tigeo
Autocross Champion
- Location
- Richmond, VA area
Oil temps. I read things all the time online that will state things like “XYZ oil dropped my oil temps 10 degrees” etc. I’ve never bought it. Here are my data. From my testing, it’s all based on ambient temp, RPM, and incline/decline of the road. I also believe elevation has an impact b/c it will impact engine cooling efficiency with our heat exchanger oil cooler – would need to test that but based on some info gleaned from a popular oil discussion forum (bobistheoilguy), this seems to be true. I have collected these data over a period of time (nearly a year) on the same commute (all highway) at the same speed (70mph), at the same time (driving time since start to collect reading), and going the same direction (to handle the slope as it’s downhill to work and uphill home…a 150’ elevation difference and I do note higher temps on my return trip at the same ambient). Elevations are in the 100-250’ msl range. I’ve controlled the variables to the extent that I can. I think folks just don’t understand how the oil temp varies and just flick their dash to oil temp and see what they see but don’t take into account the temp/speed/rpm portion of the equation. These are data from 3 different oils and there is no real difference under these conditions w/r to oil temp – all 3 trend lines are close.
Oils used:
LM Molygen 5W40
Mobil 1 5W40
Quaker State Ultimate Durability European Full Synthetic 5W40
I’ve also used LM Leichtlauf High Tech 5W40, added Ceratec and MoS2, and Mobil 1 0W40 but didn’t actually record any data for those. All of my memories are that these 2 would also fall on the same trend line based on the same conditions for this test. Of course you would need a v. long data collection period to get each oil across all the seasonal temp variations....but this is good enough for government work!
Bottom line – at 70 mpg/2500 rpm sustained for about 30 minutes, you get ~0.3 degrees change in oil temp for every 1 degree of ambient temp change regardless of xW40 oil brand. If you changed the speed/RPM you would just shift the line down or up but the slope should stay the same. I suspect if you changed to a xW30 you would also see an overall shift down.
Enjoy.
Oils used:
LM Molygen 5W40
Mobil 1 5W40
Quaker State Ultimate Durability European Full Synthetic 5W40
I’ve also used LM Leichtlauf High Tech 5W40, added Ceratec and MoS2, and Mobil 1 0W40 but didn’t actually record any data for those. All of my memories are that these 2 would also fall on the same trend line based on the same conditions for this test. Of course you would need a v. long data collection period to get each oil across all the seasonal temp variations....but this is good enough for government work!
Bottom line – at 70 mpg/2500 rpm sustained for about 30 minutes, you get ~0.3 degrees change in oil temp for every 1 degree of ambient temp change regardless of xW40 oil brand. If you changed the speed/RPM you would just shift the line down or up but the slope should stay the same. I suspect if you changed to a xW30 you would also see an overall shift down.
Enjoy.