1993 Cadillac DeVille Owner's Manual - Page 266

c A CAUTION: Rust or dirt on the wheel, or onthe parts to which it is fastened, can make thewheel nuts become looseafter a time. The wheel could come off'and cause an accident. When you change a wheel, remove any rust or dirt from the places where the wheel attaches to the vehicte. In a emergency, you could use a cloth or a paper towel to do this; but be sure to use a scraper or wipe brush later, if you need to, to get all the rust'or off. dirt I Remove any rust or dirt from the wheel bolts, mounting surfaces or spare wheel. Place the spare on the wheel mounting surface. I .Never use oil or grease on studs or nuts. If you do, the nuts might come loose. Your wheel could fall off, causing a serious accident.