Second hand multimeters are an unknown quantity, If you are using it for voltages that can't hurt you go right ahead if you are using it for dangerous voltages then ask how much is your life worth to you.
So, it's what you are telling me is that if my meter reads 479 and the circuit is actually 480 that will make me make a LIFE and DEATH decision?
I would try to explain but it is quite obvious neither of you are electricians so I won't waste my time.
There is no way I would take a brand new fluke 88 and start poking the leads to some high tension wires, but I'm willing to bet the OP isn't either. There is Nothing wrong with using a used meter to check for voltages a car uses, or even household power. He could even be extremely cautious and make sure the previous owner didn't replace the fuses.
Now let's all chill and stop licking 9 volt batteries...
new fuses, battery and OE leads and it'll be good as new.
function check what ya can.... then pronounce it ready to work!!
...and get it calibrated.

Av~ why would it matter if he changed the fuses?
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Yup, and it isn't the voltage that gets you, it's the amps (to an extent).