It is the engine rear seal if it is oil or the tranny front seal if it is trans fluid. Tseals are about 15 for the crank and 12 for the tranny. The work is the rand r of the tranny to get to them.
If it is not bad you can live with it. My tranny leaks about a 1/2 apint in 10000 miles not worth doing the seal yet. You can try a seal sweller it will tide you over for a while but evetually you (and I) will have to do the seal.
2005 320 CDI
2006.5 VW Jetta TDI
1991 560SEL (179000 Sold)
1972 280SEL 4.5 ('The Lead Sled' 320000 miles when sold.)
1972 220D (225000 when sold)