Think I saw a thread about this on Briskoda?

"Lift up the rear seats, then remove the circular cover. under that is the fuel tank sender, pump housing.

Theres a big locking ring around the top, make sure that is tight and not leaking."

Also

"Does the PD130 have injector leak off pipes?

These return fuel that wasn't injected back to the next one and then down to the fuel cooler and eventually back to the tank.

Common for these to go occasionally on older cars so if it has them get them checked.

Otherwise I'd be checking all your fuel lines, especially those by the fuel filter for leaks and also check your intercooler pipes as they can leak at the joins with the EGR/IC and I would think that would smell quite dervy, although it would be more burn derv than otherwise.

Also have a look under the car to make sure you have not damaged any of the fuel lines on debris."

and
"My Octavia 20 valve was smelling of oil and it went into the dealer 3 times and they said nothing was wrong. I wrote to Skoda and got a free pollen filter but it still smelt. I took it around the corner to the garage that fixes my Triumph Stag and he found a split breather pipe very quickly. Ordered and fitted new one. smell gone. "


Plagiarised to save you signing up (though worth doing) and searching.