Dear Tom and Ray:

We own a 91 and 92 Mercury Grand Marquis. In both of the owner's manuals, it says that the cars should only be greased every 30,000 miles. I'm used to greasing my car every 3,000-4,000 miles. Is there any harm in greasing it every 3000-4000 miles with my grease gun?
Bob

RAY: I wouldn't, Bob. This is a case where more is actually not better. Newer cars have grease seals that are air and water tight. So if the seal stays intact, the grease should technically stay in there forever. And in fact, if you put too much grease in there, you may even rupture the seal.

TOM: Older cars didn't have tight seals. They just had what were essentially "dust covers," which allowed the grease to leak out, and worse, allowed dirt and water to get in. Those needed to be greased all the time not only to replace the old grease, but also to push those contaminants out.

RAY: So you can get rid of that grease gun, Bob. You have no use for it any more. The only people who need grease guns are folks who drive old, rusty, broken-down heaps like...hey! Send that grease gun to my brother!