gummed up, are you sure the radiator is really in good shape?

An Aussie exaggerate? Funny, I haven't seen that yet....

That's right! I'll be handing out tickets to those who violate the cooling laws! :read:

Genuine BMW coolant: $19

One gallon distilled water: $1

Auto parts store coolant: $14.99

Total additional cost to do it right: $5.01

I'll pay for my ticket in Mango points. Thank you sir.

That's right! I'll be handing out tickets to those who violate the cooling laws! :read:

Genuine BMW coolant: $19

One gallon distilled water: $1

Auto parts store coolant: $14.99

Total additional cost to do it right: $5.01

Auto parts store coolant is one gallon premixed.
1 gallon of Genuine BMW coolant will make two gallons once mixed. Since you need ~2 gallons anyways...

One gallon Genuine BMW coolant: $19
One gallon distilled water: $1
Total to do it the right way: $20

Auto parts store coolant (x2): $29.98
Total to do it the wrong way: $29.98

Up front savings from doing it the right way: $9.98