I saved the spec sheet (pdf format) from Castrol back in 2019, that was the spec until lately. I wish someone would (I've been busy) call Castrol and see if they'll report the new NOACK value for 5w30 Magnatec, the US version.
Pennzoil Platinum and Ultra Platinum NOACK values
- Thread starter Gokhan
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I saved the spec sheet (pdf format) from Castrol back in 2019, that was the spec until lately. I wish someone would (I've been busy) call Castrol and see if they'll report the new NOACK value for 5w30 Magnatec, the US version.
Here is a brief lesson on motor oil.
1. When the formulation of an oil changes (such as from SN PLUS to SP), the Noack will change. This is because the Noack primarily depends on two things: (1) base-oil viscosity and (2) base-oil quality. When the formulation changes, the blender will usually change the base-oil viscosity and readjust the KV and HTHS by adjusting the VII content. The base-oil quality usually remains about the same, as blenders are unlikely to resource their base stocks. Castrol typically uses low-end (cheaper) Group III base stocks in their oils marketed for the US (their ILSAC oils (as opposed to their ACEA oils)).
2. We have been seeing that the base-oil viscosity has been getting lower and the VII content getting higher with API SP oils because of the fuel-economy emphasis in SP.
3. Without doing any calculation, you can see that the SP is a lot thinner than the SN PLUS, as the densities are 0.8448 (SP) vs. 0.86 (SN). Likewise, the VIs are 175 (SP) vs. 159 (SN), showing the increased VII content and thinner base oil in SP.
4. You can use my VII/HTFS (base-oil viscosity) calculator to estimate the VII content and base-oil viscosity of Castrol Magnatec SN PLUS and SP. I get about 7% (SN) vs. 10% (SP) for the VII content and 2.0 cP (SN) vs. 1.8 cP (SP) for the base-oil viscosity.
5. This is my estimate of Noack for Castrol Magnatec 5W-30 SP. Assuming that similar base stocks are being used (similar base-oil quality), Noack × CCS should remain about constant. Therefore, we have 8.9% (SN) × 6010 (SN) = Noack (SP) × 4000 (SP). This gives Noack = 13.4% for Castrol Magnatec 5W-30 SP, which is on the high side for a dexos1 Gen 2 oil. If the base-oil quality has improved, it could be a little better, but I doubt it's much better than that, as I know Castrol's game in the US.
So, if Magnatec has made your engine consume less oil, it's good for you, but it's not because of the Noack. Perhaps you have a leak or valve-stem oil seal problems, and higher KV is helping you. Who knows. It's a mediocre synthetic, and there are better oils out there. I told you to get the top-of-the line Mobil 1 FS 0W-40 (or Castrol 0W-40), but you opted for a much lower-grade oil. You could have picked the Super Tech as well and saved yourself money, without seeing much difference in the performance.
As for motor-oil anecdotes, always take them with a grain of salt.
1. When the formulation of an oil changes (such as from SN PLUS to SP), the Noack will change. This is because the Noack primarily depends on two things: (1) base-oil viscosity and (2) base-oil quality. When the formulation changes, the blender will usually change the base-oil viscosity and readjust the KV and HTHS by adjusting the VII content. The base-oil quality usually remains about the same, as blenders are unlikely to resource their base stocks. Castrol typically uses low-end (cheaper) Group III base stocks in their oils marketed for the US (their ILSAC oils (as opposed to their ACEA oils)).
2. We have been seeing that the base-oil viscosity has been getting lower and the VII content getting higher with API SP oils because of the fuel-economy emphasis in SP.
3. Without doing any calculation, you can see that the SP is a lot thinner than the SN PLUS, as the densities are 0.8448 (SP) vs. 0.86 (SN). Likewise, the VIs are 175 (SP) vs. 159 (SN), showing the increased VII content and thinner base oil in SP.
4. You can use my VII/HTFS (base-oil viscosity) calculator to estimate the VII content and base-oil viscosity of Castrol Magnatec SN PLUS and SP. I get about 7% (SN) vs. 10% (SP) for the VII content and 2.0 cP (SN) vs. 1.8 cP (SP) for the base-oil viscosity.
5. This is my estimate of Noack for Castrol Magnatec 5W-30 SP. Assuming that similar base stocks are being used (similar base-oil quality), Noack × CCS should remain about constant. Therefore, we have 8.9% (SN) × 6010 (SN) = Noack (SP) × 4000 (SP). This gives Noack = 13.4% for Castrol Magnatec 5W-30 SP, which is on the high side for a dexos1 Gen 2 oil. If the base-oil quality has improved, it could be a little better, but I doubt it's much better than that, as I know Castrol's game in the US.
