What About XHVI.....

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What about Shell's XHVI, which is a grp. III oil? I saw somewhere that it is superior to other grp. IIIs. Someone please fill me in a little on it. Thank you.
 
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Yes, XHVI is superior to most other Group III base oils. The reason is how XHVI is made. Regular Group III base oil is made from hydrocracking and isodewaxing the VGO (vacuum gas oil) from the crude oil distiller. This VGO is the "feedstock" for regular Group III. The undersirable elements of the VGO are "cracked" using a catalyst under high heat and pressure in the presence of hyrdrogen, coverting them to saturated parrafin molecules (the good stuff in any hydrocarbon base oil). The resideual wax molecules in the VGO are isomerized into fully saturated parrafin molecules. The result is an almost pure, fully saturated base oil with a VI of around 120-130. XHVI (as well as ExxonMobil's ExxSyn) are pure wax isomerates. The feedstock used to make them is not the VGO from the distiller, it is either (1) slack wax, or (2) waxy raffinate. "Slack wax" is basically just what the name implies: it's pure parrafinic wax, about the consistency of Vasoline. It is the byproduct of solvent dewaxing the VGO in the production of Group I and some Group II base oils. "Waxy raffinate" is also a wax byproduct of the refining process used to produce diesel and fuel oil. Waxy raffinate can also be produced synthetically, which is what Shell is doing now using their new GTL (gas to liquid) technology. To produce XHVI, either of these wax feedstocks are isomerized into a pure, fully saturated paraffinic base oil with a VI of more than 140 and a pour point that is about 10-15 degrees lower than regular Group III. This is the primary benefit of XHVI (or other wax isomerate) over regular Group III: it has a higher VI and lower pour point, as well as being a more chemically pure base oil. When it comes to Group IIIs, XHVI or ExxSyn come the closest to matching the performance levels of PAO.
 

MolaKule

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And I think this is the reason why Chevron's PCMOs, Gear Lubes, and hydraulic oils are superb "Sleepers."
 
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Sounds like Chevron's base oil: "The ISODEWAXING® catalyst reshapes wax molecules into high-quality base oil molecules rather than breaking them down into by-products as is done in conventional catalytic dewaxing. The result is a chemically pure, clear, high-VI, low-pour-point base oil with outstanding performance characteristics." "The higher purity and VI levels of ChevronTexaco UCBOs make them exceptionally resistant to oxidation. In tests, ChevronTexaco UCBOs produce oxidation stability approaching that of polyalphaolefin synthetics, making them ideal for lubricants where longer life is required, even under the highest operating temperatures." "More Stable Viscosity: ChevronTexaco UCBOs have very high VIs, providing more stable viscosity at extreme temperatures. So lubricants thicken less at cold temperatures and thin less at high temperatures - providing better wear protection and longer equipment life....UCBOs have very high viscosity indices ranging from 120 to 140 VI compared to conventional neutral base oils at about 95 VI." "Lower Volatility: The higher VIs of ChevronTexaco UCBOs also help make them much less volatile, or less prone to evaporation." Some base oil info: http://www.chevron.com/prodserv/BaseOils/comp_med.shtml Ken [ February 06, 2004, 04:36 PM: Message edited by: Ken2 ]
 
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quote:
Originally posted by Ken2: Sounds like Chevron's base oil: "The ISODEWAXING® catalyst reshapes wax molecules into high-quality base oil molecules rather than breaking them down into by-products as is done in conventional catalytic dewaxing. The result is a chemically pure, clear, high-VI, low-pour-point base oil with outstanding performance characteristics."
Chevron's UCBOs (they call their Group III "Unconventional Base Oil") is not the same thing as XHVI. The isodewaxing process is similar, in that the same catalytic process is used to convert the wax molecules in the VGO to fully saturated oil molecules. The difference is that this is just a part of the process for UCBO, the dewaxing process. The main part is the hydrocracking of the VGO. XHVI (or any wax isomerate) is produced SOLELY by wax isomerization. As I said, the feedstock for XHVI is not oil at all, but is slack wax or waxy raffinate. So with UCBO, only a minute part of the feedstock (the residual wax) is isomerized, while with XHVI, the sum total of the feedstock (which is wax) is isomerized into oil.
 
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