quote:Originally posted by george pence:
Jan,
DOT 5 is silicone based and not compatible with any other brake fluid. There is also DOT 5.1 which IS compatible with DOT 3 & DOT 4 brake fluids.
I know of no way to tell them apart.
If you cannot contact the previous owner, or the shop that maintained the vehicle/installed the brakes, the next safest thing to do will be to have the system flushed thoroughly with a power bleeder and refilled with DOT 5.1.
your friend on the DTBB
If all DOT 5 are silocone and not compatible with DOT 4, I wonder if I mixed some DOT 5 & DOT 4 in a small glass if it would seperate out like water & oil? If so, I could try the same with whatever DOT is currently in my system to take a sample and see if it seperates out when mixed with a DOT 4...chem 101 didn't benefit me too much. My shop says they were using DOT 4 but I find it odd the cap says DOT 5 only, so just trying to double check, as who knows what the prior owner did too.