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Since the temps have reached the single digits here, i have noticed that my RPM's have increased until the engine is thoroughly warmed up.
At 70 mph my RPM's are 2000 when warm and 2400 when cold. At 60 mph (when cold) the the RPM's are at 2000. It takes a good 8-10 miles of 70 mph driving for the RPM's to drop.
1. Has anyone else noticed this behavior in cold weather?
2. Is this caused from the 5W30 motor oil being extremely cold or the trans fluid thickening up?
This behavior is entirely normal. The 5.4/4r100 combination delays locking the torque converter in cold weather until the engine warms up. This results in the engine running at higher rpms at highway speeds, which generates additional heat, and helps the truck warm up faster. Once the engine is adequately warmed, the truck will lock the torque converter and RPMs will be reduced appropriately.
Yep all 96-up OBD-II Fords do this. It's supposed to help the engine warm up faster, so that it goes into closed loop and leans out to keep the emissions down.
Jimmy