I don't know the definitive answer on this, but I know that some people advocate against using DOT 5 in an older car because it can attack the rubber in the system, causing seals to deteriorate more quickly. I have heard that if you thoroughly flush & clean the system, or have just installed new lines, etc., it's all right. A quick google search will give you all sorts of data on both sides of this issue. In my opinion, DOT 4 is sufficient for the average car under average conditions. At least, I have never had a problem with it. Mark M > From: "Stevan Miner" <miner@xxxxxxxxxxx> > Date: 2004/05/11 Tue PM 07:20:03 EDT > To: <mailing-list@xxxxxxxxxxxxxxxx> > Subject: Re: IML: Silicone brake fluid > > Hi Chris, > I use silicone brake fluid in all of my collector cars for several reasons. > It isn't corrosive to paint, doesn't absorb water and is alot easier to work > with than conventional brake fluid. I've never had any problems with it. > Steve Miner > Miner Auto Service > Winnebago, MN 56098