PART 4. FRESH OIL: A CLOSER LOOK
After just one test involving a car with oil change a power spike had been observed. It was decided that a closer look was necessary to determine the position and rate of power loss of this initial spike. As the entire spike was observed to be within the first 300 miles a shorter run was needed, and my calculations suggested that 1.25 mile run up + 9 laps + 650 metres = 60 miles. Also 1.25 mile run up + 12 laps + 1600 metres = 80 miles.
INITIAL TEST
TEST 1a. New Nissan R390 + Oil Change
A new Nissan R390 Race Car was purchased and the oil changed. The power (840BHP) was noted, then the car was handed to Bob who ran 60 miles at the test track. The power was again noted and Bob sent out for another 60 miles. This was repeated until 300 miles had been run. A graph of the results was plotted and deemed to show insufficient detail.
The console was reset returning the car to new condition (0 miles), and the experiment repeated with an initial run of 80 miles followed by 3 runs of 60 miles.
Again the console was reset and the experiment repeated with two runs of 80 miles followed by two runs of 60 miles. The data from these experiments was inserted into the original graph. The console was then reset once again to return the car to new condition for use in the long distance tests - I was not going to spend $4.5 million for just 300 miles!
Note:- Although this method allowed me to measure the power in 20 mile stages, it did not give results for the 20, 40 and 100 mile markers. However as no power loss had been observed before 120 miles these were assumed to also lie on the line of peak power.
TEST 1b. Used Nissan R390 + Oil Change
After running for over 9000 miles in long distance tests to reach the minimum power level, the same car was again given an oil change and the above test repeated to give a closer look at the power spike for a used car. Again multiple runs of 60 and 80 miles were required, and the data for 20, 40 and 100 mile markers assumed to lie on the same straight line as the 0, 60, 80 and 120 mile markers.
SUBSEQUENT TESTS
2. VW Nardo Concept + Oil Change
Due to the convoluted method of gathering data in the first test, the lack of any reliable 20 mile trackside marker, and a desire for greater accuracy I decided to alter the mileage between data points. Working towards an assumption of 6.2 miles = 10 km, thus 200 km = 124 miles, I settled on running 1.25 miles run up + 3 laps + 400 metres = 21 miles between data points.
A new VW Nardo Concept was obtained and the oil changed. The car was handed to Bob who ran 15 sessions of 21 miles at the test track. The power figure was recorded after each session and a graph plotted.
The car was then used for 12,000 miles of long distance tests before the oil was changed and this test repeated to look at the power spike in a used car.
3. Highly Tuned 2CV + Oil Change
To further narrow down the point of first power loss a combination of the above methods was used. An initial run of 60.5 miles (test 1 + additional 800 metres) was followed by a run of 21.5 miles (test 2 + additional 800 metres). There then followed 8 runs of 21 miles, and a final run of 60 miles.
The car chosen this time was a heavily tuned Citroen 2CV with these mods applied;
Racing Exhaust.
Stage 1 Turbo.
Racing Chip.
Port Polish.
Engine Balancing.
Fully Custom Transmission.
The transmission was adjusted by first moving the auto setting to maximum, then the final drive to maximum. The auto setting was then moved to minimum, and the final drive was also moved to minimum to create a car that could not pull away from a standstill under its own power, and could barely accelerate in 5th gear. The test was only made possible by the fact that there was a rolling start.
A 12,000 mile used car was run first for the allotted distance, power figures taken and a graph plotted. This previously used car was then used to win a new one and the experiment repeated to obtain the second set of results.
4. New Subaru Impreza Spec C
A new Subaru Impreza Spec C was bought and the stock oil retained. The car was given to Bob who ran for 315 miles at the test track in 21 mile stages. The power figure was recorded after each session and a graph plotted.
The console was reset to return the car to new condition (0 miles) and the oil was changed. The test was then repeated to obtain the power spike.
5. New Mazda BP Falken RX7
A new Mazda BP Falken RX7 was bought and the stock oil retained. The car was given to Bob who ran for 315 miles at the test track in 21 mile stages. The power figure was recorded after each session and a graph plotted.
The console was reset to return the car to new condition (0 miles) and the oil was changed. The test was then repeated to obtain the power spike.
6. New Amuse S2000 GT1
A new Amuse S2000 GT1 was bought and the stock oil retained. The car was given to Bob who ran for 315 miles at the test track in 21 mile stages. The power figure was recorded after each session and a graph plotted.
The console was reset to return the car to new condition (0 miles) and the oil was changed. The test was then repeated to obtain the power spike.
RESULTS
A table containing 32 data points was created for each of the six cars. These tables are not presented, but the graphs plotted from the data are shown.
ANALYSIS
Six cars were tested, and six spikes obtained for New cars after an oil change. Three of these cars were also tested in used condition after an oil change, the other three tested as new but without an oil change.
All of the new cars with fresh oil
(pink lines) exhibited the exact same behaviour. In all cases the oil change gave a 5% increase in power, and in all cases this was short lived disappearing at some point between 100 and 200 miles.
All of the used cars with fresh oil
(purple lines) exhibited a similar behaviour. The oil change would give a 10.525% increase in power - the reversal of the 5% power loss due to dirty oil combined with a 5% power boost due to servicing. Again the 5% boost due to servicing would be short lived, lasting for less than 200 miles.
All of the new cars
without oil change
(blue lines) behaved in a different way to those that had had their oil changed, but in the same manner as each other. There was absolutely no power loss at all from these cars during the first 300 miles.
Comparing new and used cars after an oil change shows that although there is a power difference due to permanant engine wear, the effect of the oil change is the same. A 5% boost from base power which is lost after the same additional mileage.
Comparing new cars with and without oil change, there is no difference in power once the 5% boost has worn off. This shows that the power boost due to GT Auto oil is
not due to a better blend of oil - unless this "race oil" miraculously reverts to standard oil after 200 miles. It must be due to the engine being in peak condition having just been serviced as suggested in part 1 of these tests.
ADDENDUM
By altering the Mileage axis between tests I had attempted to narrow down the exact points at which power loss began and ended. The first test clearly shows that the entire loss occurs between 120 and 200 miles, while the following two tests show that the start point is between 124 and 126 miles, and the end point between 187 and 189 miles. However, with the very low power levels of the Citroen 2CV in the third test there is the possibility of innacuracy.
I later discovered that Polyphony Digital appears to use 1 mile = 1600 metres, and 1km = 0.625 miles as conversion factors. This discovery lead me to believe that the actual start and end points were 125 miles (200km) and 187.5 miles (300km), something I was easilly able to confirm.
I took a new Lotus Elan S1, performed the oil change and gave it to Bob who ran two sessions of 60 miles. I then drove 0.5 mile sessions in A-spec mode, checking the power to weight ratio after each run. There was no change in the PWR at 125 miles, but there was the next time I checked at 125.5 miles.
Bob then ran another 60 mile session before I returned to running short sessions in A-spec mode. The PWR continued to change after every run, and at 187.5 miles was only 0.001 away from the stock value. I then ran a very short run before checking again. At 187.6 miles the PWR was the exact same as it had been before I changed the oil. I allowed Bob to run for a few more laps before one final check, and again the PWR was as it had been before the oil change.
CONCLUSIONS
* After an oil change, no power is lost for 125 miles (200km).
* Between 125 miles (200km) and 187.5 miles (300km) power is lost at a steady rate, returning to the base power level.
* After 187.5 miles (300km) there is again no power loss until the effects of engine wear begin at around 780 miles (1248km). I suspect that a test similar to this Addendum would show the point at which engine wear begins to be 750 miles (1200km).
