Shooters Choice FP-10 Lubricant Elite (4 oz)$9.50
FP-10 has been my go-to lube for necking up cases and neck turning mandrel lube for many, many years. Lubricity and viscosity are perfect for neck turning work, and it handles the heat generated when turning with steel mandrels very well. Comes in a 4 ounce flip cap bottle. FP-10 is also an excellent general purpose firearms lubricant. I squirt a little in a bottle cap and apply it to the neck turning mandrel with a flat toothpick. Lube the inside of case necks with a small bore mop, or swab. Remove the lube before loading the cases by soaking in acetone for a bit then dry them on a paper towel. A bottle lasts a long, long time, use sparingly.