I am in the process of restoring my 1979 F150 4x4 and wanted to see if I could use DOT5 brake fluid in my truck instead of DOT3. DOT5 does not absorb water over time and is not corrosive. I have replaced both front calipers, both rear brake drum cylinders, all brake lines, and the master cylinder so none of the brake system components have had any brake fluid in them yet. Can I use DOT5 brake fluid?

 

No reason you can't use DOT5. Even if there was a little DOT3 left in the system, they are miscible. Many have switched existing systems successfully by simply sucking the DOT3 out of the reservoir, filling with DOT5 and bleeding the brakes to get most of the DOT3 out.