Bullet lube. People make their own, they try and discard various mixes, they buy it from guys who make it up in a shed in the woods. Here's a list of ingredients that people use for bullet lube along with a very detailed analysis of what lube does and how it works. Does the lube have a positive or negative effect on accuracy? Not that I can tell, but I am a casual shooter. How much testing do I have the time and money to do? If I get good accuracy with the bullet and powder combination, the lube on the bullet has one job. It's there to prevent leading. One side consideration is that it not make the gun so dirty I can't get through a day at the range.
Some old lube came my way recently. I haven't used any of it, but the next time I cast and lube, I may to load up a tube of the Lyman. It's not a decision to take lightly, as anyone that uses a Lubrisizer can attest.