# viscosity vs burning/using up oil



## pturner67 (Dec 27, 2002)

I've seen some people in here discussing issues about their car burning or using up oil...having to top off, etc
was talking with a guy I work with...he has a new Porsche 911...it comes with M1 0w40...he said his oil light came on and he took it to the Porsche dealership...oil was low...Porsche said that their cars burn through the M1 0w40 very easily and that he might want to go with something thicker like 5w40 or even 10w40 (he said those weights are approved with Porsche)
I have a new Passat 2.0T TSI and my car didn't go through any oil at all using Castrol Syntec 5w40...am now using M1 0w40 for the last 1500 miles and haven't checked the level since I changed over...might just look into it tomorrow morning
my question is: does thinner oil like M1 0w40 really get used up faster than something like 5w40 or is it just a symptom of the car itself? And is there REALLY a big difference in oil brands or is synthetic oil pretty much the same despite the marketing campaigns?


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## meb58 (Jun 22, 2009)

hopefully others will chime in as well. 
Viscosity plays a role but so do the individual oil characterisitcs...garden variety M1 5W30 is not the same as M1 5W40 Turbo Diesel Truck - the later being a much better oil for our applications.
An oil's shear resistance is but one criteria but perhaps more important is its flash point. An oil with a high flash point is more prone to burning off. 
My daughter drives a 2,000 2.0 golf with 160K miles on it. She has been using a cheap bargin supermarket brand 10W40 oil and was going thru a quart of oil about every 4 days. I changed the oil and filter and put in M1 5W40 turbo Deisel Truck oil and I just added a 1/3 quart after 1,600 miles of driving - about 4 1/2 weeks of driving. That's the only difference.
So, a slightly lighter viscosity oil but a much better oil. My wide's 07 Passat gets Redline...she drives about 7,500 miles a year.


_Modified by meb58 at 12:49 PM 9-29-2009_


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## pturner67 (Dec 27, 2002)

*Re: (meb58)*


_Quote, originally posted by *meb58* »_but perhaps more important is its flash point. An oil with a high flash point is more prone to burning off.

interesting...here is what I have read about that
"Flash point is the temperature at which an oil gives off vapors that can be ignited with a flame held over the oil. The lower the flash point the greater tendancy for the oil to suffer vaporization loss at high temperatures and to burn off on hot cylinder walls and pistons. The flash point can be an indicator of the quality of the base stock used. The higher the flash point the better. 400 F is the minimum to prevent possible high consumption. Flash point is in degrees F."


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## wannagofast (May 25, 2008)

*Re: (pturner67)*

The Castrol and Mobil oils your talking about have the same starting viscositys when the oil is at operating temps which is most of the time. As more miles are put on the oil one may end up with a lower viscosity than the other due to shear. Castrol has a higher starting weight only when the oil is cold 0W vs. 5W. Oil evaporation loss is minimized with a higher flashpoint and a low NOACK volatility score. All oils are not the same and really differ in the additive packs each company uses.


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## animaniac (May 26, 2005)

*Re: (wannagofast)*

Porsches are reowned for burning oil, stops piston ring wear.
You havent checked the oil level in 1500 miles







thats risky, vw states upto 1 litre per 600 mile can be burned and thats normal to them.


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## pturner67 (Dec 27, 2002)

*Re: (animaniac)*


_Quote, originally posted by *animaniac* »_
You havent checked the oil level in 1500 miles







thats risky, vw states upto 1 litre per 600 mile can be burned and thats normal to them.

just checked it cold this morning...clean oil and it's like it isn't missing a drop


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## saaber2 (Jul 15, 2008)

*Re: (wannagofast)*


_Quote, originally posted by *wannagofast* »_The Castrol and Mobil oils your talking about have the same starting viscositys when the oil is at operating temps which is most of the time. As more miles are put on the oil one may end up with a lower viscosity than the other due to shear. Castrol has a higher starting weight only when the oil is cold 0W vs. 5W. Oil evaporation loss is minimized with a higher flashpoint and a low NOACK volatility score. All oils are not the same and really differ in the additive packs each company uses.

+1 
I would add that base oils can vary dramatically from brand to brand and in specific formulations within a brand. POE basestocks for example provide more shear stability, better lubricity, higher flashpoint, and lower volatility than PAO basestocks in general but it depends on the specific formulation. These ester basestocks are much more expensive. Even high end POE oils such as redline are a mix of base oils. Oils such as Motul has high end stuff that has a larger % of ester base oils while lower end oils have less. This is reflected in their performance. Similarly M1 TDT 5w40 is thought to contain more esters vs m1 0W40, hence it's higher shear stability. Only the oil companies know for sure the exact mix of base oils.


