The test was conducted on Dec 30, 2024. Temperature was set on the oven to what looked like ~ 420 F. A thermocouple reading on an oil with that same oven setting on Dec 27 said 431 F, when was ambient temperature was 47 F. Ambient temp. at start of this test was 60 F. Quaker State 5W-40 was included as the reference oil. All oils meet API SP, except for Delo that meets CK-4. I believe the causes of variation in trends are varying wind, varying ambient temperatures, and varying positions of the oils throughout the test. The oils were rotated right after each hour. If/when I do future volatility tests, I’m going to put a large box with an open top and bottom around the oven to block the wind, which should maintain a more consistent temperature. These variations are why in one of my other volatility threads, I said I would include error bars if it were straightforward to do in an honest and simplistic way. The measurement errors are small in comparison to error-inducing variations caused by unequal conditions above each oil. I will be switching over from doing volatility tests to only deposit and oxidation resistance tests.
Summary and discussion of the results: M1 5W-30 and VRP 5W-30 have extremely similar volatility. At hour 2, their cumulative losses were identical at 0.045 grams, which is 4.5% of their initial weights. Their volatilities are modestly respectable for a synthetic 5W-30. Nothing special there…mostly or entirely Group III of the non-GTL type and a typical viscosity index. Delo 5W-40’s volatility is disappointingly high. I bet it has a hefty dose of fairly shear-stable VIIs, requiring a relatively low viscosity base oil mix, raising its volatility. There could be another explanation like having a significant dumbbell blend of fairly low and fairly high base oils. As expected QS 5W-40 easily has the lowest volatility of these oils. Its Noack is believed to be 5.7%.
Summary and discussion of the results: M1 5W-30 and VRP 5W-30 have extremely similar volatility. At hour 2, their cumulative losses were identical at 0.045 grams, which is 4.5% of their initial weights. Their volatilities are modestly respectable for a synthetic 5W-30. Nothing special there…mostly or entirely Group III of the non-GTL type and a typical viscosity index. Delo 5W-40’s volatility is disappointingly high. I bet it has a hefty dose of fairly shear-stable VIIs, requiring a relatively low viscosity base oil mix, raising its volatility. There could be another explanation like having a significant dumbbell blend of fairly low and fairly high base oils. As expected QS 5W-40 easily has the lowest volatility of these oils. Its Noack is believed to be 5.7%.
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