Tried using automotive grease on a hub rebuild and it turned into a sticky mess a week later

Last summer I was rebuilding the rear hub on my old touring bike and ran out of proper bearing grease. I figured hey, grease is grease right? Grabbed a tub of red automotive stuff from the garage. Worked fine for about 50 miles then the hub started dragging something awful. Pulled it apart and the grease had basically turned into a globby paste. Had to scrub everything with degreaser and start over with proper marine grade stuff. Took me like 3 hours to fix my own bad call. Anyone else ever made a dumb substitution that backfired like this?

3 comments

3 Comments

oscar_hunt611mo ago

Funny enough, the real issue nobody's bringing up is that automotive grease often has molybdenum disulfide or graphite in it. Those are solid lubricants meant for heavy sliding loads, not rolling bearings. In a bike hub, those solids can actually ball up and create little gritty lumps that wreck your seals from the inside. Red CV joint grease is especially bad for that. I found out the hard way when I used it on a bottom bracket and the seals started weeping black sludge after a month. Marine grease is actually a solid choice for hubs since it handles moisture and doesn't separate as easily, but really anything labeled NLGI #2 without solid additives would have saved you that 3 hour nightmare.

felix_coleman871mo ago

Wait, are you sure "marine grade" grease is what you really needed there? Marine grease is designed more for water resistance on boats, not necessarily for high speed bicycle bearings. You probably would have been better off with a dedicated bicycle bearing grease or even a lithium based multipurpose grease. The issue with that automotive grease was likely the wrong consistency and additives. Most car greases use different thickeners and extreme pressure additives that don't hold up well to the light loads and high rpm of a bicycle hub. They can actually thicken up or separate under those conditions. For what it's worth, I've had luck just using a quality NLGI #2 lithium grease from the auto parts store on my bike hubs, but you have to check the label. Some of that red stuff is meant for CV joints and gets stringy when hot, totally wrong for bearings. Three hours of cleanup sounds about right for that mistake. I learned a similar lesson trying to use chain lube on a sewing machine once. Live and learn, I guess.

elizabetht561mo ago

Are you really comparing bike grease chemistry to rocket science here @felix_coleman87? I just wanted to lube up some bearings, not launch a spacecraft.