Even the pros are up in the air. https://www.machinerylubrication.com/...t-storage-life

It's the good old USA. Gotta have the latest, greatest toy. Most don't understand the physics, but if it comes with a snazzy label like new, and 100% synthetic, then it must worth 3x the price.

Sorry if I came on a bit strong in my wording.

I wouldn't personally add grease without removing the old stuff other than something that has grease-zerts on it for that purpose. Adding grease on top of old grease in a non-sealed open system like that of a bicycle hub/bearings seems just like forcing the contaminations on the outside of the grease further into the system. Grease zerts are so designed so that it pushes the old grease out as the new grease is forced behind a closed cavity and then through the bearing -refreshing the grease while pushing the old stuff out and away. Pushing it in sounds like a bad idea to me.

Speaking of grease-zerts, bearing buddies are the best thing that were ever invented for boat and utility trailers though. I've raced and ridden dirt bikes my whole life and know a thing or two about trailers and keeping bearings going. When it comes to boats they are a life-saver. Boat trailer bearings live in a very harsh environment getting dunked/submerged in yucky shallow water often. This is probably much worse than most bicycles get treated.

It's funny how there is nothing like oil/grease discussions to bring out a lot of opinions and discussion. Everyone has their own nostrum patent snake oil it seems they favor or are pushing. It doesn't matter to me that much other than following manufacturer's spec as far as using the correct type for each application.

Like you said, a lot of the high-end greases are so proprietary that they are like Col. Sander's 11 herbs and spices. They won't tell the secret but that probably has more to do with people finding out it's just ordinary grease with some special sunshine pumped up through it from the backside.

Grease is (almost universally) an oil mixed with a soap (the chemical definition of soap, not a bar of Dove). Wax isn't part of the equation (although some waxes can be saponified into soaps).

"Best if eaten by xx/xx/xxxx"

Two places I do this, one is new assembly, where I don't think the factory uses adequate lubrication. (Saving half a cent on grease per hub adds up if you make a million of them, and you don't worry about warranty returns.) The other are things that it's not worth the effort of fully disassembling, like cup-and-cone bottom brackets. It's not worth taking the fixed cup out to inspect it, and you're not going to get all the grease out of the shell unless you use an unreasonable amount of solvents.
Zerk. With a K. Named after its inventor, Oscar Zerk. He also invented the hubcap.

Synthetic marine grade grease is all you need for any bicycle bearing and any conditions.

Lubes well in all temperatures and resists washout.

Thank you. I hate it when is misspell things or use words incorrectly. I appreciate being corrected so I don't continue to make a stupid error.

Second that! The "tackiness" property of the marine grease makes it work exceptionally well in bike-bearings where there isn't a seal or compartment to keep the grease in the wear-tracks. I've taken apart plenty of BBs where the balls have pushed the grease aside soon after installation. The grease on the sides is perfectly good, but it's not doing any good because it's not between the balls and the races. The stickiness of the marine grease pulls it back into the joint very well.

It only takes a very thin film of grease (not visible with the naked eye) on the BBs to provide adequate lubrication. If there is insufficient lubrication from day one with conventional wheel bearing grease, then we would see scoring of the BBs and races within the first 1K miles. I've used green and generic wheel bearing grease. Can't say one is better than the other after multiple 5K mile overhauls.

A car engine will run fine with 20W-50 or 0W-20. However, thinner 0W-20 gets to critical components faster, and has lower sliding friction at normal operating temperature. This is the main reason why many auto mfrs are specifying 0W-20 oil to squeeze out an extra 1-1.5mpg on the EPA fuel mileage test loop.

Best grease I've come across is Krazy Grease. I've had the same jar for five years and have used in on my bearings only once. I also used it on my boat trailer bearings three years ago and haven't had to regrease them yet.

www.krazygrease.com

Not trying to start a war, but I have to personally disagree with the marine grease idea; tried it, it failed. I'll stick with the Slick 50 One grease I have in tubs. (One tub still unopened after a decade, the other still about half-full -- it's GOOD stuff!)

I WILL, however, use the marine grease in low-stress apps, like the seatpost, threads, and such.