Valvoline All Climate has the following VIs:
5w30: 162
10w30: 135
10w40: 148
20w50: 125

Bosch Automotive Handbook says the higher the VI number, the more resistant to changes with temperature. So one initially might think the higher VI number is good, but we know that a 5w30 and a 10w40 are much higher in viscosity index improver polymers than are a 10w30 or 20w50. So, while a high natural viscosity index number may be better (typically synthetic oils have a higher VI number), I think that a higher VI number also may indicate more viscosity index improver polymers were added to the base oil (not good), so really the lower the VI number seems better (of course one must apply this logic within similar type oils, not between cheap dino and a synthetic).

Two things determine the amount of polymers needed: the weight of the base oil (higher is better, 20w is better than 10w) and the spread (smaller is better, though a greater spread is ok with a heavier base oil, such that 20w50 with a 30 spread is about as good as 10w30 with a 20 spread). Now I understand the front number or (w number) is the base oil and polymers are added to get the back number (at least with dino oils).

So what am I getting at? I can look up the 100C viscosity for most multigrade oils, but I also am interested in how robust the base oil is at that temp. When comparing two similar dinos of 10w30 and say both have 100C viscosities of, say, 10.5, which is better? Presumably the one with the lower viscosity index as that would imply the 10w base oil is higher in the 10w range (which goes from 4.1 to 5.6 at 100C) than for the oil with the higher viscosity index and so I would prefer the one that is higher in the base oil viscosity range since it should have less viscosity index improvers to get to the 10.5 viscosity at 100C. I know they do list low temp viscosity but they vary the temperature across the range of SAE W categories, which makes it hard to evaluate. Besides, I think the 100C viscosity of the base oil is a better predictor of how the oil with its viscosity improver additives will hold up.

 

VI is one of those specs from product data sheets that may be interesting, but have little relevance today. Specific gravity and color are also there, but who cares? I think these are relics from the distant past when motor oils pretty much came right out of the distllation column and there were huge differences in properties depending upon the source of the crude. Pennsylvania oils had a high VI and specific gravity, but also high pour point vs Gulf coast oils that had a low VI and specific gravity but low pour point.

VI of the base oil matters a lot, but you cannot tell on the finished product if the high VI is from superior base oil or from a lot of VII additive, which I think is your point.

I look at the flash point as an indicator of base oil quality. I think you will find, on average, that for a given viscosity at 100C, a higher flash point roughly corresponds to lower volatility and oxidation due to less VII and a more robust base oil, dino or syn.

Jim

 

I agree with Jim. The only way to know for sure to get an oil that has a high base oil V.I. vs one that uses V.I. index improver's, is to select a brand that you know uses a hydrotreating process to produce their base oils.

 

I'll third that.

Also, VI improvers in and of themselves are not particularly bad. The problem with them is they eventually shear causing viscosity loss, which of course is not good.

The way to combat this is use an oil with high quality base stocks and change it when you should.

 

Thanks, I figured it was the impossible question. I talked to a Chevron tech today and am thinking of going over to Chevron Delo in all my vehicles. The Chevron tech told me that between a 10w30 and a 10w40, the 10w40 would have a heavier base oil, largely to minimize the amount of VI improvers needed to get the 40. I was rather dissappointed to find out Valvoline actually marketed a teflon engine treatement (TM8 as advertized in mid 90s Hot Rod magazine) and later found where the FTC got after them for false advertizing with TM8. When I e-mailed them about it they just said, we don't produce that product anymore.

 

The correct definition of Viscosity Index is a commonly used measure of a fluids change of viscosity with temperature. The higher the Viscosity Index the smaller the relative change in viscosity with temperature.
TP, most of the techs that you will get to talk to from Chevron and Mobil/Exxon are not in the USA and are reading you canned answers. I wouldn't go run to the bank with any info that they give you as it usually is dated. Beware any MSDS or data sheet that is published on the internet or given by phone as these are usually also dated. We have a girl at work that does nothing but updates our files with MSDS and data sheets and she is behind. Case in point, Chevron Supreme in 5w-20 may not show on their "current" info as having any moly. It is in their 4th formulation since June and it "currently has 250 ppm's prox. Seems all the motor oils are going thru a transition now looking for that magic combination.

 

Jimandmandy: I just re-read your post and it appears to be excellent advice. I had heard that info about Pennsylvania vs Gulf Coast oils before and actually thought I had heard that Valvoline uses more of the Gulf Coast oils. The Valvoline Maxlife seems to be pretty good oil and appears to have a good flash point too (230C on 10w30 for a 13.5 cST at 100C). Also, based on your advice, it dosen't matter to me anymore that they did not publish VI on the Maxlife data sheet. Only thing, the DELO has about 50% more zinc and phosporus than the Maxlife. Might be worth the switch for that.

