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#4667944 - 02/16/18 03:03 PM viscosity index improvers-improvement?
frankbee3 Offline


Registered: 12/22/16
Posts: 34
Loc: New Hampshire
Hello,

I am wondering if any improvements have been made to VII's with respect to combustion chamber deposits.

I was reading an engineering manual of piston aircraft engines by Jon Schwaner, who mentioned the shearing of VII's but also mentioned that VII's have shown increased combustion chamber deposits due to oxidation and thermal decay. I have a Cessna 180 aircraft which has a Continental O-470 engine in it. In the winter, I used Aeroshell 15w50 semi-synthetic oil. In the summer, I prefer Aeroshell 50 weight oil to avoid shearing and combustion chamber deposits.

All of my reference materials are 20 years old or older. I had an article that was in an SAE publication where Shell Oil and Mercedes tested 10 wt, 10W30, and straight 30 weight oil were compared for cylinder wear rates. I seem to recall that the straight 30 weight oil showed the lowest wear rate in the cylinder wall and ring pack.

I am also wondering how to tell if synthetic oils have viscosity index improvers added, or not? I would expect a mineral based 10w30 motor oil to have a VII added to it. Is it likely that a synthetic based 10w30 oil would not have VII added?

When I lived in a very temperate climate, I used to use straight 30 weight oils in a VW Beetle air-cooled engine along with all the cars we had that specified 10w30 or 5w30 oil.
It is no longer practical to run straight weight oils where I live now.

I found the motor oil university on BITOG to be very helpful too.

Am I correct in my assumption that viscosity index improvers have gotten better over the years?
_________________________
1992 Toyota Pickup
2001 Mazda Miata
2003 Dodge Ram 2500 Cummins
2008 Subaru Outback
Cessna 180
Miscellaneous Yard tractors and lawn mowers

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#4667947 - 02/16/18 03:06 PM Have there been any improvements to VII's?
frankbee3 Offline


Registered: 12/22/16
Posts: 34
Loc: New Hampshire
Hello,

I am wondering if any improvements have been made to VII's with respect to combustion chamber deposits.

I was reading an engineering manual of piston aircraft engines by Jon Schwaner, who mentioned the shearing of VII's but also mentioned that VII's have shown increased combustion chamber deposits due to oxidation and thermal decay. I have a Cessna 180 aircraft which has a Continental O-470 engine in it. In the winter, I used Aeroshell 15w50 semi-synthetic oil. In the summer, I prefer Aeroshell 50 weight oil to avoid shearing and combustion chamber deposits.

All of my reference materials are 20 years old or older. I had an article that was in an SAE publication where Shell Oil and Mercedes tested 10 wt, 10W30, and straight 30 weight oil were compared for cylinder wear rates. I seem to recall that the straight 30 weight oil showed the lowest wear rate in the cylinder wall and ring pack.

I am also wondering how to tell if synthetic oils have viscosity index improvers added, or not? I would expect a mineral based 10w30 motor oil to have a VII added to it. Is it likely that a synthetic based 10w30 oil would not have VII added?

When I lived in a very temperate climate, I used to use straight 30 weight oils in a VW Beetle air-cooled engine along with all the cars we had that specified 10w30 or 5w30 oil.
It is no longer practical to run straight weight oils where I live now.

I found the motor oil university on BITOG to be very helpful too.

Am I correct in my assumption that viscosity index improvers have gotten better over the years?
_________________________
1992 Toyota Pickup
2001 Mazda Miata
2003 Dodge Ram 2500 Cummins
2008 Subaru Outback
Cessna 180
Miscellaneous Yard tractors and lawn mowers

Top
#4667987 - 02/16/18 03:41 PM Re: Have there been any improvements to VII's? [Re: frankbee3]
MotoTribologist Offline


Registered: 02/03/16
Posts: 562
Loc: NJ, USA
Yes there are improvements in the realm of VIIs. There are also all the old types still available. So it depends on what the formulators are choosing and what they are formulating for. Different applications might call for different VII types.

A multigrade oil is more than likely going to contain VII as part of the formula, regardless of whether it is synthetic or non-synthetic.

Specifically about combustion chamber deposits potential, I don't know. It's never been an issue with the formulas I've worked on, so I haven't looked at VII performance to address that specific concern. I would venture the guess that it was more of an issue in the past and likely not such a concern directly attributed to VIIs now, but someone may correct me on that if I'm wrong.


Edited by MotoTribologist (02/16/18 03:41 PM)
Edit Reason: Spelling

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#4668328 - 02/16/18 10:08 PM Re: Have there been any improvements to VII's? [Re: MotoTribologist]
frankbee3 Offline


Registered: 12/22/16
Posts: 34
Loc: New Hampshire
I suspected that VII's (VM's) must have improved over the last 25 years.

For aircraft, I still prefer straight weight oils in summer and only use multi-grade in winter with pre heat. On aircraft engines, I have seen a lot of valve guide wear, stuck or broken rings and stuck exhaust valves and the occasional stuck intake valve from combustion deposits.

For cars and my diesel pickup, I have started using synthetics for winter starts, but haven't bothered switching during summer.

