Bro Its better to change the oil and filter both from company, for atleast 30K kms, and also service... As you know that new car needs more care for atleast 20 to 30K kms in this region. And you already have Elantra, which will create too much problem in future if not taken care well... I hope that you will understand my point...
Also tell me that how many free service maintenance is provided to you by company?? As per my knowledge the free service is upto 5000km, in which they will only charge from you the parts, oils etc charges (this is the case with Toyota)...