Essentially, only the American Petroleum Institute (API) Service SA motor oils have no additives, and they are therefore incapable of protecting modern engines.
Without many of these, the oil would become contaminated, break down, leak out, or not properly protect engine parts at all operating temperatures.
Some additives permit lubricants to perform better under severe conditions, such as extreme pressures and temperatures and high levels of contamination.
Some mass-market engine oil additives, notably the ones containing PTFE/Teflon (e.g. Slick 50)[17] and chlorinated paraffins (e.g. Dura Lube),[18] caused a major backlash by consumers; the U.S. Federal Trade Commission investigated many mass-marketed engine oil additives in the late 1990s.
These unsubstantiated claims have caused consumers to be lured into adding a bottle of chemicals to their engines which do not lower emissions, improve wear resistance, lower temperatures, improve efficiency, or extend engine life more than the (much cheaper) oil would have.