It has just occurred to me that the entire collection of piston engine machinery that I have are not oil burners.
Growing up, I ended up owning a lot of clapped out cars and motorcycles that had poor maintenance by previous owners. I might not ever need to overhaul an engine in any of my cars again. It's a good thing since my overhaul tools were stolen years ago...

It seems as though the proportion of VM's in synthetic oils may be reduced compared to conventional oils? I am guessing that a 5w30 synthetic would have less VM's compared to a conventional 5W30, and the synthetic would be less prone to shear and oxidation at the very least.
_________________________
1992 Toyota Pickup
2001 Mazda Miata
2003 Dodge Ram 2500 Cummins
2008 Subaru Outback
Cessna 180
Miscellaneous Yard tractors and lawn mowers

Top
#4668341 - 02/16/18 10:30 PM Re: Have there been any improvements to VII's? [Re: frankbee3]
HondaBroMike Offline


Registered: 11/02/17
Posts: 312
Originally Posted By: frankbee3
I suspected that VII's (VM's) must have improved over the last 25 years.

For aircraft, I still prefer straight weight oils in summer and only use multi-grade in winter with pre heat. On aircraft engines, I have seen a lot of valve guide wear, stuck or broken rings and stuck exhaust valves and the occasional stuck intake valve from combustion deposits.

For cars and my diesel pickup, I have started using synthetics for winter starts, but haven't bothered switching during summer.

It has just occurred to me that the entire collection of piston engine machinery that I have are not oil burners.
Growing up, I ended up owning a lot of clapped out cars and motorcycles that had poor maintenance by previous owners. I might not ever need to overhaul an engine in any of my cars again. It's a good thing since my overhaul tools were stolen years ago...

It seems as though the proportion of VM's in synthetic oils may be reduced compared to conventional oils? I am guessing that a 5w30 synthetic would have less VM's compared to a conventional 5W30, and the synthetic would be less prone to shear and oxidation at the very least.


I remember there being an inverse relationship with moly and VIIs. The more moly, the less VIIS you needed. The 0w-20s do not shear, I know this much, I am running a car that calls for this oil that I am using right now in the 0w-20 weight. Doesn't burn a drop. I've had semi and full synthetic OTC oils like Mobil 1, Pennzoil snthetics and even semi synthetic 5w-20s all burn but this 0w-20, nothing. It's amazing what they put in these 0w-20s. It could be the engine design too, can't forget about that. "in conjunction with"


Edited by HondaBroMike (02/16/18 10:34 PM)
_________________________


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#4668410 - 02/17/18 01:23 AM Re: Have there been any improvements to VII's? [Re: frankbee3]
SonofJoe Offline


Registered: 07/23/16
Posts: 1052
Loc: Europe
If we're being honest, 'proper' VII development sort of stopped in the late 1970s.

In the beginning, there were PMAs; okay but hopelessly inefficient. Then we got amorphous OCPs; cheap, easy to make & moderately efficient. Then Exxon pushed high ethylene OCPs which were slightly more efficient but prone to low temperature gelling problems. Finally were had Dave St. Clair of Shell doing his pioneering work on HSD VII; highly efficient but complicated & expensive to make and prone to high temperature shear.

With regard to piston deposits (and especially diesel deposits) VII rubber loading is critical. All things being equal, the more rubber you have, the more deposits you'll get. I never got around to definitively checking but my gut feel was always that in terms of deposits, rubber is rubber is rubber regardless of whether it comes from PMA, OCP or HSD. You can of course mitigate the effects of VII on deposits with additives (especially Ashless Dispersants) but this in turn bring its own set of problems.

However the easiest way to reduce the amount of VII rubber in oil is (a) select the narrowest viscocity grade you can live with (b) formulate you oil with Group III, and preferably Group IV synthetic base oil. You could add to the list, formulate the oil to be viscometrically 'tight' (something the US is notoriously bad at!).

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#4668432 - 02/17/18 03:16 AM Re: Have there been any improvements to VII's? [Re: frankbee3]
FordCapriDriver Online   content


Registered: 10/22/15
Posts: 2388
Loc: Balearic Islands , Spain
There have been huge improvements to VII's since the 70s / 80s, modern oils use less VII's than before and the VII's have been updated a lot so they don't shear anywhere near as easily and don't form deposits.
_________________________
1975 Ford Capri II Ghia 3000 V6, - Valvoline VR1 20W-50
1988 Ford Escort MkIV 1.6 Xr3i Cabrio, - Shell Rimula R4X 15W-40 HDEO.

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#4668437 - 02/17/18 03:59 AM Re: Have there been any improvements to VII's? [Re: FordCapriDriver]
SonofJoe Offline


Registered: 07/23/16
Posts: 1052
Loc: Europe
Originally Posted By: FordCapriDriver
There have been huge improvements to VII's since the 70s / 80s, modern oils use less VII's than before and the VII's have been updated a lot so they don't shear anywhere near as easily and don't form deposits.


I think you're getting a few things confused.

