Originally Posted By: Bryanccfshr
Originally Posted By: BuickGN
Originally Posted By: Bryanccfshr
Originally Posted By: BuickGN
Originally Posted By: Bryanccfshr
Do you understand the practical differences between these very similar multiviscosity oils? Does the ILSAC rating that they all meet require more stringent wear protection for one grade over the other?...tell me what grades have more stringent requirements outside of viscosity which again is only a nominal difference.
Then why don't they spec a 20wt from the factory for slightly better fuel economy and all that other stuff the thin guys love to talk about?
What about the HTHS difference. I would venture a guess that since they spec'd a 10w-30 and not a 5w-30, there may be a higher HTHS requirement for that engine.
There is no more stringent HTHS requirement for a 10w30 over a 5w30 they both require a minimum 2.9 most the time the HTHS is the same between these grades. a 2.9-3.1 much higher and they cannot pass the fuel economy requirements. The minimum for a 5w20 is 2.6. Again this number varies by the particular blends ability to meet the fuel economy requirement. SOme are up to 2.9 some ar edown near 2.6 the rough mean difference is .3 between any. Are you going to say you trust production tolerance to garantee .3 differnce if your engine really needs .3 hths difference for its durability?
Normally, no. But this is in extreme heat and freeway driving is known to produce fairly high oil temps. I wouldn't be surprised if the oil was running 220 degrees or more.
Please refresh my memory. I can't scroll back up without erasing what I've already written. Can you elaborate on these fuel economy requirements and were these in effect when the car was produced? I'm really asking, I'm not trying to be smart.
As for the HTHS, going from your numbers alone, there could be a HTHS difference of .5. I consider that signifigant. It *could* be as low as 2.6 which we all know is the lowest acceptable HTHS to prevent excessive wear. Personally, I don't want an oil that's only capable of preventing "excessive" wear. I want something with a huge safety margin. With that said, I would feel even less comfortable if the car spec'd a 30wt which would mean the minimum the manufacturer designed it to never see less than a 2.9.
On the HTHS topic yes that is the max possible difference or as you see it the worst case scenario. I express mine in mean numbers to avoid having to average all the PDS's I could pull.(to much work for our pace of discussion)
OK Fuel economy pass fail criteria from SWRI
Pass/fail criteria for ILSAC GF-4 and API SM (minimum %FEI versus ASTM BC)
SAE 0W-20 and 5W-20 viscosity grades:
2.3% min. after 16 hours aging (Phase I FEI)
2.0% min. after 96 hours aging (Phase II FEI)
SAE 0W-30 and 5W-30 viscosity grades:
1.8% min. after 16 hours aging (Phase I FEI)
1.5% min. after 96 hours aging (Phase II FEI)
All other SAE viscosity grades:
1.1% min. after 16 hours aging (Phase I FEI)
0.8% min. after 96 hours aging (Phase II FEI)
More info here
http://www.swri.org/4ORG/d08/GasTests/VIBtest/default.htm
Reviwing that data I must concede that a 10w30 May get away with a very slightl/higher HTHS than a 5 or 0w30 due to it having a less stringent FE pass/fail factor.
Thank you. I have some reading to do. Got to spend less time with the 20vs 30 wars and more time keeping up to date with specs.