Here the deal with this. The industry is moving to a low pay model, you are just not going to find the same experience you did 20 years ago. You will never see a counterman who "knows" all the part numbers by memory anymore. Reasons for this are simple A.) except for a few of us , the vast majority are low payed employees B.) cars now have far more parts now with the switch to fuel injection. Honestly do you really expect the average counterperson to know about specific parts on a 70's beetle? Or know that your VW requires 502 oil? This industry especially with the big 3 , are rapidly becoming just another massive retailer. They just happen to sell stuff for cars. The problem is that A.) Mary doesnt know anything about her car , so she falsely believes someone behind the counter knows EVERYTHING about her individual car B.) Ted who gets a real hard on showing off how much he knows about this motor, part etc. So what does he do , treat the person who is probably trying to help him like a common idiot. With the move to lower wages and increasingly becoming extremely retail , the days of finding skilled and knowledgeable counterman is fast disappearing. I still do it because I love it and love to help people. And the skilled counterperson , with the correct certifications can still make a honest wage. On a side note to this rant , I have seen far more just plain stupid customers than just plain stupid counterman. So in short be nice to your parts guy , we are people too. We cant read your mind , we dont have a crystal ball . Most of us just want to do a good job and help our customer out.