I greased the truck after our last two trips and about 4,000 miles. My observation is that the boots were all pretty empty and each zerk took about three pumps to see the boots expand a bit. I'm thinking greasing every 5,000 miles sure won't hurt anything.
It took me all of about 5 minutes to grease the truck and no swearing
It took me all of about 5 minutes to grease the truck and no swearing