Pennzoil PureBase 5w20 vs Pennzoil Synthetic 5w20

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Well, my 3000 mile experiment with Pennzoil 5w20 will be coming to an end very soon, and thanks to the generosity of Johnny, our resident Pennzoil guy, the next 3000 miles will see Pennzoil synthetic 5w20 in my Chrysler. So, we are going to get a direct comparison between these two oils from an engine that is spec'd to run on 10w30. Look at the specs for the regular Penn 5w20 and synthetic. The regular 5w20 beats the syn 5w20 in several important specs, and it's a virtual draw in the others. Molakule or Terry, would you like to offer an opinion as to why the regular 5w20 would have a lower pour point than the all-Group III synthetic 5w20?
code:
			Conventional 5w20	Synthetic 5w20

Flash Point, °C(°F) 		229(445)	Not listed
Pour Point, °C(°F)  		-45     	-42

Viscosity
@ 40°C, cSt 			48.0		46.72
@ 100°C, cSt 			8.6		8.8

Viscosity Index 		158		171
HT/HS 				2.65		2.70

 

MolaKule

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Sure. Statistically speaking, not much of a difference. The most obvious thing to me would be that the dino version starts off with a much lower viscosity base oil as evidenced by the 100 C viscosity, say a 2-4 cSt oil (in order to arrive at a descent 40 C viscosity), and then they blend in other viscosities, and add more VII for the target visocsity as indicated by the 40 C. In the synthetic version, they most likely started with a 6 cSt base oil of wide VI. Also notice that the synthetic version has a better 40 C viscosity due to the wider VI of the starting base oil used, and most likely little if any VII's. Addendum: If they are using any VII's, it's most likely the improved "Star Molecule" ultra-shear-stable VII. [ May 29, 2004, 05:29 PM: Message edited by: MolaKule ]
 

G-MAN

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quote:
Originally posted by MolaKule: In the synthetic version, they most likely started with a 6 cSt base oil of wide VI. Also notice that the synthetic version has a better 40 C viscosity ...
I'm not sure I follow you here. The synthetic 5w20, with a 40 C vis of 46.72, has a LOWER 40 C vis than the conventional 5w20, which is 48.0. How is the lower vis "better?" Also, couldn't the lower VI of the conventional 5w20 coupled with the 40 C vis of 48 (vs 46.2 for the syn) indicate less VI improver in the conventional? I have no doubt that the base oil blend in the conventional has an inherent VI of around 120, and the base oil blend in the synthetic has an inherent VI of around 140. If that is true, would the finished VIs of 158 and 171, respectively, indicate roughly the same level of VI improver used in both oils? [ May 29, 2004, 05:59 PM: Message edited by: G-Man II ]
 

MolaKule

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I wasn't saying one is necessarily better than the other. Just commenting on the blending technology "most likely" used.
quote:
I'm not sure I follow you here. The synthetic 5w20, with a 40 C vis of 46.72, has a LOWER 40 C vis than the conventional 5w20, which is 48.0. How is the lower vis "better."
It might be better in terms of cold start oil flow.
quote:
Also, couldn't the lower VI of the conventional 5w20 coupled with the 40 C vis of 48 (vs 46.2 for the syn) indicate less VI improver in the conventional?
Not likely. Again, I was simply commenting on the most likely blending scenario. Again, with dinos, and for low viscosity oils, you start off with a very light oil of low(er) VI and work up the viscosity with heavier oils and VII's.
quote:
I have no doubt that the base oil blend in the conventional has an inherent VI of around 120, and the base oil blend in the synthetic has an inherent VI of around 140. If that is true, would the finished VIs of 158 and 171, respectively, indicate roughly the same level of VI improver used in both oils?
Again not likely. Less amounts are VII are needed when you have wider VI base oil(s). Blending economics would also dictate that if the base oil can do the job at less expense than the additive package, then use more of the base oil. Even synthetic base oils are less expensive per ounce than any single additive.
 
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the only difference i see is in the viscosity index, everything else is so close that they should be considered equal. buying one oil over another because of a few degrees of tempature difference, or an hths of .5 difference is moot.
 

MolaKule

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quote:
Statistically speaking, not much of a difference.
I wish Pennzoil would bring back the Peformax. It had the best price/performance of ANY synthetic oil, because of its full synthetic base and set of Friction Modifiers. I suspect they discontinued it because of component costs. [ May 30, 2004, 12:40 PM: Message edited by: MolaKule ]
 
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G-Man II, Molakule is the chemist and I agree with what he has shared, I will add the fact that as soon as we get 5000 miles of use the pour point would degrade significantly on GRPII oil vs. the non syn Grp III syn ! [LOL!] VI index gives us a relative and comparative guage of what the clean oils can do,...... oxidize and shear those oils and the oils with less added VII will "generally" be more consistant in remaining at design vis measurements. The final formulation ( sum) is more important than looking at the parts alone. The differences you point to as "better" in the conventional based Pennzoil is not really significant at all by what you are showing here. If published, pumpability should be significantly better with the Group III and if not , may be just a way to lower costs and use less adds, another comment Mola made. Case in point; Schaeffers while being a lower cost blend performs as well or better than many high end syns because they took the time to procure and properly MATCH the parts (components) of the final result. Thats why that oil formula is still one of my favorites because it performs well in used oil analysis. Not JUST looks good on a spec sheet. The reformulation of Scheaffers will be interesting to see with GF4/SM knocking at the door. In the early 70's one thing that really hurt the early M1 formulas ( 5w-20) was that they used a really good PAO base and relied too heavily on that while, IMHO, under added the finished product allowing valve train wear that hurt the brand reputation. See Pabs I comment on other BRANDS warts !! [Freak] Good questions and I hope I illuminate a little analysis light for you. [ May 31, 2004, 12:06 PM: Message edited by: Terry ]
 

G-MAN

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quote:
Originally posted by MolaKule: I wish Pennzoil would bring back the Peformax. It had the best price/performance of ANY synthetic oil, because of its full synthetic base and set of Friction Modifiers.
Well, if we assume it's the same chemists who developed Pennzoil's current Group III based synthetics who developed Performax, maybe Pennzoil's current sythetics will turn out to be the best price/performance of any Group III synthetic. [Big Grin] What was in Performax that made it such a great oil? (I remember reading that Pennzoil got their PAO from Mobil, BTW.)
 
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