Buy a tester mate. Only a few quid and you will no you have the correct ammount in the car.
If you just wanna no if its got some in although you wont be able to tell how much do one of the following.
Look at it - Its normally got some colour in it.
Smell it - Smells sweet
Feel it - it has ads lubricant to water you can feel the difference
Taste it - It tastes sweet (not advisable as it will kill you but at least you no your car will be ok )
