Originally Posted by Gokhan
Originally Posted by ekpolk
Originally Posted by Gokhan
To give CATERHAM the credit he deserves, his motivation for his blend was his pursuit to optimize the HTHSV so that his oil pressure would be at the maximum at an RPM he desires, instead of at a lower or higher RPM. He had made the important discovery that the HTHSV governed the oil pressure, not the KV100 as one would naively think, which was a remarkable achievement.
The problem with the available oils is that they are either ILSAC, which have HTHSV less than 3.1 cP, or ACEA, which have HTHSV more than 3.5 cP. He wanted something right in the middle to optimize his oil pressure and he achieved that by mixing an ILSAC oil with an ACEA oil. It was an honest effort.
Thank you for that. I don't question CATERHAM's motives or his effort. What is a problem in my eyes, however, is his pattern of drawing conclusions and making claims that simply aren't supportable given the evidence and standards at hand. Shannow, notably, has plowed that ground deeply and thoroughly already. This situation is further aggravated by his doggedly emotional and occasionally downright hostile defense of the plainly indefensible. EDIT: I should have added that I'm not claiming that everything he posted is incorrect, he did offer some good solid information too.
Like the vast majority of members of this forum, I'm not an engineer of any sort (let alone a chemical/petro engineer), and my goal (beyond the fun of it) is of course to learn something. For that to work at all, you've got to remain teachable (and a bit of humility doesn't hurt either). CATERHAM didn't seem to get that at all.
CATERHAM is a scientist by education. He chose to do insurance for a living. If he hadn't studied science, he wouldn't be able carry out and analyze his ingenious experiments on oil pressure and oil blends.
I don't mix oil because I am a purist. However, mixing oil is OK if you want to have fun with it. You can experiment and do UOAs. There is nothing wrong with that.
Mixing a 0W-20 and 0W-40 will result in a 0W-xx virtually in all cases, as both have very thin synthetic base oils. 0W-40 usually has more VII, which increases the MRV and also the CCS to some degree but you're diluting it; so, in most cases, it will still be a 0W-xx, and even if it barely becomes a 5W-xx, it's no big deal.
Regarding the additives, yes, there can be problems, but I don't expect anything drastic, as we are talking about motor oil vs. motor oil, not motor oil vs. transmission fluid. As an extreme example, if one oil relies entirely on ZDDP and another entirely on friction modifier with no ZDDP to protect against wear, the resultant mix will have only half the ZDDP and half the friction modifier, which may not pass the engine wear test, but again, there won't be anything drastic that would damage your engine and you may not even see more wear in your UOA.
Besides, even the oil companies often fail regarding additive synergy and base-oil interchangeability -- high iron levels in some Mobil 1 oils in the past and high lead levels in Red Line probably have to do with the additive and base-oil synergy and the recent failure of Mobil Delvac to pass the Volvo oxidation test probably has to do with base-oil interchangeability. In each case, these oils would have failed a retest. Oil science is a very gray subject and it's probably more of an art than a science. There is nothing wrong if motor-oil enthusiasts on BITOG and elsewhere want to have fun with mixing different oils to create their own blend.
I agree with you. It's not going to be catastrophic if you mix oils. Most of the SN + oils are using Mg/Ca in very similar ratios so now more than ever it's fine to mix. Where I could potentially see it not being ideal is if for example you take an oil that has a Mg/Ca blend (SN +/D1G2) oil then add in some Redline or M1 0w40 which uses a lot of calcium and ZDP. You're then dealing with a detergent system that may not be balanced correctly with the level of FM's and AW additives. Oils are more alike than different, so in the general sense it's fine. I'm a purist as well and would rather keep the chemistry as similar as possible.
Originally Posted by ekpolk
Originally Posted by Gokhan
To give CATERHAM the credit he deserves, his motivation for his blend was his pursuit to optimize the HTHSV so that his oil pressure would be at the maximum at an RPM he desires, instead of at a lower or higher RPM. He had made the important discovery that the HTHSV governed the oil pressure, not the KV100 as one would naively think, which was a remarkable achievement.
The problem with the available oils is that they are either ILSAC, which have HTHSV less than 3.1 cP, or ACEA, which have HTHSV more than 3.5 cP. He wanted something right in the middle to optimize his oil pressure and he achieved that by mixing an ILSAC oil with an ACEA oil. It was an honest effort.
Thank you for that. I don't question CATERHAM's motives or his effort. What is a problem in my eyes, however, is his pattern of drawing conclusions and making claims that simply aren't supportable given the evidence and standards at hand. Shannow, notably, has plowed that ground deeply and thoroughly already. This situation is further aggravated by his doggedly emotional and occasionally downright hostile defense of the plainly indefensible. EDIT: I should have added that I'm not claiming that everything he posted is incorrect, he did offer some good solid information too.
Like the vast majority of members of this forum, I'm not an engineer of any sort (let alone a chemical/petro engineer), and my goal (beyond the fun of it) is of course to learn something. For that to work at all, you've got to remain teachable (and a bit of humility doesn't hurt either). CATERHAM didn't seem to get that at all.
CATERHAM is a scientist by education. He chose to do insurance for a living. If he hadn't studied science, he wouldn't be able carry out and analyze his ingenious experiments on oil pressure and oil blends.
I don't mix oil because I am a purist. However, mixing oil is OK if you want to have fun with it. You can experiment and do UOAs. There is nothing wrong with that.
Mixing a 0W-20 and 0W-40 will result in a 0W-xx virtually in all cases, as both have very thin synthetic base oils. 0W-40 usually has more VII, which increases the MRV and also the CCS to some degree but you're diluting it; so, in most cases, it will still be a 0W-xx, and even if it barely becomes a 5W-xx, it's no big deal.
Regarding the additives, yes, there can be problems, but I don't expect anything drastic, as we are talking about motor oil vs. motor oil, not motor oil vs. transmission fluid. As an extreme example, if one oil relies entirely on ZDDP and another entirely on friction modifier with no ZDDP to protect against wear, the resultant mix will have only half the ZDDP and half the friction modifier, which may not pass the engine wear test, but again, there won't be anything drastic that would damage your engine and you may not even see more wear in your UOA.
Besides, even the oil companies often fail regarding additive synergy and base-oil interchangeability -- high iron levels in some Mobil 1 oils in the past and high lead levels in Red Line probably have to do with the additive and base-oil synergy and the recent failure of Mobil Delvac to pass the Volvo oxidation test probably has to do with base-oil interchangeability. In each case, these oils would have failed a retest. Oil science is a very gray subject and it's probably more of an art than a science. There is nothing wrong if motor-oil enthusiasts on BITOG and elsewhere want to have fun with mixing different oils to create their own blend.
I agree with you. It's not going to be catastrophic if you mix oils. Most of the SN + oils are using Mg/Ca in very similar ratios so now more than ever it's fine to mix. Where I could potentially see it not being ideal is if for example you take an oil that has a Mg/Ca blend (SN +/D1G2) oil then add in some Redline or M1 0w40 which uses a lot of calcium and ZDP. You're then dealing with a detergent system that may not be balanced correctly with the level of FM's and AW additives. Oils are more alike than different, so in the general sense it's fine. I'm a purist as well and would rather keep the chemistry as similar as possible.
