Quote:
Originally Posted by Tristor
I guess this is somewhat off-topic, but I'm curious if you can expand on this. Right now, because I am using an engine oil cooler it takes longer for oil to come up to temperature on the street, especially in cold weather. Typically my process right now is to baby the car, but keep it rolling, until the blue cold engine indicator turns off, then to begin driving normally keeping the RPMs below 5k. Usually coolant temperature rises rapidly at this point until it hits the thermostat open point and then dips, until it levels out around the thermostat open point (192-195F I think). By the time the coolant has leveled out, my oil temp is usually still just around 160F, but I'll maintain keeping RPMs below 5k until oil temp hits its thermostat open point (190F), at which point I will begin using the full rev range.
My observation has been that oil temperature is directly correlated to RPM and time (or RPM over time, I guess). Despite that, I have always been concerned about abnormal/premature engine wear if I were to redline the car before the oil is fully up to temp. I tend to drive well into the redline because my feel of the car is that this engine prefers being pushed into the top end. I make it a point to bring the engine fully up to temperature and give it a few redlines on every trip before parking it (sometimes driving farther and making a loop if necessary, to ensure I am not short-tripping it at low temps).
Given that I'm tracking the car, I am trying to be judicious in how I treat it when it's not on the track to ensure as long of a life as possible before I have to replace the engine (which I assume will eventually happen no matter what). If 160F is warm enough to redline, am I doing more damage by waiting so long before giving it the revs since it holds the oil temp below its effective operating temperature longer? Would it be better to start giving increasing revs as soon as I cross 160F on the oil temperature to get it into operating range as quickly as possible?
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You just asked enough question to actually write quite a few technical papers on.
To make it short, you have to balance pressure vs flow. At too low a temp, there's too much resistance to flow, which is why the pressure is high. While the pressure is technically good, the flow is very bad, and the lack of flow can lead to a lack of lubrication at the end of the oil system.
The viscosity difference between 160F and 190F is fairly minimal, whereas the viscosity difference from 70F to 100F is very large. Viscosity is not linear with temperature.
Here's a chart for you, which I think will outline for you why 160F vs 200F is something considered fairly insignificant.
Another graph, "more zoomed in" showing the relative difference in scale vs the big picture graph above.
