thinner grease for wheel bearings a hypothetical

[RoadRaceJosh]

This really is grasping at straws. As others have said, big trucks run their wheel bearings in oil and they have sight glasses on the hubs. The heavy truck folks changed from grease to oil as a way to extend maintenance intervals, not for fuel economy.

Some of the people on Ecomodder.com can get awfully obtuse, but modifying driving habits and cars for increased efficiency is a better (less resource consuming) hobby than most. If the goal really is resource conservation then avoiding one 10 mile trip is probably more effective than running oil instead of grease in the rear wheel bearings of a Corolla for 100k miles.

I would install and use a block heater or clean out the garage and park indoors long before changing wheel bearing lube.

 

[Bassnjunky]

IMO, I would have a hard time believing drag/resistance from wheel brg grease causes loss of fuel efficiency, doesn't grease separate? Currently my boat trailer has oil bath brg's. I do believe oil bath brg's will extend the useful life of the brg vs. greased brg's. Grease retains particulate, oil bath will wash the rollers although it may somewhat polish the rollers if particulate enters the cavity. I currently use SAE 50w racing formula. It is much easier to drain and replace than grease. Only downside is if you happen to develop a seal leak while traveling but I keep spare seals with me at all times.