If the oil is nice and clean and appears around the bell housing you have a gearbox leak. Probably the input shaft seal (Pain in the ass to fix)
If it’s a bit dirty and appears around the bell housing then it’s probably a distributor seal.
If it appears on the sump then it’s probably the cam cover gasket (the sump gasket is often blamed but isn't generally the cause)
Problem is when a car is driving around the air blows the oil all over the place (I had a gearbox leak and had oil all over the petrol tank!). It’s best if you give the whole engine bay a good clean using engine degreaser, and then take it for a gentle drive. Once you have had your drive hopefully the source of the oil leak will be obvious.
What kind of engine is in your car? If it’s a fire then it’s probably the cam cover gasket or one of seals on the distributor. Or it could be the driveshaft boots.
Another point, has the leak started suddenly? and how bad is it? If it’s sudden and bad then something has probably fallen off? Check the sump plug and oil filter to see if they are tight.
