Dead or gas-free oil viscosity is determined as a function of crude oil . An Improved Temperature-Viscosity Correlation For Crude Oil Systems. It was found that it is not possible to generalize a correlation for the heavy oil viscosity using only API and temperature. However, the proposed. Find out the importance of measuring bunker fuel viscosity. Because of the viscosity & temperature relationship, a few extra degrees of pre-heating can often .
Oil viscosity -
Dead or gas-free oil viscosity is determined as a function of crude oil API gravity and temperature. The viscosity of the gas saturated oil is found as a function of dead oil viscosity and solution gas-oil ratio GOR.
Undersaturated oil viscosity is determined as a function of gas saturated oil viscosity and pressure above saturation pressure.
- Log in to your subscription
Table 2 Table 3 Comparison of different methods Fig. The results illustrate the trend for dead oil viscosity and temperature. As temperature decreases, viscosity increases. These tendencies make these methods unsuitable for use in the temperature range associated with pipelines. Dead oil viscosity correlations are somewhat inaccurate because they fail to take into account the chemical nature of the crude oil.
Only methods developed by Standing  and Fitzgerald    take into account the chemical nature of crude oil through use of the Watson characterization factor. Data should be acquired at temperatures over the range of interest. This method is recommended when measured dead oil viscosity data are available. Bubblepoint oil viscosity methods Table 4 Table 5 Correlations for bubblepoint oil viscosity typically take the form proposed by Chew and Connally.
That is why cold starts are so critical to an engine because the oil is cold, and so relatively thick. But, the lower the viscosity, the less the load the oil can support at the bearing on the crankshaft.
Oil Viscosity Explained
The higher the viscosity, the better the load it can support. Even this, however, has a trade-off, since the higher the viscosity, the more the drag at the bearing, and hence, potential power loss, or increased fuel consumption.
So a compromise is chosen to minimise power loss, but maximise load support. For domestic use, engine life is important, and in the main you should adhere to the recommended viscosity for your engine.
For motorsport, engine life is not critical, winning is, so these high performance engines can use lower viscosity oils to maximise power output to the wheels, but then again they generate a lot more heat so may use a higher viscosity anyway.
The larger the molecule structures, the thicker, or higher, or heavier the viscosity. The size and structure of mineral oil molecules vary, so the average molecule size dictates the viscosity, whereas the synthetic oil manufacturing process results in consistently sized molecules of an identical structure.
As mineral oil ages, the molecular size and structure changes and hence, the resulting changes in viscosity over the service life of the oil.