Base oil's natural viscosity index...?

[Curious Kid]

What's keeping the natural viscosity of processed oils - mineral oils, from becoming any higher than they are? Cost aside, and I suppose market necessity as well...what's the snag? Group 3 with cracking, cat. dewaxing, hydrogen saturation...don't quite have a "back hand" knowledge of it all, but none the less curious at better understanding the limiting factors. Thanks in advance for any contributions.

 

[bruce381]

crude type used to determine what VI you got but now with the Hydrotreating and hydrocraking the crude source is not much of a factor but cost to mfg as in percent through put is a economic deal. GPIII is up to 135 VI or so GPII 110 and GP1 95 or so. Next will be GTL (gas to liqiud) since the gas is now burned off it will be a cheaper way to go with VI >140 But agin how high is always bounced off of cost. If there is a market we will get it that is how GPII nad GPIII came about less VII and better PCMO's drove that train. Cost aside how high can a "mineral" oil go??? Do not know but there are syns out now that are in the 250 plus range. bruce bruce

 

[Audi Junkie]

Delo SAE 30 is a finished oil, but a monograde that has a VI of 125.

 

[bruce381]

Yeah but remember that the DI package will always bump the VI of the blend over the base oil alone. and I think ALL chevrons straight grade are GPII plus a GP1 bright stock for grades heavier than 30wt. Delo 30 would IMHO be a GPII all the way with a good oronite DI pack and some PPD and NO VII so very good HTHS and NO real shear loss. bruce

 

[Audi Junkie]

Any idea of the HT/HS? 3.5 would be nice.

 

[bruce381]

Not sure but using the LZ blend software and LZ DI package for a CI-4/SL oil you can get with chevron base stock. Vis 100 12.1 VI 121 HTHS 3.41 NO VII at all. Bruce

 

[Audi Junkie]

My bad, VI of 104. https://www.cbest.chevron.com/msdsServer/controller?module=com.chevron.lubes.msds.bus.BusPDSList®ion=NA&txtPDSNumber=DELO&directPDSLink=TRUE&isLoginPage=true&lbLanguage=e

 

[Curious Kid]

Thanks - interesting thus far. I remember reading VI of some AT oils being around 200, so I pondered why the limitations on MO? Is this VI value common for these oils? Does AT oil have any VII's - I would think not do to the long OCI and gearing, but what do I know? Thanks again!

 

[bruce381]

ATF has VII and the problem is both shear out of grade and sludge with high amounts. A PCMO can be made with VI over 200 try a 10/50 syn. bruce

 

[Blue99]

I've always considered the VI index of a base oil and a finished motor oil to be similar, yet different concepts. Yes, VI index does indicate the rate of change of viscosity to temperature for both. -The VI for a base oil is dependant on the hydrocarbon molecular structure with hydro-cracked & catalytic de-waxed oils, Grp II+ & III's, and the synthetics, having better temperature properties. -The VI index for a finished oil is generated by the blend of base oils and the viscosity related additives - pour point depressants, VI improvers, etc. This is why a 140-150 VI index number for a base oil is high, and a finished oil, such as Quaker State Winter Blend can have a VI index over 200.