So as you can probably see I work for A large atou parts chain. I have been lurking on this board for over a year and find it very usefull for giving all the oil recomendations I recieve questions about. Well today Ignoramous was standing in front of me while I was standing at my highly polished shrine(the oil diplay wich I take great pride in} and said hey dude can I ask you a question? I thought here we go, took a deep breath and said sure. He said do you have any oil that will make my car quit Knocking? I just looked at him until he said( i didn't change my oil for 13,000 miles in my 2002 mazda protege and now It Knocks. I reply smart move. He says ya it has never caused a problem before this time, I humor myself and ask what kind of oil it was? he replied walmart oil change bu this time he took it to tires plus and they recomended Lucas so he added TWO bottles! I live in nebraska were it is currently 5 degrees out I told him I really dont Know anything about oil I just started working here (7yrs ago) and to go ask someone at the counter. we all got to listen to the abuse story before telling him a replacement engine was going to cost 3200.00 and the original only had 44,000 miles what a shame. this how about 50% of the public care for their car. could buy alot of oil for $3200.00!