Quote:
Originally Posted by Irace86.2.0
Yes the coolant heats faster than the oil. The difference is the Forester XT regulator circulates the warming coolant against the cool oil heating it up. Meanwhile, the coolant in the radiator is still cold because the coolant in the engine is warm but not hot, not hot enough to open the thermostat to circulate coolant through the radiator. Therefore, the oil in the JR setup is not being warmed—if anything it could be getting cooled by the radiator.
How much it matters or to what difference it makes, I don’t know.
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Yeah that's why depending on a lot of variables it could be slower or faster. So let's break this into two stages. Stage 1 the oil is running through the radiator, but the coolant isn't. Stage 2 both are running. Stage 2 begins when the thermostat opens. Variables being temp and air flow (Heat being drawn from the radiator), RPMs (Heat being applied to oil), and engine load (Heat being applied to coolant).
So worst case scenario is high air flow, low RPMs, and low engine load. This would maximize the time in stage 1 while maximizing cooling being done to the oil. Compared to no oil cooler, the oil is being heated slower.
The coolant will heat up faster than the oil, stage 2 will begin and the oil will begin to be heated. It will be at a faster rate than with no oil cooler as heat is now being transferred from the warm coolant to the cold oil. Compared to no oil cooler, the oil is now being heated faster.
Best case scenario is low air flow, high RPMs, and high engine load. This would minimize time in stage 1 while maximizing heating being done to counteract the heat drawn from the oil by the cooler. Compared to the other two scenarios, the oil is being heated at a rate somewhere in between.
Stage 2 will begin earlier and the oil may get up to temperature faster than stock. Compared to the other two scenarios, the oil is being heated faster in this stage.
I've attached a graph showing these hypothetical situations and how I'd expect the general shape of each scenario. I'm assuming the coolant thermostat opening at 5 minutes for best case scenario and at 10 minutes for the worst case. Keep in mind this is just a hypothesis and the values of the variables involved may be different than what I'm assuming so that even in the best case scenario it may be slower, or the worst case faster.
You can see how the variables in play will affect the time required to heat the oil and that until some thorough testing is done no one can definitively say one way or the other.