Another brake fluid question.
I've been reading lots of threads on here about Dot 4 synthetic and Dot 4 non synthetic. Whats the difference?
I go in to my local store and can I find Dot 4 non synthetic.........No!
I ask and am told that Dot 4 is Dot 4, and if it says that Dot 4 is what it says on the cap then Dot 4 it is.
I contacted an oil/fluid supplier (UK) and spoke to their Techi and he said that Dot 4 will absorb moisture and that if anything will absorb more than non Dot 4, which is why it is recommended it gets changed yearly. He also said that not all synthetic based fluids contain silicone, which is where Dot 5 comes in, also Dot 5.1 doesn't contain silicone which is why it is compatible with Dot 3 & 4??????? He also said there would be no problem using it in my 2002 K1200RS (Castrol Dot 4 Synthetic as it happens) as this is what it says in the manual and on the lid of the reservoir.
I asked a BMW (UK based dealership) and they told me that BMW do their own Dot 4. I asked is it synthetic or mineral based, he said he would go and look on the can......He came back and said that it doesn't say, only that it is Dot 4, and comes in 250ml tins. He then said not to use synthetic and suggested I go to Halfords and get some from there. I wish I had never bothered.
So I get back to the oil/fluid company that I get my other oils from and tell them this tale of woe and suggest Castrol (of the top of my head) pause, Reply Castrol Dot 4 is synthetic,,,,,,I'll just check,,,,,,,,Yes it is. Oh!
So, what is the correct Brake fluid, Dot 4 or something else?