This will depend on which engine type you have, or to make this simpler if your vacuum pump is driven by the auxiliary belt then it has sealed for life bearings and does not need any oil adding. If you have the other type of vacuum pump that is driven by the timing chain then the pump is lubricated by the engine oil.
Cheers! I have taken a look and many thanks to you because it appears that the information/advice I was given by an 'expert' mechanic appears now to have been a ploy to gain work!
Happy days - but no work for that lowlife scut!