I just did a road test. Used the voice recorder on my iPhone to record my water/oil temps as I said them while driving. As soon as I got home, I accidentally deleted the voice recording, sigh.
2007 Lotus Exige S
OEM dual oil cooler set-up
From my memory:
Outside temp 58 degrees; numbers at 3000-3500 rpm
first 6:00 40 mph +-
6:00-16:00 60-70 mph
16:00 on 40 mph +-
(A) Water temps increased more quickly than oil temps, water reaching 180F after about 4 minutes
(B) Oil temps did not reach 150 F until probably 8 minutes into driving, long after the water temps would have allowed me to engage the second cam
(C) Oil temps NEVER, EVER went above 150 F
Oil temps were measured in the pan.
Thoughts: I'm more keen to know my track temps with the OEM set-up, but if the oil is never getting above 150 F around town OR on the highway, I'd be wary of ever getting on to the second cam on the street. Good thing is, I dont, saving the lead foot for the track.
Also, seems like the OEM dual oil coolers, in my test have excess cooling capacity, meaning, the OEM oil thermostat is holding the oil temp right at 150 F. It never gets higher...meaning the oil coolers have too much cooling.
Seems like the Mishimoto with 200F thermostat is going to be necessary.