Grease with embedded metal flakes

[Corniit]

Dear All,

I'm stumbled with grease issue I can't figure out what is going on. Some time ago I bought Valvoline multipurpose lithium EP 2 grease what I've been using for greasing my milling machine linear guiderails. Machine is mid nineties and didn't have oiler so manual grease fittings. Yesterday when adding grease to my gloves for manual apply to ball screw I noticed metal flakes embedded in the grease. I got really nervous as I've been applying the same grease to the slides for many times already. Pumped few times to see if those metal flakes reappear and they did. Was wondering if they were EP additive flakes like graphite or something. Decided to change the grease cartridge to new one today and continued maintenance. With the new cartridge got the same issue. Extracted the shiny particle and it really was steel.

I've been trying to contact Valvoline Europe, but can't get anyone to reply on me. Those both cartridges were bought the same time and are with the same batch number. What do you think, is there any possibility that the grease could have these embedded somehow? I can't think of any way that the grease gun pump mechanism could do this. It is Pressol gun so should be good quality. And I've pumped almost complete 400g cartridge through it so possible particles left from manufacturing should have long gone. Been thinking also if some of the bad grease with embedded metal chips came back when pumping the grease. But that sounds just impossible as the grease nipples have one way ball valves. Please see attached picture of flakes in the grease.

Thank you in advance

 

[Kestas]

It certainly does look like contaminant particles in the grease.

One other thought... could the grease tube ends have had some grit thrown on it in the shop before use?

If the pattern of contamination is uniformly dispersed throughout the grease, that would point more toward contamination by the manufacturer.

 

[Corniit]

Thanks for your reply. What comes to the grit getting in the time of cartridge apply to the gun is out of question. I was the one to install them on both times and had fresh gloves and not even close to metal chips. Now second time I particularly paid attention that both ends of the cartidge were dirt free. Also emptied and cleaned the gun before the new cartridge.

Valvoline US had great support. There is even online chat, but unfortunately they are not commenting European Valvoline products, which is understandable.

 

[DriveHard]

I have seen this before, and it seems to be the shiny metallic covering they put on the label as it overlaps into the tube. I have never given it a second thought.

 

[ABN_CBT_ENGR]

Something is clearly amiss but honestly, it would be virtually physically impossible for this type and level of metal contamination you say you are experiencing to come from the manufacturing end.

Theres just almost no way the grease is even exposed to machines that would generate it from the retorts, mixers, kettles and to the loading injectors.( it would most likely clog the loaders)

Then almost certainly magnetometers would register it.

where and what else have you checked?