as a substitute to oil u can apply or take away some reputation points.
in the bar above every post there is a reputation icon. a click on it will show a dropdown where you can approve/disapprove a post which will increase/decrease poster's reputation. you can also add a comment which the poster can see.
in top-right of every post reputation is mentioned. also, in forum home top reputations are showed.
you can give reputation points to other members.
give positive reputations to others for doing positive things like posting important info, behaving well or doing any kind of good stuff etc. etc.
you can also give negative reputations. negative reputarions may be given for showing disapproval to negative works like behaving badly, posting off-topic or controversial stuffs etc.
you have to give reputation to 9 other different persons before you can repu the same person again.
update: now you can view last 10 reputation comments left for you in your user cp.