> Since I have to bleed my brake and clutch system (rebuilt brake
> and clutch MC
> and new reservour), and I have no idea what kind of fluid is in
> there now, do I
> go with DOT 3 or 4? What is the difference?
Not much difference between DOT 3 and DOT 4, except DOT 4 doesn't boil until
higher temperatures. You can add DOT 4 even if it there is DOT 3 already in
there. Either one will eat paint, and rots over time, even still in the
can. (Some sources say opened cans should be discarded after as little as 1
month, but I think a year is probably safe as long as the can was resealed.)
My personal suggestion would be to add DOT 5, and ignore all the "doom and
gloom" crowd that say you can't possibly do that. I've done it on several
vehicles, and it works just fine. DOT 5 is more expensive, but will not eat
paint and does not deteriorate over time like DOT 3/4 does.
If your current fluif has been in there so long that you don't know what it
is, I'd suggest bleeding all the old fluid out anyway. DOT 3/4 does rot and
turn dark over time as it absorbs water (and starts rotting your brake
system from the inside out), so it needs to be changed occasionally.
Bleeding once a year until you see clean fluid will do.
There is also an issue that some British brake seals are not compatible with
American DOT 3/4 fluids. So, even if you choose to stay with paint removing
brake fluif, use only Castrol brand. It should be readily available in any
auto parts store. (DOT 5 you'll probably have to mail order ... TRF has a
fairly good price on it.)
YMMV of course
Randall
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