2006 Audi A8 4.2 0W40 OR 5W40 OIL?

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337
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Chicago
Hey guys i just bought a 2006 Audi A8 4.2 with 129k miles and im wondering would 5w40 fully synthetic oil be ok to use? The previous owner used 0w40 but i got Castrol EDGE 5W-40 Advanced Full Synthetic Motor Oil with a Audi oem oil filter. I live in Chicago and temps now are between 20s-40s. I just thought 0w40 is a bit thin considering the miles plus i think Audi calls for 5w40. I wont be driving the car much in winter but in spring n summer more often so thats why i was thinking to put 5w-40.
 
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39,615
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0W-40 is actually a better oil and not "thin," but Edge 5W-40 will be fine. Edge 0W-40 is currently on sale at Amazon (and Walmart) for $19 per jug.
 
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90
Location
NJ
You are out of warranty so take this as it is but any oil that meets the spec should be fine. I have a 2001 S4 and had a 2004 A4 1.8t. Both called for 502.00/505.00. Most of the approved oils were 0W-40 and 5W-40 but there were a few that were 0W-30. A lot of people were using Rotella T6 5W-40 with good results. I even ran it once or twice. I also run Amsoil EFM and AFL and Mobil 1 0W-40. I also ran Total something or other 0W-30 that met the spec.
 
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15,120
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As usual with this type of question it isn't at all about the grade, it is about the approval. Use an oil with the correct Audi approval and ignore the grade unless your expected starting temperatures are far below 0F (then pick an appropriate winter rating). With Audi approvals grade is irrelevant since the oil must meet a minimum HTHS. And again as usual with this type of question, 0W-40 is not thinner than 5W-40 unless it is -40F. At operating temperature and nearly everywhere else in between they are the same. So what Audi approval is required for your engine?
 
Originally Posted by boostedtsiawd
I just thought 0w40 is a bit thin considering the miles plus i think Audi calls for 5w40.
To help the OP get a feel about what is happening at lower temperatures, I have this graph showing what happens to the kinematic viscosity as the temperatures drop. There is nothing thin about a 0W40 oil. It would still be over 10 times thicker at 0 degrees C than it's viscosity at an operating temperature of 100 C. This graph only goes down to 0 C. While I don't have a 0w40 shown, have a look at the 5W30. I agree with Mr. Kschachn, the difference between 0W40 and 5W40 would be negligible until you got down to -40 C and the kinematic viscosities were above 6000 cSt. However, it should be noted that some manufacturers are asking for 0W40 for year round use regardless of the area or ambient temperature. They aren't doing it because they expect you to be in a -40 C ambient temp. See how the lines converge at 100 C. They aren't actually identical. They would range from approx 8 to 14 CSt which is the difference between an xw20 and a xw40 motor oil at 100 C. Now look at the huge differences between a 15W and a 5W at low temps. You can scale in a 0W just below the 5W line. smile

Kinematic Viscosity vs Temperature.PNG
 
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And here is an example of a 5W40 and a 0W40 plotted together, but they aren't the same manufacturer. Although there is a difference in the kinematic viscosity at 0 C, it isn't large. Not sure what year these products were . At -40 C, all these kinematic viscosities would be over 6000 cSt.

0W40 vs 5w40.PNG
 
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6,856
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California
It doesn't matter - M1 0W-40FS, Edge 0W-40/5W-40, Rotella 5W-40 or any Euro-speced A3/B4 with VW 50x certs works. My vote is for the 0W-40, it will help with those Chicago mornings when you account for windchill.
 

boostedtsiawd

Thread starter
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337
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Chicago
I hope 5w40 gonna be ok i was told to change the oil every 10k miles and i know i wont put 10k miles until probably the middle of summer or end of it so that is why i rather have 5w40 because 5w is good in warmer weather.
 
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Originally Posted by boostedtsiawd
I hope 5w40 gonna be ok i was told to change the oil every 10k miles and i know i wont put 10k miles until probably the middle of summer or end of it so that is why i rather have 5w40 because 5w is good in warmer weather.
No clue what you're saying there. Whether it is a 0W-40 or a 5W-40 won't make a bit of difference in "warmer weather." And once more, in this instance it isn't about the grade it's about the approval. Do you even know what approval is required for your engine?
 
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Richmond, VA area
Likely VW 502 00 approval required - I'd take the 0W40 for your colder "W" temps....plus it uses a more "synthetic" base than the 5W variants to get that 0W rating.
 
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boostedtsiawd

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Chicago
Originally Posted by kschachn
Originally Posted by boostedtsiawd
I hope 5w40 gonna be ok i was told to change the oil every 10k miles and i know i wont put 10k miles until probably the middle of summer or end of it so that is why i rather have 5w40 because 5w is good in warmer weather.
No clue what you're saying there. Whether it is a 0W-40 or a 5W-40 won't make a bit of difference in "warmer weather." And once more, in this instance it isn't about the grade it's about the approval. Do you even know what approval is required for your engine?
yes it says Castrol Edge 5w40 MEETS OR EXCEEDS INDUSTRY STANDARDS: VW 502 00 / 505 00
 
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15,120
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Originally Posted by boostedtsiawd
yes it says Castrol Edge 5w40 MEETS OR EXCEEDS INDUSTRY STANDARDS: VW 502 00 / 505 00
Then find the cheapest oil at Walmart which has actual 502 00 approval, regardless of grade. Grade is irrelevant. Most likely Castrol or Mobil 1 0W-40 at $25/5 quarts unless the Mobil 1 is on rebate.
 
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Colorado Springs
Originally Posted by boostedtsiawd
I hope 5w40 gonna be ok i was told to change the oil every 10k miles and i know i wont put 10k miles until probably the middle of summer or end of it so that is why i rather have 5w40 because 5w is good in warmer weather.
5W is not better in warmer weather. That does not have anything to do with warmer weather. In practical application, 5W40 is product step below 0W40. 0W40 carries MB229.5 approval and 5W40 does not (yet at least). MB229.5 is more stringent approval than VW 502.00 that you car calls for. xW or XXW are designations that determine cold performance. They do not indicate under any circumstances performance in warm weather. Actually, premier Castrol product is Edge 0W30, which is suitable for your car but it is $62 for 6qt on Amazon.
 

boostedtsiawd

Thread starter
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337
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Chicago
Originally Posted by edyvw
Originally Posted by boostedtsiawd
I hope 5w40 gonna be ok i was told to change the oil every 10k miles and i know i wont put 10k miles until probably the middle of summer or end of it so that is why i rather have 5w40 because 5w is good in warmer weather.
5W is not better in warmer weather. That does not have anything to do with warmer weather. In practical application, 5W40 is product step below 0W40. 0W40 carries MB229.5 approval and 5W40 does not (yet at least). MB229.5 is more stringent approval than VW 502.00 that you car calls for. xW or XXW are designations that determine cold performance. They do not indicate under any circumstances performance in warm weather. Actually, premier Castrol product is Edge 0W30, which is suitable for your car but it is $62 for 6qt on Amazon.
MEETS OR EXCEEDS INDUSTRY STANDARDS: API CF / SN ACEA A3/B4 BMW Longlife-01 MB-Approval 229.3 Porsche A40 VW 502 00 / 505 00
 
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Manchester, England
remember that 0w is thicker than SAE40 - 0w is NOT 'too thin'. What is the coldest ambient temp you will see during the OCI? That climate info will choose your W number for you wink
 
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