Checking brake fluid and clutch fluid for moisture
 

The question that is common and nagging is not knowing if the brake and clutch fluid still good. There are several ways to test it including a conductivity tester or even using a voltmeter. I bought one of those conductivity testers on eBay for about $7 delivered and it seems to work pretty well. My bottle of dry brake fluid tested below 1% water. The brake master cylinder reservoir tested below 2%. When water gets to 3% or above, it's time for a fluid change because water lowers the boiling point of the fluid not to mention system corrosion. When I tested the clutch master cylinder it was above 4% or off the scale of this device. I went ahead and changed the fluid by drawing what was in the reservoir out with a syringe and a short thin hose. I refilled the reservoir and did the bleeding using a one-man bleeding check valve and hose to flush out was in the line out the slave cylinder. I've had good results with Valvoline DOT 3 – 4 synthetic brake fluid. The dry boiling point is 480° which is better than average for a DOT 4 fluid. Mark III Supras were made in the era of DOT 3 brake fluid but this DOT 3 – 4 works fine. Ideally, brake and clutch fluid should be changed every 3 years. Here is a link to an interesting article about brake fluids and also a link to the eBay seller of these testers. One strange thing is that the plastic it's made of has a chemical odor.

https://www.speedwaymotors.com/the-t...ications/28676

https://www.ebay.com/sch/i.html?_fro...rt=nc&LH_BIN=1