Slick 50 contains PTFE which is (I am told) another name for Teflon which is also used on pots and pans. It's these particles which can plug up the passages. QuakerState and Penzoil use as a base oil from Pennsylvania, which contains paraffin. They both at one time listed the paraffin on the side of the bottle. My dad use to use QuakerState until he had an engine failure. This was back in the early 80's and QuakerState was also sued and paid out a lot of money for damages. Many people will swear by and at all of these new oil additives. I have used DuraLube in my 94 Dodge Dakota along with synthetic oil. I had a complete cylinder leak down check done when I bought it with 6,000 miles on it and again at 106,000 and all of the cylinders were within 1psi of the 6,000 mile test and I get 23.5 to 24 mpg. By the way I try to change the oil every 3,000 miles but that doesn't always happen, I do have a few 4,000 and two 5,000 mile changes in there and I have yet to add any oil between them. I think it's safe to say that some engines will react well to these additives and others wont, why I don't know but your story is not the only one I have heard or experienced with friends. It all comes down to three things, how well the engine was taken care of over time what oil was used and how often it was changed. After my fathers experience and my own with QuakerState and Penzoil you couldn't give a bottle of either one, personally I'd rather walk than use them, but that's me. Also keep in mind buyer beware, by that I mean be careful about what you hear in regards to these additives, many of these companies are being sued right now over wild claims. I am only relating my experience. Ask other people you know AND trust to see what if any of these they have used and make an informed decision about whether you want to use these additives or not. Dave U. 81Imp 94 Dakota 02 Stratus (wife's) -----Original Message----- From: mailing-list-owner@xxxxxxxxxxxxxxxx [mailto:mailing-list-owner@xxxxxxxxxxxxxxxx]On Behalf Of d_barker@xxxxxxxx Sent: Tuesday, June 03, 2003 9:14 PM To: mailing-list@xxxxxxxxxxxxxxxx Subject: RE: IML: An oily question I put in Slick50 the first oilchange I did on the 67 2 years ago and almost immediately developed a knock. I changed oil again and went back to the QuakerState 10-40 that my father-in-law used for 30 years and noise went away. One of my workmates later told me that Slick50 has lawsuits against it for ruined engines. Apparently it contains parrafin and had a propensity for clogging things in some cases. Dave 67 Haze Green sedan Covington, Wa.