Thank you Hristo Tomov, Michael and JDUB. I have changed the o-ring at the base of air cleaner case and the engine cap. Oil leak has continued present at the inferior end of the line coming from the base of the mentioned case to the upper part of the the lower oil pan, where is the check valve. I also have oil leak around the o-ring, it is new. In my ignorance, I think the car has a problem in the Typical Positive Crankcase Ventilation, but I do not know at wich level. I wuould appreciate if some of you can tell me what is the grommets
Thank you

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Juan