So, if Magnatec has made your engine consume less oil, it's good for you, but it's not because of the Noack. Perhaps you have a leak or valve-stem oil seal problems, and higher KV is helping you. Who knows. It's a mediocre synthetic, and there are better oils out there. I told you to get the top-of-the line Mobil 1 FS 0W-40 (or Castrol 0W-40), but you opted for a much lower-grade oil. You could have picked the Super Tech as well and saved yourself money, without seeing much difference in the performance.
As for motor-oil anecdotes, always take them with a grain of salt.
Castrol website had it several months or a year ago.
they still report it for Magnatec GTX Full Synthetic 10W30. It is 6.95
For CA, 10W is good. You have mild winters. I bought some 10W30 several months ago.
That Noack = 8.9% number for Castrol Magnatec 5W-30 was for the SN PLUS version, which had an unusually thick base oil (a synthetic base oil with a high CCS = 6010 cP), which was the reason behind the lower Noack. Castrol Magnatec 5W-30 SP should have a Noack ~ 13% according to my calculation in my previous post here, which is at the maximum limit for a dexos1 Gen 2 oil.
Yes, a 10W-30 version of an oil will typically have a much lower Noack than its 5W-30 version, as the base oil for the former is much thicker. If low Noack is desired and you don't live in a cold climate, go with the 10W-30 version.
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Yes, a good synthetic 10W-30 can be made with little VII. High-quality oils 0W-40 such as Mobil 1 FS 0W-40 and Castrol 0W-40 are made of top-of-the-line base stocks, and their VII content is not much higher than that of a mediocre synthetic 5W-30. See my my VII/HTFS (base-oil viscosity) calculator.10W30 has less plastic also. You know the "polymer" that is now in fashion (think 0W40).
I bought a jug of Castrol 0W40 Euro since it has many certs and approvals ... but haven't used it yet since no oil changes are due. The plastic thing is growing on me. lol
I compared the NOACK for a 5W vs 10W and was surprised by the large drop in NOACK for what seems like a small step up in thickness.
It's not a small step-up in "thickness." You need to look at the base-oil viscosity, not the blended-oil viscosity, the latter of which is modified by the viscosity-index improver (VII). Even though the KV100 and HTHS numbers for the 5W-30 and 10W-30 versions may be nearly identical, there is a large difference in the base-oil viscosity between the two, leading to a large difference in the Noack volatility. In layman's terms, to make a 10W-30, you start from a thick base oil with a low Noack volatility and add very little VII, whereas to make a 5W-30, you start from a thin base oil with a high Noack volatility and add a lot of VII so that you can raise the KV100 and HTHS to the SAE 30 viscosity range despite having started from a thin base oil.
You are new here, and you would think this would be known to people who have been on BITOG for long, but I bet 90% wouldn't be able to answer correctly why a 10W-30 version of an oil has a lower Noack volatility than its 5W-30 version!@Gokhan I suspected there was a good reason for that, and you would be able to explain it.
Even less known to almost everybody is that the 10W-30 version, despite having the same KV100 and HTHS, will be a lot thicker in the valvetrain and upper rings because that's where the viscosity-index improvers (VIIs) go under full temporary shear by fully aligning their molecules along the flow, effectively leaving only the base oil providing the viscosity in these parts of the engine. Likewise, a SAE 30 monograde will be even thicker in these parts. That's why I developed my HTFS (high-temperature, full-shear) viscosity (base-oil viscosity) calculator.
That's a great spreadsheet. I may download it and create a separate column for the grade (e.g., 5W-30) so I can filter on just those oils that match my needs.
Thank you Gokhan for creating the spread sheet for comparing oils.
I favor oils with as little VII as possible. When I lived in Socal, I used to use Shell Rotella straight 30 in my cars with great results. Now in New Hampshire in winter, I didn't like the straight 30 for cold starts (if the cars started at all). I learned the value of synthetic oils only after moving the the Northeast. Pennzoil Platinum 5w30 is my choice for the winter months. I may try PP 10w30 next winter.
I have been finding it difficult to find NOACK reports from anyone since PQI America stopped reporting the NOACK in the more recent tests.
Thanks for showing us how you determine probable NOACK results.
I am surprised by the differences in the 15w40 HDEO's and Mobil Delvac 1300 15w40 in particular. I have a 35 gallon stash of Delvac that I may used instead of my favorite Rotella 30..
I favor oils with as little VII as possible. When I lived in Socal, I used to use Shell Rotella straight 30 in my cars with great results. Now in New Hampshire in winter, I didn't like the straight 30 for cold starts (if the cars started at all). I learned the value of synthetic oils only after moving the the Northeast. Pennzoil Platinum 5w30 is my choice for the winter months. I may try PP 10w30 next winter.
I have been finding it difficult to find NOACK reports from anyone since PQI America stopped reporting the NOACK in the more recent tests.
Thanks for showing us how you determine probable NOACK results.
I am surprised by the differences in the 15w40 HDEO's and Mobil Delvac 1300 15w40 in particular. I have a 35 gallon stash of Delvac that I may used instead of my favorite Rotella 30..
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