synthetic vs semi-synthetic thermal degradation
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wemay
Site Donor 2023
This was interesting...
Quote:
At an oxidation temperature of 120 °C, synthetic oil loses stability in the initial time period, while
it gains stability at longer ageing periods. Contrastingly, semi-synthetic oil exhibits stability
throughout the 240 h of ageing period at 120 °C. This can be correlated with the increase in
oxidation number, sulfation index and decrease in antiwear additive content in the case of synthetic
oil, while the variation of these quantities is insignificant in the case of semi-synthetic oil. This
demonstrates that even though synthetic oil ( Ea = 106.17 kJ mol−1
) is intrinsically more stable than
semi-synthetic oil ( Ea = 89.16 kJ mol−1
), the former loses stability at 120 °C owing to a relatively higher extent of oxidation. The constant value of Ea and the formation of long chain hydrocarbons
corroborates that semi-synthetic oil is oxidized to a relatively lesser extent than synthetic oil.
Quote:
At an oxidation temperature of 120 °C, synthetic oil loses stability in the initial time period, while
it gains stability at longer ageing periods. Contrastingly, semi-synthetic oil exhibits stability
throughout the 240 h of ageing period at 120 °C. This can be correlated with the increase in
oxidation number, sulfation index and decrease in antiwear additive content in the case of synthetic
oil, while the variation of these quantities is insignificant in the case of semi-synthetic oil. This
demonstrates that even though synthetic oil ( Ea = 106.17 kJ mol−1
) is intrinsically more stable than
semi-synthetic oil ( Ea = 89.16 kJ mol−1
), the former loses stability at 120 °C owing to a relatively higher extent of oxidation. The constant value of Ea and the formation of long chain hydrocarbons
corroborates that semi-synthetic oil is oxidized to a relatively lesser extent than synthetic oil.
wemay
Site Donor 2023
Very interesting indeed. But yes, rather technical.
MolaKule
Staff member
The math was good but the only criticism I have is with the sampling:
Quote:
Fully synthetic (Shell Advance Ultra, 10W-40) and semi-synthetic (Shell Advance AX7, 10W-40) engine oils were procured from Shell, and used as received. These two oils are used in four stroke
motorcycle engines, and are known to have good lubrication, shear stability and ageing resistance [22].
I would think 4 samples of differing Brands of 10W40's would have made for a better field of sampling. For example, include Delo, ExxoM, etc.
Then the question arises: What is it about the Shell formula makes these oil allegedly good? No comment.
Quote:
Fully synthetic (Shell Advance Ultra, 10W-40) and semi-synthetic (Shell Advance AX7, 10W-40) engine oils were procured from Shell, and used as received. These two oils are used in four stroke
motorcycle engines, and are known to have good lubrication, shear stability and ageing resistance [22].
I would think 4 samples of differing Brands of 10W40's would have made for a better field of sampling. For example, include Delo, ExxoM, etc.
Then the question arises: What is it about the Shell formula makes these oil allegedly good? No comment.
Last edited:
wemay
Site Donor 2023
Originally Posted By: MolaKule
The math was good but the only criticism I have is with the sampling:
Quote:
Fully synthetic (Shell Advance Ultra, 10W-40) and semi-synthetic (Shell Advance AX7, 10W-40) engine oils were procured from Shell, and used as received. These two oils are used in four stroke
motorcycle engines, and are known to have good lubrication, shear stability and ageing resistance [22].
I would think 4 samples of differing Brands of 10W40's would have made for a better field of sampling. For example, include Delo, ExxoM, etc.
Then the question arises: What is it about the Shell formula makes these oil allegedly good? No comment.
Yes, a larger, more diverse sample size would have been nice.
The math was good but the only criticism I have is with the sampling:
Quote:
Fully synthetic (Shell Advance Ultra, 10W-40) and semi-synthetic (Shell Advance AX7, 10W-40) engine oils were procured from Shell, and used as received. These two oils are used in four stroke
motorcycle engines, and are known to have good lubrication, shear stability and ageing resistance [22].
I would think 4 samples of differing Brands of 10W40's would have made for a better field of sampling. For example, include Delo, ExxoM, etc.
Then the question arises: What is it about the Shell formula makes these oil allegedly good? No comment.
Yes, a larger, more diverse sample size would have been nice.
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