[charshan]

just had second service from Hyundai only 3,147 kms on clock told by them is normal that a vapour of oil comes from oil filler cap due to pressure. anybody heard of the problem

[asathorny]

Nope, never had that on mine.  Dry as bone 

[sundiz]

Does not seem to be normal. Crankcases have ventilation system to get the pressure out. If the ventilation system is blocked then the engine starts pushing the oil out somewhere...

[AlanHo]

Definitely not normal if the filler cap is correctly attached. There is a lot of oil spray and mist in under the engine cover from the valve gear and if you open the filler cap, even slightly when the engine is running, some oil mist will escape. 

I would take it back to the garage and insist they check the crankcase ventilation system

[eye30]

None on mine either

[CraigB]

What I'd do is totally clean the oil off the engine and check it again after a few days/week of driving, if there is new oil film developing around the cap then there could be an issue with the cap seal (dirt trapped around seal or cracked ) or possibly a blocked breather/valve from the rocker cover.