Matt,
You absolutely NEED case lubricant when full-length sizing those .45-70 cases! As far as I know, carbide sizing dies are not available for this caliber because of the length and case taper. They would be prohibitively expensive to manufacture and sell. Carbide dies are nominally available only in straight wall pistol calibers (.38/.357, .44 spl/magnum, .45 colt/.454 Casull, etc.) They are identified by the soldered-in carbide ring at the case mouth.
Just any lubricant will not be suitable for case sizing. Engine oil, grease, etc lack the film strength needed for this high-pressure application. Any of the commercial brands will do fine: Imperial sizing wax, RCBS, Lee, Lyman, etc. Even ONE trip into the sizing die without lubricant is enough to badly score the die walls. You might need to polish it out using 600 grit wet-or-dry sandpaper wrapped around a 3/8" wood dowel. Clean using solvent, and relubricate heavily before sizing that first case.
Luckily you can remove the decapping stem from the F.L. sizing die and use a punch to drive out the case.
You can get away without using case lubricant on the .38/.357 because it is a relatively short, straight, untapered case, and the frictional forces (especially with carbide dies) is much less.
HTH
John