Offroad-Express

Can anyone explain to a muppet what one is and what the readouts mean?

Its a test done to an engine an compared with manufacters specs to see if you have worn rings/ worn valve guides or valve guide seals A leak down test while the pistion is at top dead centre is a better test to have done as this shows where the leakage is going

For your safari you need it with 2-3% of manfactures specifications for it to be considered to be in good nick. Mine is for a 20y/o vehicle.
Al