I used CLP and Mobil One 5W30 synthetic exclusively for a long time, until I actually got a -10 for a few of my milsurps, and saw that there are parts (particularly in my M1a and M-1 Carbine) that specifically require grease, and it makes sense, depending on the speed and temp at which that part will be used.
Comparing an auto pistol to a car for operating conditions only applies if you heat your pistol up to 200 degrees and 3500 rpms routinely.