</font><font color="blue" class="small">( cannot find any info on the net for changing the oil )</font>
What kind of information are you looking for? First I'm guessing you mean an "air" compressor, since I never heard of an oil compressor. If it should be how to change the oil, I'd have to see it, but would expect the oil drain plug and fill plug to be obvious to the observer. So, if that should be your question, perhaps you could post a picture or two for us. However, if the question is what oil to put in it, the normal oil for those was 30W non-detergent motor oil. Now, since I'm not sure of the model, I'm guessing there is no dip stick or sight glass to show the oil level, and if I'm right, you want to fill it right to the top of the fill hole.
And welcome to Tractorbynet.