Packard Forum Index » Post-War (1946-54)

I've searched the forums and read all the manuals, but I can't seem to find any info on the type of brake fluid that is acceptable for use in my '48 Super Eight. Any help would be appreciated!

DOT3 is the currently available fluid that is consistent with what was originally used, and DOT4 (slightly higher boiling point) is also compatible. However, if you don't know what type of fluid is in it now, it would not be wise to "top it off" with anything. This is especially true if at some point it was converted to use silicone-type brake fluid. Rather, you should drain, flush thoroughly (methyl or isopropanol alcohol is a good flush), air-blow dry, and then refill from scratch with new fluid.

While draining and flushing, if you don't know that it's been done recently, it would be a great opportunity to replace hoses and rebuild or at least examine wheel cylinders, steel lines, master, for condition (leakage).

Thanks! That's what I'm going to do. I read somewhere about the silicone based fluid, and from what I understand, it is not compatible with today's brake fluids. Would the silicone fluid affected the rubber components in any way (assuming they are still useable)?

Silicone brake fluid is also not compatible with yesterday's brake fluids either. If you change to or from silicone brake fluid, you'll have to change ALL the rubber components - hoses, wheel cylinder and master cylinder seals, etc., and flush residual fluids from the lines.

G'day Joseph,
to PackardInfo. I invite you to include your '48 Super Eight in the Packard Owner's Registry here on PackardInfo.

Silicon brake fluid also greatly shortens the brake switch life if it is an older manufactured switch.