Originally Posted by sdime
I used to own a old Benz and service it myself whenever possible. I wanted to add some grease to the wheel bearing one time, but stopped when I read in the workshop manual that using generic wheel bearing grease will destroy the wheel bearing because such grease is not compatible with Benz's factory packed grease. The manual went on to say mixing factory grease with generic grease might cause a chemical reaction that turns the combo grease into liquid that leaks out.
I just pulled apart the head set on my bike and noticed the bearings might do well with a little more grease. Can I use regular bearing grease from Autozone and just add it into whatever grease is on the bearing already? I have to ask to be sure after the enlightening experience thanks to Benz's technical writer.
It's a bicycle headset, not the high-heat environment of a motor vehicle front axle. As already noted, simply clean out the old grease with a solvent or just a rag if you want, until everything is shiny clean... then use a grease of your choice. I might even consider petroleum jelly if that's all I had. But just about any clean grease you have in the workshop will work. After all, you could probably use the most viscous soap grease you can find in the headset and still not notice the difference -- especially if it's on an everyday utility bike. Just don't go overboard in applying -- a good smear on the cups, races and the balls is all you need.
And a thought if it is a utility bike that you aren't concerned about offending the OCP crowd... cut a piece of MTB inner tube and slip it over the bottom of the headtube before you refit the fork, then lap the inner tube over the bearing to stop dirt and water from working its way in. The rubber won't last a lifetime, but probably long enough before you decide to service the headset again.