What does pour point mean for a lubricant?

Pour point - it's important if you're operating in a temperature with very low temperature extremes, but what influences the pour point of a lubricant - and generally the low temperature behaviour of lubricating oils?

[@LubricationExplained]

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[@nuwagababonner5618]

Wonderful. this is the only video on the internet that clearly explains pour points

[@LubricationExplained]

thanks so much!!

[@sunilmehta1519]

You are a great teacher. Keep it up and enlighten those who are interested and those who are in the field of lubricants

[@LubricationExplained]

Thanks!

[@mohamedelyas9294]

Quite difficult subject, but you made it so good !

[@LubricationExplained]

Thanks!

[@luizfernandopaquieli3709]

Great explained! Thanks for share it

[@LubricationExplained]

Thanks! Glad you're able to make use of it.

[@mytech6779]

I know cloud point is important when a system has filters because plugging will result. This is one of the primary concerns for jet fuel. And most jet aircraft use a lubeoil to fuel heat exchanger just prior to the engine fuel filter, as well as temperature monitoring of tanks for pour point(pumping point).
If people want an easy near room temperature demonstration(30-50c) I suggest a soft grade microcrystalline wax.(cheese waxes are based on soft MC wax so may be suitable, but many are also blended with other waxes and texture modifiers.)
Unlike common parraffin candle wax, microcrystalline waxes are complex mixes and do not have a sharp freeze temperature. So in product data microcrystalline waxes use a drop point and a congealing point. For most commercial grades the drop point is approximately 10 degrees above the congeal point. They are analogous to the cloud point and pour point of lube oil. The other useful visual here is that the liquid when just above the drop point has a relatively low viscosity making it obvious that the pour point effect is quite different from the simple rise in viscosity with cooling. MC wax also transitions from transparent to cloudy between these points.
The drop point is when a liquid drop falls from a standard thermometer that was coated in solid wax then slowly heated.
The congeal point is had by dipping a warm thermometer in fully liquid wax then holding it mostly horizontal and slowly rotating it in a slowly cooling flow of air until the droplet gels and start to rotate with the thermometer, this gelling is rather sudden and the movement similar to a droplet properly frozen to the thermometer, it is quite unlike a high viscosity fluid such as twirling cold honey; the droplet will still be a gloopy non-solid if touched at this temperature but it is also neither sticky nor a proper flowable liquid. I do not know if it has a thixotropic nature.

[@LubricationExplained]

You've mentioned jet oils a few times - do you have an aviation background?

[@mytech6779]

@@LubricationExplained yes I have some aviation background. But I mainly use planes as good examples for environmental extremes.

[@jediali221]

Fascinating, thanks!

[@LubricationExplained]

Glad you found it helpful!

[@adws5696]

Super interesting

[@LubricationExplained]

Thanks!

[@shahadsaad7330]

Hello it’s great explaining
Is the density of flow change ! Or only the viscosity

[@tomasnokechtesledger1786]

Hello Mr. LE, does PPDs act by postponing wax formation for the same cold temperature? Are only used in mineral and semi?

[@LubricationExplained]

Good question. So I believe that wax formation still occurs at the same temperature (the cloud point remains relatively unaffected) but it disrupts the way that the wax crystals are able to form a gel matrix - this helps to lower the pour point. I don't imagine you would see too many PPDs in synthetic oils because PAOs contain virtually no paraffin molecules.

[@jozefsk7456]

Does Any of you have a family heirloom bucket of grease? :D My grandfather gave it to my father as something he yanked or got from a job, this thing sat in the garage for at least 60 years at this point, and I used it for the first time yesterday. It had a thick plastic like crust on the top, but underneath it resembled a grease. Dont crucify me lmao, I know this is blasphemy :D

[@LubricationExplained]

Not at all! That's a great demo of shelf life.