Oil Viscosity
10-20-2015, 08:05 PM
#1
Oil Viscosity
Think you are outsmarting Porsche by using 5W-50 oil? Think again.
Oil Viscosity
Use the oil Porsche designed the engine to use (or a similar one). Don't follow the recommendations of the uninformed.
Oil Viscosity
Use the oil Porsche designed the engine to use (or a similar one). Don't follow the recommendations of the uninformed.
10-21-2015, 03:02 PM
#5
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The document that Todd92 linked is very informative. A careful inspection of the data on the figures is very informative. The data tell us that 0W-40 is best for excessively cold climates and 5W-50 is best for excessively hot climates. Moreover, the data say that 5W-50 is just fine for the winters in Florida.
I have a document from Porsche that states that Mobil 1 5W-50 is just fine for my 991 GTS. I also have a document that says 15W-50 is not good for the GTS but is intended for air cooled cars. I used it in my 993 for many years.
I have a document from Porsche that states that Mobil 1 5W-50 is just fine for my 991 GTS. I also have a document that says 15W-50 is not good for the GTS but is intended for air cooled cars. I used it in my 993 for many years.
10-21-2015, 04:31 PM
#6
The document that Todd92 linked is very informative. A careful inspection of the data on the figures is very informative. The data tell us that 0W-40 is best for excessively cold climates and 5W-50 is best for excessively hot climates. Moreover, the data say that 5W-50 is just fine for the winters in Florida.
I have a document from Porsche that states that Mobil 1 5W-50 is just fine for my 991 GTS. I also have a document that says 15W-50 is not good for the GTS but is intended for air cooled cars. I used it in my 993 for many years.
I have a document from Porsche that states that Mobil 1 5W-50 is just fine for my 991 GTS. I also have a document that says 15W-50 is not good for the GTS but is intended for air cooled cars. I used it in my 993 for many years.
10-21-2015, 05:59 PM
#7
It doesn't matter where you live. The design viscosity is 40 wt. The fact that 50 wt appears in the owners manual does not make it more desirable or in any way better for your engine. Porsche puts 0W-40 in at the factory for a reason. It's the optimum oil for the engine, in all climates. FL doesn't even count as excessively hot. Try Qatar or Dubai before reaching for the 5W-50.
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10-21-2015, 06:41 PM
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Todd92
If you look at Figure 7 of the useful publication you cite, viscosity does not differ significantly in oils until the temperature falls below 20 F. During the 40+ years I have lived in Florida, I have never been subjected to temperatures that low. As shown in Figures 8 and 9, viscosity is most dramatically affected by high temperatures. Granted the temperatures in Florida do not reach the elevated temperatures in these figures, but the data clearly show the oils that resist viscosity breakdown at elevated temperatures. As clearly stated in the article, the design for 40 weight oil is the thermostat. Thank you for your useful input.
If you look at Figure 7 of the useful publication you cite, viscosity does not differ significantly in oils until the temperature falls below 20 F. During the 40+ years I have lived in Florida, I have never been subjected to temperatures that low. As shown in Figures 8 and 9, viscosity is most dramatically affected by high temperatures. Granted the temperatures in Florida do not reach the elevated temperatures in these figures, but the data clearly show the oils that resist viscosity breakdown at elevated temperatures. As clearly stated in the article, the design for 40 weight oil is the thermostat. Thank you for your useful input.
10-21-2015, 06:59 PM
#9
Reread the section that discusses the impact of using higher than design viscosity. The higher viscosity oil has to shear more, which generates more heat, which in counterproductive. Not to mention the additional pumping losses.
Is there a reason for NOT using the design viscosity? There isn't one. The only one I've seen thrown around here are some UOA's that show thicker oil is...thicker. Accompanied by the nonsensical advice that "I like thicker oil, because it's...thicker".
If you really want to be a rebel and switch oils, reach for the Castrol 0W-40 5 qt jug, which can be found near the Mobil 1 0W-40 5 qt jug at Wal-Mart.
Is there a reason for NOT using the design viscosity? There isn't one. The only one I've seen thrown around here are some UOA's that show thicker oil is...thicker. Accompanied by the nonsensical advice that "I like thicker oil, because it's...thicker".
If you really want to be a rebel and switch oils, reach for the Castrol 0W-40 5 qt jug, which can be found near the Mobil 1 0W-40 5 qt jug at Wal-Mart.
10-21-2015, 07:17 PM
#10
I've yet to see any official documentation that specifically states that Porsche designed and optimized the 9A1 for 0W-40. All I see is that it's approved to use any A40 oil. And from what I can see, M1 5W-50 is listed right alongside M1 0W-40.
10-21-2015, 07:32 PM
#12
Because it's what they have on hand? Maybe it's easier to work with certain suppliers to get oil in bulk? Maybe it's the most cost-efficient oil that meets their specs?
Factory fill in no way implies any sort of design target or endorsement. That's what the approved oil specification is for and the 9A1 is specced for A40 oil. Any oil on that list has Porsche's seal of approval.
Factory fill in no way implies any sort of design target or endorsement. That's what the approved oil specification is for and the 9A1 is specced for A40 oil. Any oil on that list has Porsche's seal of approval.
10-21-2015, 07:53 PM
#13
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My Porsche dealer uses Penzoil 5w40 European formula.
Last edited by 9914s; 10-21-2015 at 08:40 PM.
10-21-2015, 08:21 PM
#14
Because it's what they have on hand? Maybe it's easier to work with certain suppliers to get oil in bulk? Maybe it's the most cost-efficient oil that meets their specs?
Factory fill in no way implies any sort of design target or endorsement. That's what the approved oil specification is for and the 9A1 is specced for A40 oil. Any oil on that list has Porsche's seal of approval.
Factory fill in no way implies any sort of design target or endorsement. That's what the approved oil specification is for and the 9A1 is specced for A40 oil. Any oil on that list has Porsche's seal of approval.
A40 is a Porsche specification. Oil that meets that spec just meets the spec. It does not get a Porsche seal of approval.
Are you implying that 0W-40 and 5W-50 perform identically because the both meet A40?
10-21-2015, 09:46 PM
#15
Every engine has a design viscosity. Porsche uses Mobil 1 because they have a marketing agreement with ExxonMobil. Porsche would have no problem getting all the 5W-50 from Mobil they wanted at the same price as 0W-40, if that is what their engineers wanted to use as the factory fill.
And no, M1 5W-50 would not come at the same cost as M1 0W-40. Around the time it went from SM to SN, M1 0W-40 transitioned to cheaper group III base stocks while 5W-50 remains a low-volume oil that's still comprised of group IV stocks.
That's because there's no such thing. It's a metaphor. But you can use any of the A40 oils and not void your warranty. That's a seal of approval as far as I'm concerned.