| Author |
Message |
    
K. March (Apexdisco)
| | Posted on Sunday, August 04, 2002 - 08:36 pm: | 
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What's the differences between the two types of brake fluid?
My disco asks for DOT4. |
PerroneFord
| | Posted on Sunday, August 04, 2002 - 08:51 pm: |
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Dot 3 is an older lower specification, in general it boils at a lower temperature making it less suitable for use in high-performance situations or heavy truck situations. There are a couple of notable exceptions, but just use the DOT 4 if you can find it.
-P |
SG
| | Posted on Sunday, August 04, 2002 - 08:58 pm: |
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The difference is in the specific chemical properties of each, like boiling point, specific gravity, etc.
Back in the 'old days' of Rover ownership (like 30 years ago), and continuing up until the late 1980's or so, Rover brake components were made of natural rubber compounds. Castrol/Girling 'Crimson' and later 'LMA' were glycol-based (as in vegetable) compared to petroleum-based compounds used in other brake fluids. Obviously, you had to avoid the petroleum ones, as many owners learned to their chagrin when seals disolved a week later. Castrol LMA was originally DoT 3, now it is DoT 4.
Even the Brits stopped using natural rubber a decade or two ago, so seal deterioration is not nearly the problem as it used to be. Boiling point is much more important today.
While Castrol LMA is still glycol-based, it has been 'upgraded' to DoT 4. Dunno why/how.... The one problem is that it is hygroscopic and will suck moisture out of the atmosphere...which your brake cylinder walls will not like. If you use Castrol, siphon out the master each year and replace with new from an unopened bottle.
Cheers |
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