krisk
Well-Known Member
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After much research, trial and error, I added an oil temperature gauge to my engine (GT PP). The main reason for doing this is because my car is a track only vehicle, and I am running 5w-50 oil at consistently high RPMs. I know the factory displayed oil temperature is an inferred value based who knows what all computer calculations and other actual measurements, so with the inferred number based on the factory recommended 5w-30, I wanted to know the actual temperature in case it is significantly different than what the car shows.
In the interest of offering some real world data for those who are using the factory recommended 5w-30, I sacrificed a case of full synthetic Motorcraft 5w-30 to do some on street (non track speed/rpm) testing. I have not found any published results of actual versus inferred oil temperatures for the S650, so I figured some others may be interested in the findings.
Here it goes for the 5w-30. At initial startup, the inferred and actual temps are within 2-3 degrees with the inferred always showing higher. As the oil warms up the inferred remains constantly higher than actual by 1-5 degrees until it gets to around 200 degrees. Once it hits 200 with no load (car in neutral) and the engine continues to rev at around 3500rpm, the actual temperature begins to exceed the inferred. With no load, I got the actual up to 222, but the inferred only showed 213.
I then did some road testing and found the inferred remained consistently higher until the oil temp was over 220. When the actual oil temperature was 230, the inferred showed 228. This was running 75mph at 4400 RPMs. Overall, the only time there was more than a 5 degree difference in actual vs inferred was when cruising at constant speed and low RPMs or transitioning between types of driving. When cruising at both 45mph and 70mph with the car in 10th gear, the inferred oil temperature would read 8-10 degrees higher than actual. Also, I found the inferred oil temperature changed slower with varied inputs than the actual. For example, when running at 75mph and 4400 RPM, which got the oil temperature up to 230, I then went to 10th gear and cruised for a couple miles. When I did this the actual oil temp dropped faster than the inferred. After the temperature stabilized the readings were again pretty close, but while dropping I saw up to a 10 degrees higher reading from the inferred numbers.
Overall, with 5w-30 the inferred number is pretty reliable with normal driving although it does seem to read high when just cruising at steady speeds. The photos I am posting are of running the engine with no load. You can see the actual temperature reading on the gauge in the left a/c vent.
I have not yet tested the 5w-50, but I’ll post those numbers as well once I swap out the oil and can get in some track time.
In the interest of offering some real world data for those who are using the factory recommended 5w-30, I sacrificed a case of full synthetic Motorcraft 5w-30 to do some on street (non track speed/rpm) testing. I have not found any published results of actual versus inferred oil temperatures for the S650, so I figured some others may be interested in the findings.
Here it goes for the 5w-30. At initial startup, the inferred and actual temps are within 2-3 degrees with the inferred always showing higher. As the oil warms up the inferred remains constantly higher than actual by 1-5 degrees until it gets to around 200 degrees. Once it hits 200 with no load (car in neutral) and the engine continues to rev at around 3500rpm, the actual temperature begins to exceed the inferred. With no load, I got the actual up to 222, but the inferred only showed 213.
I then did some road testing and found the inferred remained consistently higher until the oil temp was over 220. When the actual oil temperature was 230, the inferred showed 228. This was running 75mph at 4400 RPMs. Overall, the only time there was more than a 5 degree difference in actual vs inferred was when cruising at constant speed and low RPMs or transitioning between types of driving. When cruising at both 45mph and 70mph with the car in 10th gear, the inferred oil temperature would read 8-10 degrees higher than actual. Also, I found the inferred oil temperature changed slower with varied inputs than the actual. For example, when running at 75mph and 4400 RPM, which got the oil temperature up to 230, I then went to 10th gear and cruised for a couple miles. When I did this the actual oil temp dropped faster than the inferred. After the temperature stabilized the readings were again pretty close, but while dropping I saw up to a 10 degrees higher reading from the inferred numbers.
Overall, with 5w-30 the inferred number is pretty reliable with normal driving although it does seem to read high when just cruising at steady speeds. The photos I am posting are of running the engine with no load. You can see the actual temperature reading on the gauge in the left a/c vent.
I have not yet tested the 5w-50, but I’ll post those numbers as well once I swap out the oil and can get in some track time.
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