de-waxed oils and cloud points

[Ray H]

You're not crazy. An oil's cloud point is the traditional way of expressing formation of wax precipitates, but the definition may have to change in the not too distant future. First of all, as you implied, PAOs do NOT have any wax content. Zip, zero, nada, nothing, nichts. But, if even PAO base oil is chilled to its freezing point, the resulting mass wouldn't likely be transparent. If that's true, and presuming freezing to a solid block would not be instantaneous, it follows that the first and increasingly numerous microcrystals of PAO suspended in the liquid would result in an increasingly cloudy appearance. Whether Group IV PAO base oils become the predominant lubricating base oil eventually isn't relevant or likely. But GTL "Super Group III" base oils polymerized from methane gas could eventually become a heavy hitter commercially. Being a synthesized product that starts life as the simplist hydrocarbon (CH4), there won't be any wax in it either. It, too would likely have a cloud point unrelated to wax crystal formation as it approaches its freezing point.

 

[bruce381]

Actually PAO as it cools will just get thicker until it "freezes" At pour point oils are just a grease consistancy not a ice block.
bruce

 

[bruce381]

Also De waxing can de done with solvents or catalytically and in both cases some "wax" or heavy molecules remain which will still cause some hazy upon cooling down to the cloud point.
bruce

 

[Curious Kid]

Call me crazy, but if an oils cloud point is the temperature when wax crystals begin to develop in an oil, then how can oils that have gone through de-waxing processes still visually present such a phenomena? To me, it would be better served to say the oil has gone through a wax reduction process rather than de-waxing/stripping process...the latter sounding too complete. I do understand there's limitations, but...

Could there be more to explain the clouding of such a refined oil, and do PAO's and the newer breeds also have a visual clouding point that may deminish wax crystals as the cause?

Thanks in advance.

 

[Curious Kid]

Thanks again guys.

I was reminded of how the term synthetic could be aplicable to include group 3 oils in a freezer chill test on a 5w-20 oil, having seen it cloud up at 0 to -5 deg.f below. I wish M1 still had 0w-20 and was of the SL formulation (for winter top-up)...oh well.

 

[Curious Kid]

While I have you...does anyone think it would be a bad idea to use M1's new SM formulation 5w-20 as top-up with a crankcase containing Castrol syntec 0w/5w30 mix for winter in a modular engine used for short trips/infrequent use? I've heard M1's additive blend appears different from the rest.

Sorry elves...just looking to save some gas and further aid in cold flow.

Thank you.

 

[Ray H]

Never said PAOs became a hard "ice" block, but it would be a semi-solid glop. I simply offered that whatever consistency frozen PAO took, it would not likely be transparent and that before the full mass froze, the transitional liquid would probably take on a cloudy appearance. Very little wax remains in hydrogen isomerized-dewaxed Group III base stock. All but single digit percentages have their waxy sidechains isomerized into very desirable branched chain compounds with good lubricating qualities. The little remaining wax in Group III base oils respond extremely well to pour point depressants. Quite a bit of residual wax (relatively) remains after solvent aided chilled wax extraction and simple filtration.