Coolant - Mixing Different Brands

[2052006 10]

I have various bottles of coolant which I'd like to use up when I refil the cooling system - 6.6 litres according to Haynes.

 

I have some genuine BMW coolant (still sealed) and some genuine Volvo coolant (opened). Both types are the same colour, but the labels don't tell me anything else.

 

Am I right in thinking it should be ok to mix different brands so long as they're the same colour?

 

Is it ok using a bottle that's been opened (about 2.5 years ago)?

[Biggles 65]

As long as it's the same colour, I've never bothered about sticking to the same brand. What you do NOT want to do, is mix blue with red.

 

If in doubt, mix it before putting it in the cooling system.

[allanallen 528 2 Cars]

I remember a thread about coolant on here a while back where 'oilman' (apparent expert) said that colour had no baring on what the coolant was whatsoever.

[Ryan 99]

The colours are just dye added to the coolant to help identify it. By convention glycol-based coolant is blue or blue-green, and organic coolant is pink, orange, or red. But you can't rely on the colours being correct. The bottle should say if it contains glycol or not.

 

Glycol coolants can be mixed with each other. Organic coolant shouldn't be mixed - not with glycol, or with other organic coolants.

[Slo 283 1 Cars]

At work they tell us blue is for steel blocks and pink is for ally blocks and that if we put blue in ally engines it will rot them. Dunno how much truth is in that.

[Biggles 65]

They're all glycol based, it's the additives that are different.

[allanallen 528 2 Cars]

At work they tell us blue is for steel blocks and pink is for ally blocks and that if we put blue in ally engines it will rot them. Dunno how much truth is in that.

That's what I always thought and in general that is true, but as mentioned oilman explained differently and I've since used blue coolant that was recommended for aluminium engines. The stuff I use in my enduro bike (all ally) is luminous green.

[scbond 15 1 Cars]

They're all glycol based, it's the additives that are different.

 

This. Glycol is an organic chemical compound and it goes into all of them. Whether it's different glycols that go into each I'm not too sure, but the difference is just for different operating temperature usually. The UK is very temperate and I've never seen a problem with sticking to the blue kind year round.

 

As for the blue coolant causing rot in alloy engines...sadly you've both been lied to. As you know, they are meant to keep temperatures down and prevent corrosion. There's nothing in either kind to cause rot on either steel or alloy. Alloy is also particularly more resistant to corrosion than steel is, so it would be the other way around if anything. The only thing in the coolant mixture (providing it isn't dodgy, with things like sodium added which would just be stupid) is the water.

[allanallen 528 2 Cars]

Thin aluminium cast blocks rot much more than a iron block.

 

Why is some coolant sold as being suitable for aluminium engines and some isn't? Again, regardless of colour.....

[Anthony 1,003]

I was about to say - anyone that's stripped an XU alloy block and looked around the liner seats will know that alloy blocks certainly do corrode and badly at that!

[mrfirepro 127 1 Cars]

I've got 6 blocks that can testify how bad the corrosion can be..

this was one of the better ones...still useless

 

 

different block, same problem

 

[scbond 15 1 Cars]

I did say alloy is particularly more resistant, not rot-proof. And technically it's the metals, or one in particular, in the alloy that corrodes.