Hi Gary,
You can use either DOT 3 or DOT 5, depending on what you want to
accomplish.
I'm surprised, however, that DOT 4 isn't available. The stuff is about
as common as dirt, and you are likely to find it in the grocery market
and the 7-11. Many fluids today are marked as 3/4. Presumably that gives
you the price of the DOT3 and the high boil of the DOT4, or maybe it's
the high price of DOT4 and the low(er) boil of DOT 3. Unless you are a
truly sporting driver, 3 will work OK.
DOT 5 is the silicone fluid. I like the product. Others think it's the
pits. Rinse out the old fluid by bleeding thoroughly with plenty of DOT 5
if you make the change. Some recommend that you disassemble all the parts
and rinse them clean. DOT5 does "creep" more than 3 or 4. If you suspect
that you have a weepy cylinder, DOT5 will flow right out. I rebuilt my
system with all new slave cylinder parts when I made the switch about 15
years ago. Having rebuilt the MC about 10 years earlier, I left it alone.
Already the MC is beginning to weep DOT5, after only 25 years. Rebuild
kit--$16, not a big deal to me.
I like DOT5 because it doesn't eat into your eyeballs when it spatters,
nor into your paint. Whether it does or doesn't absorb water is, to me,
not really important, since water will get in anyway, and will rinse out
when you change fluid every few years or so. One is not supposed to find
that necessary with silicone fluid. Having seen slave cylinders with pits
at the bottom (bleeder screw is at the top) I think water settles at the
low point. Haven't run any controlled tests, though.
On Mon, 06 Oct 1997 17:06:40 -0400 G Graham
<ggraham@edcen.ehhs.cmich.edu> writes:
>I can't seem to find DOT 4 brake fluid in my area. Can I use DOT 5 if
>I
>replace all of the fluid in the lines? (have to bleed the whole system
>anyway)
>
>
>
>Thanks
>
>Gary
>74 1/4 MGB
>
>
|