EPete,

I helped switch a customer because all the new motors were coming in with Polyrex EM, and the motor rebuild shop we use puts Polyrex EM in all the rebuilds.
I talked to two different Mobil lube engineers and received two different responses. One said no problem just pump it in (100% compatible), the other said to get as much of the mobillith 100 out of the cavity as possible (barely compatible) and then pump it in. We took that advice since I didn't like the polyurea in with clay base. We haven't had any problems (been a couple of years now I believe). One motor that lost a winding had some funky looking grease in the cavity, but it was still mostly blue and was still pliable and providing grease (looked somewhat like a soft soap).
We use a wooden dowel and clean out as much as possible from the vent pipe or cavity (depending on manufacturer) before greasing.

D

I switched our plant to Polyrex EM because new motors are coming from the factory with it, I did not want to be mixing greases constantly and because it has a less tacky consistancy then SHC100 I felt it would come out the drains better as well as possibly not push through the seals as easily should the motors be over lubricated. We have not had a problem with SHC100, but I felt the Polyrex is better suited for motors. I do use SHC100 on the pillow block bearings of an overhung fan and this grease does tend to plug the reliefs, so I am hoping the Polyrex will work better. At least it should not be any worse.

We did not have any compatibility issues, a 500 hp motor recently failed due to a winding fault and I inspected the motor at the motor shop and found no incompatibility issue with the grease at all. Both greases could be seen in the housing and the consistancy of both was just fine, so I am convinced there is not a compatibility issue with these greases. This motor probably had 6-9 months of the Polyrex in it, so if there were any problems, I am certain I would have seen them by then.

We also use automatic lubricators from Perma on all our large motors, so with the continuous greasing I felt the texture of the Polyrex would work better with the grease reliefs we installed on the motor grease drains. I don't know yet if the reliefs actually work since the housings are not full of grease, but that is my hope. I have also heard the Polyrex grease can last longer then the SHC100, so the regreasing intervals can be reduced. I don't know if that is true or not, but we will see what the grease looks like after we get a few years run time in the motors and determine if we can reduce the quantity we use.

I have significant experience with both products. Bottom line is this,most electric motors come new with polyurea. EM grade bearings are almost always prelubricated with polyurea. For those two reasons alone it makes sense to use polyurea grease in most of your electric motor applications. I come from the rotating apparatus repair industry and almost all service shops have standardized on polyurea for those same reasons. Don't fix what ain't broke.
One caveat to this is "might" be DC motors. I worked for GE for several years. Their OEM grease on motors that didn't have commutators or slip rings was polyurea. However if carbon brushes were involved they used lithium complex. The claim was just like silicon, it prevented proper filming. The service shops I worked for over the years used polyurea in DC motor rebuilds and it really didn't appear to be an issue, but that was GE's position on the matter.
I also worked field service for an industrial fan and blower company, we primarily used TECO and Baldor motors on our fans. Both of which came standard with polyurea grease. We recommended using it. However, SCH100 was our standard grease for the fan pillow blocks. This became especially critical on double row sphericals. Lightly loaded bearings like double row sphericals on a fan are vulnerable to seizure type failure if the grease is stiff or tacky. EP additives are enough to cause it. Through years of headaches and warranty issues they found success with SHC100.

Thanks all. That is good info... I’m still digesting.

One question for P ZRT... I can’t quite make sense of this:

quote:

I also worked field service for an industrial fan and blower company, we primarily used TECO and Baldor motors on our fans. Both of which came standard with polyurea grease. We recommended using it. However, SCH100 was our standard grease for the fan pillow blocks. This became especially critical on double row sphericals. Lightly loaded bearings like double row sphericals on a fan are vulnerable to seizure type failure if the grease is stiff or tacky. EP additives are enough to cause it. Through years of headaches and warranty issues they found success with SHC100.

Are you saying the pillow block bearings had problems with Polyrex and did better with SHC100?
Are you saying EP additives caused problems for this particular application?
Are you saying the Polyrex had the EP additives that cause the problem and Mobilth SHC100 didn’t?
(I associate EP additives with Mobilith SHC100, not Polyrex EM).

Pete...Yes I am saying SHC100 did better in "some" applications than polyurea (more so with shear stable)

Yes I am saying EP additives cause problems in lightly loaded bearings like double row sphericals on a fan

No...I didn't mean to indicate polyrex had EP additives and SHC100 didn't...in fact SHC100 does some EP additives. However the synthetic fluids in this grease have proven to counter act the effects of EP additives. The same results can not be expected with a standard lithium complex EP grease.

That is interesting info on the SHC100 and the fan pillow blocks. We are using this grease in our fans and have had good luck with it to date.