I have used Mobil 1 red synthetic grease to lube the chassis in my Silverado ever since it was new. Kind of curious though, when I re-grease the chassis, the old grease that seeps out is jet black. It was red when it went in there but it come out black when it is done for. Why does it change color?
Grease goes in red comes out black
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Kestas
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If the original grease is long gone, what you are seeing is the slight fretting between the metal surfaces, which mills ferrous debris into the grease. This turns it dark.
Same reason ANY lubricant goes in nice and pretty and comes out later looking less pretty, the lubricant is doing its job.
Dirt, water, soot, etc ingress?
Originally Posted By: Kestas
If the original grease is long gone, what you are seeing is the slight fretting between the metal surfaces, which mills ferrous debris into the grease. This turns it dark.
I think this is what is happening. The OE grease is long gone. The truck is 11 years old. I was hoping it wasn't ferrous wear metals because that would mean that my grease is not providing a total barrier between the metal parts... but perhaps this expectation is unrealistic. I don't think it is ingress of anything as the rubber boots are all in great shape. Thanks for all the replies so far.
If the original grease is long gone, what you are seeing is the slight fretting between the metal surfaces, which mills ferrous debris into the grease. This turns it dark.
I think this is what is happening. The OE grease is long gone. The truck is 11 years old. I was hoping it wasn't ferrous wear metals because that would mean that my grease is not providing a total barrier between the metal parts... but perhaps this expectation is unrealistic. I don't think it is ingress of anything as the rubber boots are all in great shape. Thanks for all the replies so far.
Kestas
Staff member
Originally Posted By: k1rod
Originally Posted By: Kestas
If the original grease is long gone, what you are seeing is the slight fretting between the metal surfaces, which mills ferrous debris into the grease. This turns it dark.
I think this is what is happening. The OE grease is long gone. The truck is 11 years old. I was hoping it wasn't ferrous wear metals because that would mean that my grease is not providing a total barrier between the metal parts... but perhaps this expectation is unrealistic. I don't think it is ingress of anything as the rubber boots are all in great shape. Thanks for all the replies so far.
You may be right that your expectation is unrealistic. Ball joints and tie rod ends are boundary lubricated, as opposed to roller bearings, which develop their separating film with the lube. Boundary lubrication will always result in some wear. I've never seen old grease come out anything but black when lubricating the chassis.
Originally Posted By: Kestas
If the original grease is long gone, what you are seeing is the slight fretting between the metal surfaces, which mills ferrous debris into the grease. This turns it dark.
I think this is what is happening. The OE grease is long gone. The truck is 11 years old. I was hoping it wasn't ferrous wear metals because that would mean that my grease is not providing a total barrier between the metal parts... but perhaps this expectation is unrealistic. I don't think it is ingress of anything as the rubber boots are all in great shape. Thanks for all the replies so far.
You may be right that your expectation is unrealistic. Ball joints and tie rod ends are boundary lubricated, as opposed to roller bearings, which develop their separating film with the lube. Boundary lubrication will always result in some wear. I've never seen old grease come out anything but black when lubricating the chassis.
Originally Posted By: Kestas
You may be right that your expectation is unrealistic. Ball joints and tie rod ends are boundary lubricated, as opposed to roller bearings, which develop their separating film with the lube. Boundary lubrication will always result in some wear. I've never seen old grease come out anything but black when lubricating the chassis.
Thank you Kestas, that is very helpful!
You may be right that your expectation is unrealistic. Ball joints and tie rod ends are boundary lubricated, as opposed to roller bearings, which develop their separating film with the lube. Boundary lubrication will always result in some wear. I've never seen old grease come out anything but black when lubricating the chassis.
Thank you Kestas, that is very helpful!
Originally Posted By: k1rod
I didn't realize I was. How so?
Sorry for the delay in response.
Because of the boundary film that Kestas referred to, pure chassis lubricants are usually spec'd with at least 3% moly.
The general purpose Mobil 1 product you're using does not include this.
I didn't realize I was. How so?
Sorry for the delay in response.
Because of the boundary film that Kestas referred to, pure chassis lubricants are usually spec'd with at least 3% moly.
The general purpose Mobil 1 product you're using does not include this.
Originally Posted By: Ramblejam
Because what you're likely seeing is OE grease being pushed out, which is fortified with 3% moly and would appear black.
What he said!
Because what you're likely seeing is OE grease being pushed out, which is fortified with 3% moly and would appear black.
What he said!
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