I stick to the book with my 51, 1000 mile grease intervals and 3000 miles for the oil. If you look at the kingpin bushing design, there is very little space for the grease to reside so only a very small amount actually services the joint. Greasing items like U-joints allows a good inspection and a chance to see if they move while under pressure. I use the grease job occasion as an end to end inspection of the chassis.
