I have a tube of Phil Wood (the green kind) waterproof grease that I bought 6 years ago when I first started riding. I have used it to rebuild pedals (crank bros) grease threads, etc.

Now I have 3 cup & cone hubs to rebuild. I've pilot rebuilt one of them (to teach myself the process and how to adjust them just right) using this grease. Now I'll go in to rebuild these wheels with new balls and all, should I use this 6 year old grease or get a fresh tube? I haven't left the cap off etc, so by all appearances it looks like it did when I bought it.

TIA

I think you're good to go. I have a can of automotive wheel bearing grease around my garage that must be 30 years old, and it's still fine. Heck, I'm a gun collector and have a couple of M1 rifles, and I have some of those little-bitty jars of Lubriplate with the yellow screw top that was issued to grease the M1's during WWII, and it's still good.

Yes, you will be just fine. Just to add to tpelle's example....some industrial machinery have service intervals ("re-greasing") of over ten years. Grease does last that long, even while in use, if it's good stuff.

the shelf life of grease in a closed package is probably a century or so. Most grease goes bad, not because of any chemical problem, but because open containers get contaminated with all kinds of stuff.

Visit any bike shop and you'll find an open tub, collecting dust, and whatever is introduced by the brush which is used to apply it, and return dirt back to the mother ship. The smart way to buy grease is in tubes, or if in tubs, to transfer a small amount to a piece of scrap paper or foil, use what you need, and discard the rest. Otherwise all your effort to repack bearings in clean room conditions will be for naught.

Grease is oil suspended in a wax. If the two are still together, the grease is good. If they separate, it's bad. If you have a can or tube that has a lot of oil floating on top, or it's just a dry mess, throw it out.

You're more likely to see separation in very old used grease, particularly if it was exposed to high temperatures. This should be thoroughly cleaned off before new grease is applied.

Yup, you would be fine.

Campy grease tends to separate after many years. I have a pair of NR pedals I bought new over 30 years ago. When I put them on a bike last year, they were very stiff. Since they were clean, not rusty and well packed with their original grease, I decided not to repack them. They got free and smooth when I added a little motor oil. I suspect the oil in the original grease evaporated and the oil I added quickly emulsified in whatever exotic wax or fat Campagnolo used in their fragrant grease.

Grease can go bad if it becomes fearful. As Master Yoda says, "Fear leads to anger; anger leads to hate; hate leads to suffering."

If your lubricant has become fearful it has begun the journey toward the dark side of the grease. Remember, fear is the mind-killer...

The best advice I have read here is the grease is bad if there is separation. Example--if it is in a can and there is oil on top throw it out. Im still using Phil Wood grease in a tube that is several years old. If grease is in a tube, there will be very little air (oxygen) to degrade the grease.

I don't think that it is the air that is degrading the grease (as in oxidation) but it is simply a matter of the more volatile petrochemicals evaporating out of the grease itself to leave only the waxy binder behind. It takes decades for this to happen, and only because enough fresh air is exposed to accept it all. It's a very slow process and can't happen in a sealed container. The oils themselves are very chemically stable as grease is designed to last a long time under conditions that are far harsher than typically experienced in a bicycle. Veggie oils can oxidize (go rancid) much easier and quicker but the oils in grease are designed to not oxidize like this for many, many years.

Most likely the only thing that may happen with grease is that it might seperate like you said. The oils and waxes are no longer in suspension. You might be able to mix it back up but grease is inexpensive -why bother? I buy it in in the 16oz tub for $5 at the local autoparts store. I like the Castrol NLGI #2 silicon-based grease because it is cheap and works well. I also like the way it smells

I use the green stuff given to me by another cyclist. Just bought a 1lb tub of Valvoline Dura Blend moly-fortified synthetic blend NGLI #2 lithium EP grease (PN VV278) at Autozone. It's $5, minus instant $5 off $5 coupon. The Valvoline has a lower coefficient of friction. There's no need to spend more $ on green grease.

The valvoline stuff is good too and also widely available. NGLI #2 is NGLI #2 is NGLI #2... When I work on vehicles (Car/truck/motorcycle/boat) I use the type of grease specified for the fastener/bearing/bushing/whatever. But I never concern myself about the brand name or if it is a high-end boutique blend. That's just marketing. I'm glad Phil is making a bunch of money selling grease at 10x the cost of commercial fleet equivalents. Good for him. But I'm not going to spend my money on the hype. Oh, how the boutique-synthetic/dino lube flame wars have raged even before the internet was invented.

$5 plus $5 off coupon? Free is even better! I wish I would have happened upon such a promotion. I'm 3/4 done with my 16oz tub I bought years ago. Sooner or later I'm going to need more.

