Just for Ralphie!
Ok Ralphie, since I know you are a technical brother, I’ll bite. This is a valid question to ponder but IMO is not a problem with our dry sump system….But let’s prove it.
First, however, let me state my assumptions before launching into the calculations:
1. I do not know what the inside of our external oil tank looks like internally. The “full” oil hole on my dipstick is 10.75” from the top of the oil tank upper dome. The tank circumference is 25”, thus the residual volume in the tank (before fluid would be expelled out the dip stick opening from a “full” operating condition) assuming no internal structures above this full-level exist is calculated ((pi)((25”/(2*pi))^2)*10.75” = 534.96 cubic inches.
2. Coefficient of thermal expansion for our oil is 0.00039 1/F
3. Assume the starting oil temp is 70F and the final oil temp is 300F
4. Assume the oil system was previously filled to capacity i.e. the at-temperature oil level in the external oil tank was at the full mark before the extra one quart (32 fluid oz = 57.76 cubic inches) is added to the system.
Since the at-temperature standard oil fill is at the top of the dipstick level and all is fine, we need only worry about the extra quart of oil someone at the dealership may or may not have added to “overfill” the system. As Ralphie points out the oil will expand due to the (70F – 300F) temperature change (just like the air (or nitrogen) in our tires increases with temperature).
This fluid expansion is given by the formula dV = Vo*B*(T1-T0) where:
dV is the change in volume the oil experiences
Vo is the fluid volume which is to expand (in our case this is only 1 quart since the expansion of the initial 9.5 standard oil fill has already been accounted for by the Ford engineers in our as-designed external tank).
B is the coefficient of thermal expansion of the fluid (assumption 2)
T1 is the final fluid temperature and T0 the initial temperature.
Thus if we make the dV calculation using one additional quart or an additional 57.76 cu in of oil-
dV = (57.76 cu in)*(0.00039 1/F)*(300F – 70F) = 5.18 cu in of fluid volume change for the temperature increase
And the total at-temperature volume change in the external oil tank is the initial one quart overfill (57.76 cu in) plus the thermal expansion of this quart (5.18 cu in) = 62.94 cubic inches total.
Therefore since the external oil tank has extra volume capacity of about 535 cubic inches above the “full” dipstick mark (with the caveats stated in the assumptions) and the “expanded” extra quart occupies only about 63 cubic inches additional volume, it is no problem to have an extra quart.
Indy -
The only potential problem with an overfill that I can see would be the coefficient of thermal expansion which might lead to an overflow from the tank (leaking out the dipstick hole) as the engine heats up which might then lead to a fire as it reaches the exhaust manifold. Otherwise, no problem.
Ok Ralphie, since I know you are a technical brother, I’ll bite. This is a valid question to ponder but IMO is not a problem with our dry sump system….But let’s prove it.
First, however, let me state my assumptions before launching into the calculations:
1. I do not know what the inside of our external oil tank looks like internally. The “full” oil hole on my dipstick is 10.75” from the top of the oil tank upper dome. The tank circumference is 25”, thus the residual volume in the tank (before fluid would be expelled out the dip stick opening from a “full” operating condition) assuming no internal structures above this full-level exist is calculated ((pi)((25”/(2*pi))^2)*10.75” = 534.96 cubic inches.
2. Coefficient of thermal expansion for our oil is 0.00039 1/F
3. Assume the starting oil temp is 70F and the final oil temp is 300F
4. Assume the oil system was previously filled to capacity i.e. the at-temperature oil level in the external oil tank was at the full mark before the extra one quart (32 fluid oz = 57.76 cubic inches) is added to the system.
Since the at-temperature standard oil fill is at the top of the dipstick level and all is fine, we need only worry about the extra quart of oil someone at the dealership may or may not have added to “overfill” the system. As Ralphie points out the oil will expand due to the (70F – 300F) temperature change (just like the air (or nitrogen) in our tires increases with temperature).
This fluid expansion is given by the formula dV = Vo*B*(T1-T0) where:
dV is the change in volume the oil experiences
Vo is the fluid volume which is to expand (in our case this is only 1 quart since the expansion of the initial 9.5 standard oil fill has already been accounted for by the Ford engineers in our as-designed external tank).
B is the coefficient of thermal expansion of the fluid (assumption 2)
T1 is the final fluid temperature and T0 the initial temperature.
Thus if we make the dV calculation using one additional quart or an additional 57.76 cu in of oil-
dV = (57.76 cu in)*(0.00039 1/F)*(300F – 70F) = 5.18 cu in of fluid volume change for the temperature increase
And the total at-temperature volume change in the external oil tank is the initial one quart overfill (57.76 cu in) plus the thermal expansion of this quart (5.18 cu in) = 62.94 cubic inches total.
Therefore since the external oil tank has extra volume capacity of about 535 cubic inches above the “full” dipstick mark (with the caveats stated in the assumptions) and the “expanded” extra quart occupies only about 63 cubic inches additional volume, it is no problem to have an extra quart.