Too little information here to help. You gotta pin point the leak. Sometimes that may involve winching up your car so you'll need a workshop's help.
Please download the E34 Bentley manual (google for the links) and familiarise yourself with it. Also familiarise yourself with www.realoem.com
to locate the exact parts for your car or to understand its schematics when necessary. Also, please read all of the stickies at the top of these forums.
If you just bought this car, I suggest that you change the fuel pump (and its O ring), fuel pump's relay and crankshaft sensor to new oem ones. These components fail without forewarning on E34s right at this age and you car will not start, which can be very inconvenient and ultimately expensive if you're not highly mechanically inclined to troubleshoot and repair yourself, this is your daily driver, and you do not have a stop-nag button on the missus. And also take a look at your fusible link, located next to your battery. Make sure it looks ok and if suspect, replace with a new one.
Most previous owners (po's) also do not take good care of their cars. As such, I suggest that you change out your water pump (get one with a composite impeller, ignore those with cast iron, stainless steel and plastic impellers), your thermostat, your radiator cap and bleed screw. The first two are the culprits behind the most common overheating issues that we see on bimmerfest, and the last two are just too cheap not to change out. Ensure that both your main radiator hoses are soft to the touch and if hard (due to its age), please change as they could likely burst under pressure. Check if your auxiliary fan runs at both speed settings by jumping the radiator sensor plug according to the bentley manual, which is important as this fan has a secondary cooling function. Also, change out your fuel filter to a new one (not related to overheating but not changed by too many pos, so your filter in there might be 10 years old.)
All of the above do not contain an exhaustive list of no-start and overheating issues. However, they are the most common ones, and if you look through the archives you'll find many threads relating to these. Some forummers think that its an unnecessary expenditure on a car that's roughly worth $3k to do all of the above when the components concerned seem to be working fine right now. Considering how common these issues seem to be, and considering that most E34 owners are not trying to become automotive engineers by learning on-the-job, I recommend that the peace of mind and time efficiency that you'll get by doing it all at one go on your schedule rather than you car's, is well worth paying for. This is especially true if you're not the only one driving this vehicle, it is your daily driver, you intend to keep it for the foreseeable future, and there is no reliable evidence that these replacements were done in the past 3 years. Penny wise has a way of quickly turning into pound foolish. Stay ahead of the curve.
Oil leaks are not uncommon on all cars of this age, and sometimes the simpler thing to do is to top up on occasion and just keep on driving if the leak is not bad, its not in an important area, and/or the cost of mechanical repair is exorbitant. Some oil leaks in the engine can be minimised by using thicker oil, which would help your compression for most high mileage vehicles as they assist in sealing the piston rings which would be rather worn by now. Of course, to make such a judgement call, you'll have to know exactly what's the leak and project its effects down the line.