Flash: Right, some of the data sheets are pretty old and some of the phone reps are pretty lame. The Chevron rep told me they use group II base oil, which is more than I could get from Valvoline (several tries always netted a transfer to a specialist who was away from the phone). I recently sent the same basic question to Valvoline Europe and Valvoline here and got a much more informative response from the European rep. Also the European response did not put the legal disclamer at the bottom as did the US rep. I don't think Valvoline is answering my emails anymore after I got on them for their weak response about the TM8 (see my message above).

Anyway, I put this post in hoping to learn something and get over some frustrations and the responses were quite informative. Horsepuller, I will have to check out that hydroprocessing too. Oppy, good point and note that todays VI improvers should be a lot better than the ones that gave so much trouble 30-40 years ago.

Thanks all.

 

Paul, if you want to read up some more on hydroprocessed oil, check out this old thread Each company has their own term for it. Like ISO-SYN or Purebase.

FWIW, the best response to my user's questions have come from Pennzoil. I've recieved real hand signed letters outlining responses to my queries.

Scott

 

Great thread Horsepuller. I had to bookmark it to do a little bit at a time. The article "The Evolution of Base Oil Techhnology" is also available at www.Noria.com in their Machinery Lubrication magazine in three parts (March, May, and Sept 2003). The Chevron site is pretty good too. I found a number of articles from Lubes'N'Greases magazine there. In fact, one of them clarified the hydrocracking:

"Basestock manufacturing is shifting from processing schemes based on solvent-refining and solvent-dewaxing to hydrocracking and wax isomerization. Many know this shift as a move from Group I to Group II basestocks." (published by the Independent Lubricant Manufacturers Association's "Compoundings," March 2001)

More interesting stuff from that article:

"Although Group II basestocks have been in the North American market for close to 15 years ... there were only two producers in North America. Chevron and Petro-Canada. This changed, however, when Excel Paralubes came on stream in 1997."

"... such companies as Pennzoil-Quaker State, Eqauilon, Castrol, Valvoline, and other marketers with relatively large shares of the PCMO market are in need of Group II and II+ basestocks."

I lined up some 10w30 oils by flash point as jimandmandy suggested (some of the data may be dated, but is current on the websites; also real values vary from the tech sheets). They are listed by flash point (C) and viscosity (100C in cSt):

232/10.8 Chevron Supreme
231/10.7 Valvoline Durablend
230/10.5 Valvoline Maxlife
228/10.4 Exxon Superflow
216/10.5 Valvoline All Climate

These oils all look about the same, but for lowly All Climate, which also came out well below the bottom on 5w30 and 10w40 line ups (which I can post if anyone wants to see them).

 

You guys are making my head hurt!

-Matt

 

I lined up various grades (5w30 thru 20w50) of Valvoline Maxlife, Durablend, and AllClimate; Chevron Supreme; Citgo Superguard and Ultralife; two Chevron Delo multigrades, and Exxon Superflow in order of flash point, which ranged from 206 to 258. The highest was 258 C for Chevron Supreme 20W50 (the next best 20w50 being 246). The highest 10W40 was Valvoline Maxlife at 242 (the next best being 235). Highest 10w30 was Citgo Superguard at 233 (several in the lower 230s but with higher viscosities). Valvoline Durablend 5w30 was way up the list at 238, which I suspect may be in error as the 10w30 was only 231. Valvoline faired well, except for All Climate which was near the bottom of the list for 5w30 (206), 10w30 (216), 10w40 (216) and was the lowest 20w50 at 230. Bottom line, it seems that Valvoline All Climate is not very good. All the Chevron Supremes were high on the list. Valvoline Maxlife rated pretty good except the 5w30 which was 221. Citgo Ultralife was fairly low (both 10w30 and 10w40) at 224, but they do have higher than typical viscosities for these grades. The Chevron Delo did not come out that high with 15w40 at 230. I would have expected a higher number with a 15w40 as the 15 should be more robust than a 10w, but the Valvoline Durablend 15w40 was low also at 232. While the viscosity is lower, the Valvoline Maxlife at a 242 C flash point seems a better way to go than either of these 15w40s, especially in colder weather. The main advantage of Delo would be higher zinc and phosphorus anti wear additives of the HDMO. OK, now that I have everybody's heads spinning even more, I'll quit--for now.

 

Whats the difference in Exxon Superflo(Esso Superflo years ago) and Mobil 10W-30? The Price?

 

If you pull up the respective technical information sheets from the websites you may find very little difference. I was looking at BP oil tech data sheets and it looked very familiar. Turns out the BP is very similar to Valvoline. Some minor variations is certain parameters. May be same oil with slight difference in certain additives. Probably the same situation between Chevron and Havoline (definitely saw this with these two companies high mileage oils).