seems a whole lot cheaper to pick up brake fluid if you buy it in car packaging rather than bike packaging, any reason for this?
cheers.

Same stuff. And yes anything not bike tagged is usually cheaper.

as long as it’s not mineral oil, that is not the same. I was told recently that you use or mix the oils it’ll blow your seals within a week.
(shimano stuff is mineral)

For bikes it’s either DOT 4 or DOT 5.1. Yes, car and bike stuff is the same. You can mix DOT 4 with DOT 5.1 as well without any ill effects.

The DOT 4 has a lower boiling point than DOT 5.1. Unless your off to the alps, DOT 4.1 will suffice. Its in my car and most other family saloons.

No such thing as Dot 4.1, you either want Dot 4 or Dot 5.1. Not ideal to mix but you don’t need to ‘clean’ the system when switching, just make sure you purge all the old fluid out when bleeding in the new.

LHM Fluid is the mineral stuff used in Citroens, don’t know if its compatible with Shimano, heard a rumour Shimano just call it mineral fluid and its actually Dot fluid, but can’t see why they’d want to cause that sort of confusion!

Dot 5 (as opposed to Dot 5.1) is silicone based and is NOT compatible!

heard a rumour Shimano just call it mineral fluid and its actually Dot fluid,

Err, you heard wrong then, as I use LHM in mine.

Well it was a comment posted on here way back 🙂 Have to admit I was doubtful.

“The DOT 4 has a lower boiling point than DOT 5.1”

tosh!

well not quite, dot4 generaly has a lower boiling point than dot5.1, but not always, it’s dependant on the brand.

Shimano stuff isn’t DOT fluid: I’d imagine that what with DOT being as nasty as it is, anyone punting it out without the necessary precautuins (warnings etc) would be in a lot of bother. Plus, get Shimano stuff doesn’t smell like DOT, not does it make your skin go all funny…

Shimano, Mineral, LHM, Audi PS Fluid, OM15 – all the same basically, and compatible.

Dot anything is non-mineral hydraulic oil. Can be mixed, but why would you use 4 if you could use 5.1? (BTW, Dot 4 boils at 155C wet and 230C dry, Dot 5.1 boils at 191C wet, 270C dry – That’s the DOT spec, so if you find a brand of ‘DOT 5.1’ which boils lower, it ain’t 5.1)

Dot stuff is pretty horrible, mineral stuff is much more pleasant. Both types will get past the other one’s seals, so wrong fluid = lots of leaks and new seals all round. Not good.

“The DOT 4 has a lower boiling point than DOT 5.1”
tosh!
dot4 generaly has a lower boiling point than dot5.1, but not always, it’s dependant on the brand.

you are confusing DOT 4 with DOT 4/600 – the later is higher than 5.i always and the former is lower always.
Brands will not alter they are International standards as is oil ratings and octane on fuel etc the rest is hype and marketting.

well not quite, dot4 generaly has a lower boiling point than dot5.1, but not always, it’s dependant on the brand.

No, that’s the point of it being called 4 or 5.1. 4 boils at 230 deg C, 5.1 boils at 270 deg C.
They’re both polyethylene glycol (PEG) based fluids but they have different characteristics and hence different grades.

Gotta love the amount of mis-information on the internet, it always seems more when this subject gets raised. Shimano stuff is completely different and is not compatible with DOT fluids. 4 and 5.1 are miscible (all it does is lower the boiling point to about 250 deg instead of the 270 that 5.1 boils at normally). DOT 5 is a different fluid again (silicone based) and is not compatible with 4, 5.1 or mineral.

noooooooooooooooooooooooooooooooooooooo

The standards set a minimum boiling point in both wet (3.333? water) an dry (new fluid) conditions. So you could create a DOT4 that boil at 300degC.

Yes a cheep (i.e. minimum for the standard) DOT4 will boil at a lower temp than DOT5.1, but not al DOT4’s are created equal.

can you give an example then of a DOT 4 with a higher boiling point than a 5.1 please?
I am not saying you are wrong but I have never come across one.

lifted straight from the PACE website, a DOT4 that boils at 312 degC

lifted straight from the PACE website, a DOT4 that boils at 312 degC

RC312 Racing Disc Brake Fluid – SKF-GRS
Don’t let boiling brakes ruin your run or aching arms spoil your Alpine fun. Re-bleed your tired, faded and fried anchors with PACE’s new premium grade brake fluid and you’ll notice the fingertip difference immediately. Perfect for Freeride fooling, epic mountain riding or adding a new lease of life to old ‘closed’ brake systems. Not compatible with Shimano or Magura brakes. Specification 250ml
Dry boiling point; 312 C. Wet boiling point; 204 C. US FMVSS 116 DOT4/SAE J 1703/SAE J 1704RC10

back to the original post…

The manufacturer will specify the type of fluid. The different types of brake fluid should never be mixed. Using the wrong fluid is likely to cause seals to fail, resulting in brake failure.Automotive fluids are DOT (Department of Transportation) approved and are generally polyglycol fluids. The D.O.T. fluids have different ratings, such as 3 or 4. Contact the manufacturer for a specific recommendation. Automotive brake fluids are caustic and toxic.

taken from the parktools website.. 2nd paragraph

so, back to the original question… was that a yes?

Yes. EXACTLY the same stuff. Just in greater quantities.

And cheaper.