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## Mr Roo (Aug 8, 2006)

*Re: (saaber2)*

I have same question but dealing with differnt car. My wife has a trooper and is starting to burn oil as they are well known to do. I was told by many to move to turbo diesel oil, but was scared to do so. I have always used synth oil in her truck. There is no issue with going over to diesel other than the fact that it resists oil burning?


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## saaber2 (Jul 15, 2008)

*Re: (Mr Roo)*

Depends what oil you are talking about. Many diesel oils are "mixed fleet" which means u can use them in gas engines. M1 TDT 5W40 is an example. Have you tried auto-rx to get rid of the oil burning? It worked on my volvo. If the burning is due to clogged ring packs it will likely fix the problem. If it is due to worn out rings or other wear, it won't.


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## animaniac (May 26, 2005)

*Re: (saaber2)*


_Quote, originally posted by *saaber2* »_Depends what oil you are talking about. Many diesel oils are "mixed fleet" which means u can use them in gas engines. M1 TDT 5W40 is an example. Have you tried auto-rx to get rid of the oil burning? It worked on my volvo. If the burning is due to clogged ring packs it will likely fix the problem. If it is due to worn out rings or other wear, it won't.

True, the amount of s*** which gets left in the cylinders by the combustion process is unreal, just shows how crap the fuel is.


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## 1.8Tquattro (Aug 13, 2006)

*Re: (animaniac)*


_Quote, originally posted by *animaniac* »_Porsches are reowned for burning oil, stops piston ring wear.
You havent checked the oil level in 1500 miles







thats risky, vw states upto 1 litre per 600 mile can be burned and thats normal to them.

I checked my oil yesterday and it had been over 3000 miles. I usually never check it between oil changes. 
I checked it regularly when I first bought the car, but it never used any oil so I started checking it less and less, and pretty much never check it now. 
0-W40 M1 BTW.


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## animaniac (May 26, 2005)

*Re: (1.8Tquattro)*

Alot depends on miles and engine operating conditions, but at the bear minimum give it a check once a week, peace of mind for just a few seconds of your time, and while your checking the oil you can check other parts of the engine bay and engine, you may spot a cracked coolent hose or a loose bolt which could leave you stranded.


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## rickjaguar (Apr 23, 2009)

*Re: viscosity vs burning/using up oil (pturner67)*


_Quote, originally posted by *pturner67* »_
my question is: does thinner oil like M1 0w40 really get used up faster than something like 5w40 or is it just a symptom of the car itself? And is there REALLY a big difference in oil brands or is synthetic oil pretty much the same despite the marketing campaigns?

Not all oils are equal. IMO Mobil and Castrol are the most basic of formulas that might meet the minimum requirements. 
The FSI is more notorious for burning than the TSI from what i've learned so far.. but still. For all the potential headaches this engine might incur it made me very keen to find a higher quality oil. The price is worth it (for performance.)


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## vdubGLI09 (Aug 21, 2009)

ptuner67 - Back to your original question. I personally don't believe what the dealership is correct with what they've told your friend. Technically, 0w-40, 5w-40 and 10w-40 are all the same weight oils at operating temperatures (in this case a 40 weight). 
The "W" following the first visocity grade (lets use the case of 5w vs. 10w) indicates that the oil is suitable for winter use. The visocity grade preceding the "W" is just the viscosity grade of the oil when measured at the appropriate low temperatures based on the SAE viscosity classification system. 
The lower the value of the first viscosity grade, the better the pumpability and crankability of that oil at low temperatures. 
Example: in order to be classified as a 5w oil under the SAE system, the maximum cranking viscosity of the oil can not exceed 6,600 cP @ -30 (degree celius) and the maximum pumping viscosity can not exceed 60,000 cP @ -35. For 10w you have a maximum cranking visc. of 7,000 cP @ -25 & a maximum pumping visc. of 60,000 cP @ -30. In layman terms, the 5w is 400cP thinner @ a lower temperature than the 10w.



_Modified by vdubGLI09 at 3:30 AM 10-9-2009_


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## knagy19 (Oct 11, 2009)

*Re: 2007 Rabbit using oil*

I am having a problem with my 2007 Rabbit using oil 2.5l 
the oil hase been changed @ 4000 mi inc. using normal 5-30 at the local oil Pensoil oil change regular 5-30 
never burned a drop of oil 
Then I decided to change the oil myself and read the manual (WOW) and noticed the vw502 oil spec. 
So I looked around for a oil that met the 502 found Lucas oil 5-30 syn. it even says on the label meets VW502 
I have 2000 miles on this and have gone thru over 1 quart!!
My two thoughts are 
1) change to mobil 1 0-40 
2) go back to pensoil 5-30
Then see if I keep using oil -- 
I have 29000 mi on the car?
need some help and ideas
Thanks


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