If now is a good time to change over...I have been using dot 5 for almost 20 years with no problems including paint issues when I get messy. NAPA still carries it.  Now let the neysayers loose.

That's what nine out of ten use. Steve (CTR)

Three different stores with little to choose from. I wanted something besides the house brand.

I di not see any DOT 5 which are the ones that seem to cause discussion.

All I could find was Castrol DOT 3/4. The label reads like Castrol GT LMA container I have, but it has a different product number. It says advanced performance series, everything on the label is the same at the GT LMA.

You have to read the labels again after things being the same for 50 years. I have been using the high end German fluid. I use ATE Super Blue for the racers. I recently walked into a auto parts store I have used for years. New Guy, I picked up a qt of fluid and went to check out. The clerk took it and put it back on the shelf and told me I didn't want that. He explained it is ($100 a qt should read $11 a qt.) and is for high end German cars only. If I'd give him the make and model he'd pick something for me. I told him I have a 85 1275 classic mini. He tells me they didn't start making minis till much later. At this point I'm thinking this will never end. So he picks up a bottle of Castrol LMA and hands it to me. I handed it back and told him I was going to buy some brake fluid some other place. I found a good quality Dot 4 and the brakes feel fine. I like to flush the hard pipes before installing new parts. I gravety bleed the whole system. Buy pvc clear tube sized to be a snug fit on bleed nipples. I kept a set of baby food jars with lids punch holes in lid and stick the hose in. It helps if you grease the threads on bleed nipples. If you have different color fluids you can tell when the old is out for the most part. Depending on the job the long under car hard pipe is the only one I'd not change unless required. Steve (CTR)

And do I need to worry about flushing the lines of residual old formulation fluid?

I found this thread from a while back:

//www.minimania.com/msgThread/109311/1/1/Brake_Caliper_Seals

 

So I know this can be as contentious as asking about oil...

But I am redoing hydraulic systems on both cars and I may as well switch brake fluid now. The old Prestone version of DOT 4 I was using has changed formulation and is no longer easy to find. It used to be every where.

So what newer formulation type is suggested?

My search for brake fluid did not turn up any of the old contentious threads...

Terry