Well, yes, but NLGI number is not the only specification that matters. The number is merely an indication of its consistancy. It doesn't tell you anything about what the soap is, what the viscosity of the oil is, nor what additive package is in use. all of that matters.

The Eagles One Gel Wax is also on sale for $4 @ AZO, minus the coupon (purchase price up to $10) found in auto magazine. Final cost is 35 cents plus stamp.

Advanced Auto Parts shows a sale price of $3.33. O'Reilly has Eagle One products (including Gel Wax) 2/$7 through 03.29.11.

https://shop.advanceautoparts.com/web...116-_-10716090

In an internal-combustion engine, automobile axle, or high RPM/high load application; yes. On a bicycle bearing; not so much...

The most important criteria for a bicycle grease is the ability to hold lose BBs in place during packing. Some prefer the super thick green grease. The temperature, rpm, and load are so low on a bicycle, that one shouldn't fret over film strength or additives. I personally look for a little moly in the grease. If the grease is too thick, then there will be excessive drag on the bearing after rebuild.

Contamination is the #1 enemy of grease. It's always a good idea to clean/repack with new grease every 5K miles. Cut the interval by 40% if you ride in the rain.

"Gluing" the bearings in

I also like the way it conditions the skin on my fingertips and makes it so soft and silky feeling after a days work.

no, it matters on a bike. Corrosion resistance, resistance to wash out, and compatibility with existing lubricant all matter. In some applications, traditional headsets for instance, ability to lubricate in boundary situations matters. It's not hard to buy a grease that meets the requirements of bike use, but it's not hard to buy one that doesn't either, particularly for water resistance and compatibility with existing lubrication.

Through my work I have tested many greases under demanding industrial conditions, and my experience has been that many (most) greases are still good after there has been some separation. Mix the oil back in and apply as needed. I expect there is a point where the oil separation becomes a problem - like when the substance left behind under the oil is dry and cracked, but we never tested grease in that condition. But a little bit of separation can happen to even the best performaing greases after a relatively short time, and the performance of the grease does not suffer.

For example... we have a particular grease often used for greasing the threads on rising stem valves that has always proved consitent in testing. When we were concerned that our instruments were not functioning properly we would use that grease to conduct baseline tests and we could tell by the measured coefficient of friction between the valve stem and nut if the instruments were reading properly (this is when everything is in calibration, but we just want to convince ourselves that an outlyer test sample really was behaiving strangely and we are not crazy). We would go back to the cupboard where the sample greases were kept, took out our favourite, mixed in the separated oil and ran the test, and it performed fine.

Sounds just like ad copy. You don't happen to be affiliated with a high-end grease/oil manufacturer or distributor? Or maybe you just bought it HL&S and need to believe this.

As for "Compatibility with existing lubrication" who doesn't completely remove the old grease? It's old and, like it was mentioned above, contaminated. Clean it all off and put new grease in. Mixing new grease with old on a bicycle is lazy. There are no grease-zerts on most bikes. Why bother tearing down a BB, wheel hub or headset if you are not going to clean the old yucky grease 100% out?

It's very common for shops to add grease to the bearings on new hubs. I've injected grease into sealed bearings using a needle, and I know others do that too. I don't see any reason to use solvents on parts that I'm taking apart for inspection, and have shown themselves to be clean, free of contamination and not worn.

Before you call me names, do pay attention to what I actually wrote, and not what you'd like to pretend I wrote. I expressed no opinion about the suitability, or lack thereof, of any particular product. I merely made an entirely factual statement that there is more to grease specification than just its NLGI number. I'm on the record as saying I won't use grease from Phil, Park, or any of the other bike grease specialists, not because they make inferior or unsuitable products, but because they don't publish their spec sheets. I can't make a judgment of their suitability without it, so I don't, and use perfectly acceptable grease obtained elsewhere. That it's the same grease I use on lots of other equipment is just a bonus.

Even worse than grease going bad, I hate it when my gojo goes bad. That stuff makes a mess.

I was at the bearing place late last year ordering the grease I use and asked. The clerk showed me a tube with an expiration date on it. That was news to me. Some of the additives are volatile and that must affect shelf life.

A reputable bike shop would never add grease to the bearings!

If the part is clean and free of contamination, then you don't need to add grease because it's sealed so well that nothing can get in or out. Gee, I need to invest in this company.

Probably some high-performance MIL SPEC grease. Very common in the aerospace industry. Even stuffs like RTV come with expiration date. Course one can always re-cert a batch that has gone past expiration.