Castrol 5W-40 (C 5W-40), Quaker State 5W-40 API SP (QS 5W-40), Quaker State Ultimate Durability 10W-30 (QS UD 10W-30), Amsoil SS 10W-30 (Ams SS 10W-30).
Please see the following two threads about past results.
https://bobistheoilguy.com/forums/t...rotection-volatility-results-nov-2024.389905/
The test procedure was like the previous except the oil temperature was ~420 F throughout entire test. Also different is that the oils were weighed in 1 hour intervals, then rotated right. Volatility results were collected up to 4 hours. QS 5W-40 is believed to have a Noack volatility of 5.7% and Amsoil SS 10W-30’s is published as 4.1%. I did make estimates of Noack volatility of the oils two ways, one by assuming QS 5W-40’s Noack and also by assuming Amsoil SS 10W-30’s Noack. Then I took the ratio of cumulative loss of oil A to the oil with known Noack, multiplied by the Noack of the oil whose Noack is known. Castrol 5W-40’s estimated Noack was around 10%. 10% is the maximum allowed by the MB 229.5 spec. that it meets. Noack estimate errors were at their minimum at hour 2. I want to not get in the habit of posting Noack estimates, because it involves correlating two different test procedures, which involves higher error than if I just provide the results from the test procedure used in my particular test. There is nothing magical or perfect about the Noack procedure. Oils are at an extremely wide range of temperatures in various engines at various times. They evaporate at different rates at different temperatures and even at different rates at the same temperature the longer they are in use.
I was disappointed in Castrol 5W-40’s volatility, but not surprised. It’s always seemed like an oil that Castrol purposely made as cheaply as they could get away with. For a while after MB 229.5 spec. existed, it still only met MB 229.3. At least they did an upgrade eventually to MB 229.5. The other thing I want to point out is that Amsoil lost significantly less weight after the first hour than it did compared to during the first hour. That’s why its cumulative weight loss is almost the same as QS 5W-40 at hour one, but then it diverges.
Please see the following two threads about past results.
https://bobistheoilguy.com/forums/t...rotection-volatility-results-nov-2024.389905/
The test procedure was like the previous except the oil temperature was ~420 F throughout entire test. Also different is that the oils were weighed in 1 hour intervals, then rotated right. Volatility results were collected up to 4 hours. QS 5W-40 is believed to have a Noack volatility of 5.7% and Amsoil SS 10W-30’s is published as 4.1%. I did make estimates of Noack volatility of the oils two ways, one by assuming QS 5W-40’s Noack and also by assuming Amsoil SS 10W-30’s Noack. Then I took the ratio of cumulative loss of oil A to the oil with known Noack, multiplied by the Noack of the oil whose Noack is known. Castrol 5W-40’s estimated Noack was around 10%. 10% is the maximum allowed by the MB 229.5 spec. that it meets. Noack estimate errors were at their minimum at hour 2. I want to not get in the habit of posting Noack estimates, because it involves correlating two different test procedures, which involves higher error than if I just provide the results from the test procedure used in my particular test. There is nothing magical or perfect about the Noack procedure. Oils are at an extremely wide range of temperatures in various engines at various times. They evaporate at different rates at different temperatures and even at different rates at the same temperature the longer they are in use.
I was disappointed in Castrol 5W-40’s volatility, but not surprised. It’s always seemed like an oil that Castrol purposely made as cheaply as they could get away with. For a while after MB 229.5 spec. existed, it still only met MB 229.3. At least they did an upgrade eventually to MB 229.5. The other thing I want to point out is that Amsoil lost significantly less weight after the first hour than it did compared to during the first hour. That’s why its cumulative weight loss is almost the same as QS 5W-40 at hour one, but then it diverges.