By tradition, the US has always used high (50-ish) SSI VIIs (these are the ones that shear) because they are cheap and aid fuel economy. Europe on the other hand has always used low (22-ish) SSI VIIs which shear much less. VIIs, regardless of chemistry, have only tended to come in three SSI favours; 22, 35 & 50. There are a few very low SSI HSD VIIs but these tend to be eye-wateringly expensive and are only found in ultra top tier oils.

Modern oils, for a given base stock & viscocity grade, contain more or less the same amount VII as they did in the 70s & 80s. Modern oils tend to contain more DI but the bulk of DI componentry has a negligible impact on how much VII polymer you need.

Go back in time and you will find plenty of 1980s patents referring to Texaco TLA-347, one of the original amorphous OCP VIIs. Whilst this additive died a long time ago (along with Texaco Chemicals), you would be hard pressed to differentiate it from Lubrizol 7077; today's biggest selling global VII.

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#4668702 - 02/17/18 12:28 PM Re: Have there been any improvements to VII's? [Re: frankbee3]
BrocLuno Offline


Registered: 09/06/15
Posts: 5528
Loc: Kalifornia Kollective
And all that is why I like Chevron Delo 400 15W-30 SD (severe duty). It's still a multi, but with a pretty narrow spread smile It's easy enough to start anywhere outside the "rust belt" and holds up well smile

Or, run SAE 30 HD and not worry at all about VII's beer

Or, run 0W-40 synthetic and pay the price frown
_________________________
Formerly in marine engineering. In an earlier life I owned my own petroleum tank truck, and hauled for the majors and independent's.

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#4668959 - 02/17/18 05:41 PM Re: Have there been any improvements to VII's? [Re: BrocLuno]
frankbee3 Offline


Registered: 12/22/16
Posts: 34
Loc: New Hampshire
Thanks for the suggestion of the Chevron Delo 400 15w30 SD. I had never even heard of it. Will check it out.

I still have two OCI's worth of Rotella T 30 weight to use up, but I will only use that in the summer.

BrocLuno, where in Kali are you? Wife and I moved out of San Diego almost 3 years ago. I was shocked at the fuel prices when I visited San Diego last month. Gasoline and diesel are about $.80 to a $1 more per gallon in California. Jerry Brown and the legislature need to go on a fiscal crash diet.

I have found it difficult to find research papers on the effects of VM's or VII's. I used to have access to SAE papers 20 years or more ago. A subscription is prohibitively expensive for me.

I appreciate all of your responses. Lot's of knowledge on BITOG.
_________________________
1992 Toyota Pickup
2001 Mazda Miata
2003 Dodge Ram 2500 Cummins
2008 Subaru Outback
Cessna 180
Miscellaneous Yard tractors and lawn mowers

Top
#4669229 - 02/17/18 11:49 PM Re: Have there been any improvements to VII's? [Re: frankbee3]
BrocLuno Offline


Registered: 09/06/15
Posts: 5528
Loc: Kalifornia Kollective
Older studies show that straight grade oils are better at cylinder wall wear. Even though they are older studies, since the VII chemistry has not changed all that much, I think it's still valid ...



Delo 400 15W-30 is available on Amazon most of the time. Just order enough to get free shipping. Or. drop by your local Chevron products distributor and see what they can do on pricing ...

I'm in Napa Valley about 70 miles N of SF. Still close enough to get bad traffic and pay Bay Area prices, but far enough out to actually live in the County and feel like the country. Grew up in the Santa Cruz mtns racing around the back country roads before "silicon valley" happened.

Have worked in SD a few times. Nice area, but going crazy like the rest of civilian Cali.

I say civilian because most folks don't know that over 50% of Cali is owned by the Gov't. USFS, BLM, USAF, US Army and US Navy/Marines all own huge tracts of the state. Not to mention US Bureau of Reclamation ...

If just 10% of that land were available for development, it would drop housing prices by 1/3. Would upset the real estate interests, but make working folks happy smile


Edited by BrocLuno (02/17/18 11:52 PM)
_________________________
Formerly in marine engineering. In an earlier life I owned my own petroleum tank truck, and hauled for the majors and independent's.

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#4669863 - 02/18/18 02:56 PM Re: Have there been any improvements to VII's? [Re: BrocLuno]
frankbee3 Offline


Registered: 12/22/16
Posts: 34
Loc: New Hampshire
That cylinder wear chart looks familiar. There was a Mercedes/Shell paper about 20-25 years ago that showed similar results, but delved into other details too. I hope to find it sometime soon...

Thanks for posting that.

I have a sister that lives up in your area. She's in Cloverdale. Nice area.
_________________________
1992 Toyota Pickup
2001 Mazda Miata
2003 Dodge Ram 2500 Cummins
2008 Subaru Outback
Cessna 180
Miscellaneous Yard tractors and lawn mowers

Top
#4670925 - 02/19/18 01:47 PM Re: Have there been any improvements to VII's? [Re: frankbee3]
PeterPolyol Offline


Registered: 03/06/16
Posts: 1345
Loc: toronto
Originally Posted By: frankbee3
There was a Mercedes/Shell paper about 20-25 years ago that showed similar results, but delved into other details too.


Yeah, that's the one. It even says OM616. Just look at that SAE 30

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