oil leaks

[Kevin]

If you think about the reality of the situation; You've got a pressurised liquid coming out into a high speed stream of air, so most of it isn't going to hit the airframe, and what does is likely to be evenly spread, so I'd suggest that the airbrush tool is going to give you the most realistic effect.

However, I suspect that isn't going to give you the "artistic impression" that you're probably looking for