Can I add a Pour point Depressent to a finished grease?

[Rafe Britton]

Hi @Tania.bkt ! What’s the issue that you’re facing at low temperatures? Typically it is the thickener that becomes too thick (which isn’t solved by adding a PPD). I’d be hesitant to add any additives to a grease after it has been formulated, as the manufacturing process usually requires the additive mixing in a very controlled environment.

[Tania Juarez]

Hi Rafe, well I have a lithium grease tha is certificated by NLGI LB, and one of the test that the grease must fulfill is ASTM D4693 Low Temperature Torque @40°C 60 second Torque, the max. specitification is 15.5 N-m. Our grease is using Group I and the restult is 16.32 N-m. I think the best option is to chenge the type of basic oil but I just wander if adding PPD could help to improve the behavior of the grease to fulfil this test at low temperature.

[Rafe Britton]

Ahh – I see what you mean now. It really depends on the cold-temperature behaviour of the base oil as to whether a PPD will make any difference. PPDs inhibit wax crystal growth – if these crystals are emerging at -40C than the PPD would potentially make a difference to the cold flow properties. However, I’m not sure about blending it in to a fully-formulated grease. PPD’s are an additive that require heat blending into lubricant formulations, so I’m not sure how you’d get the homogenized in the correct way in an already-manufactured grease.

[Tania Juarez]

I appreciate your response, I will make some experiments about it!