Anyone know any reason why I should not use Mobilgrease 28 that is about 10 years old but sealed in the 5 gallon pail? This would be for auto use, not aircraft use. The pail says 36 month shelf life but my guess is that is for aircraft use. I don't know too much about how it would degrade over time in a sealed can. It was cheap and could not pass it up.
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Mobilgrease 28
- Thread starter rgl
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Assuming the old adage "you get what you pay for" does not apply, let's look at this product and how you intend to use it.
Mobilgrease 28 is a synthetic aviation grease. It's about a grade 1.5 (between an NLGI 1 and 2) that "is designed for the lubrication of plain and rolling bearings at low to high speeds, and splines, screws, worm gears, and other mechanisms where high friction reduction, low wear, and low lubricant friction losses are required". Although not the typical choice of automotive enthusiasts (especially considering the price of a new pail), it offers, at a minimum, similar performance to the baseline "EP 2" grease typically called for in your application.
The two things I would watch out for are:
a) Look at the appearance of the grease. If it still appears homogeneous as well as "smooth and buttery" (vs. hard or with a lot of oil separation), it should still be OK for use.
b) Watch for indications of incompatibility with the old grease. Typically, when incompatible greases are mixed, the dropping point (or ability to handle high temps) is reduced and the measured NLGI grade of the combined greases is reduced (say from a grade 2 to a grade 1). This will manifest itself as excessive grease running out of the application.
Mobilgrease 28 is a synthetic aviation grease. It's about a grade 1.5 (between an NLGI 1 and 2) that "is designed for the lubrication of plain and rolling bearings at low to high speeds, and splines, screws, worm gears, and other mechanisms where high friction reduction, low wear, and low lubricant friction losses are required". Although not the typical choice of automotive enthusiasts (especially considering the price of a new pail), it offers, at a minimum, similar performance to the baseline "EP 2" grease typically called for in your application.
The two things I would watch out for are:
a) Look at the appearance of the grease. If it still appears homogeneous as well as "smooth and buttery" (vs. hard or with a lot of oil separation), it should still be OK for use.
b) Watch for indications of incompatibility with the old grease. Typically, when incompatible greases are mixed, the dropping point (or ability to handle high temps) is reduced and the measured NLGI grade of the combined greases is reduced (say from a grade 2 to a grade 1). This will manifest itself as excessive grease running out of the application.
rgl
Thread starter
Thanks. The stuff looks just like Mobil 1 grease, but darker. No separation. I think it may be incompatible with Mobil 1, which is what I use now. I think Mobilgrease 28 has Bentonite.
Actually, if my memory serves me right, the thickener is a "sodium synthetic". It's definitely not a lithium complex like the Mobil 1. I, too, would question compatibility but you would have to test it to be sure.
Ok, you got me interested. Where can you buy Mobilegrease 28 in the Houston area, I only need a tube of it for a lincoln hand grease gun.
http://store.avlube.com/mobilgrease28.html
One of the site sponsors sells it, also possibly lubrication distributor may carry it
http://www.prod.exxonmobil.com/channelpartners/mn_dist_detail_state.jsp?state=tx
One of the site sponsors sells it, also possibly lubrication distributor may carry it
http://www.prod.exxonmobil.com/channelpartners/mn_dist_detail_state.jsp?state=tx
Mobilgrease 28 is an an excellent wheel bearing grease although not the greatest with respect to water washout. i.e. NOT a good boat trailer wheel bearing grease. It is a clay base thickener and does have some mild compatability issues with lithiums, etc.. It has pretty much been replaced by Mobilith shc100 aviation grease which is a lithium complex grease. The original mil spec called for a -60 operation, which necessetated the clay thickener. It is an ISO 32 base oil and was used as the space shuttle wheel bearing grease for quite a while.
As long as the grease has not separated too much and has not been exposed to temperature extremes during storage, should be fine for bearings. Keep in mind, less is best.. This is a very high quality grease and 1/3 full is the rule.
George Morrison
AV Lubricants Inc.
As long as the grease has not separated too much and has not been exposed to temperature extremes during storage, should be fine for bearings. Keep in mind, less is best.. This is a very high quality grease and 1/3 full is the rule.
George Morrison
AV Lubricants Inc.
Origianally posted by George CLS
In the NLGI paper The Influence of Thickener Type On The Apparant Viscosity of Lubricating Grease They use a PAO-6 oil in different thickeners to examine the viscosities under different temperatures and shear with a brookfeild viscometer.And the clay at -40 had a viscosity of 288,000 poises,and the lithium complex was 173,440 poise at 1 RPM.
How or why would clay be a better choice over cold temperature use when it looks like the lithium shows less of an increase in viscosity and I would think less starting torque.What would be the determining factor that I'm probably missing?
Is that the ASTM D 1478 low temperature torque test.quote:
The original mil spec called for a -60 operation, which necessetated the clay thickener.
In the NLGI paper The Influence of Thickener Type On The Apparant Viscosity of Lubricating Grease They use a PAO-6 oil in different thickeners to examine the viscosities under different temperatures and shear with a brookfeild viscometer.And the clay at -40 had a viscosity of 288,000 poises,and the lithium complex was 173,440 poise at 1 RPM.
How or why would clay be a better choice over cold temperature use when it looks like the lithium shows less of an increase in viscosity and I would think less starting torque.What would be the determining factor that I'm probably missing?
rgl
Thread starter
Sorry to report, I have not actually used any of the Mobilgrease 28 since I bought it. I am going to save it for when I get a military vehicle (notice the when not if). This is mostly due to the probable compatibility problems with regular Mobil 1 grease I use right now. The Mobil rep at the Oshkosh fly in said the grease probably would not be good for automotive use but I can't see why it would be ok on US Navy aircraft wheel bearings in & out of carriers and not on a puny Ford truck. BTW I got it for $15 for the pail + shipping from Coleman's Military Surplus, I think they still have it. It is labeled as being for carrier catapults.
Frankly the military is no longer using Mobilgrease 28 in wheel bearings; it has progressed to a lithium based ISO 100 synethetic. Primarily due to the rather poor water washout characteristics of the clay thickened Mobilgrease 28. Mobil Aviation SHC 100 is now becoming the grease standard for aviation wheel bearings, especially high speed fighters.
George Morrison
George Morrison
Does anybody know a good alternative/equivalent grease to Mobil 28? I work at a medical device companies and have received complaints that the red Mobil 28 looks like blood. Exxon rep said Mobil 33. Especially concerned with viscocity and water evaporation. Thanks!
Water evaporation?
The 33 appears to be a very good grease, but I bet it is expensive. They don't give the base oil vis. on the data sheet but it has a very low starting torque so it's a good bet that the oil is fairly thin.
The 28 uses a thin base oil as well.
The 33 appears to be a very good grease, but I bet it is expensive. They don't give the base oil vis. on the data sheet but it has a very low starting torque so it's a good bet that the oil is fairly thin.
The 28 uses a thin base oil as well.
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