how do you use the coolent tester like the one in the link ??

http://cgi.ebay.co.uk/ws/eBayISAPI....018&ih=022&ih=012&ih=024&ih=005&ih=017&ih=022

Take the Radiator filler cap off.

dip the end of the device into the fluid squeeze the teat and release allow it to fill the tube part way then read the scale on the floating hydrometer (generally the graduation level with the meniscus http://en.wikipedia.org/wiki/Meniscus ) is the antifreeze protection level..

read the instructions some can be used with only cold fluid others can be used with both hot and cool coolant...