knightmb said:
I can watch the Gear Oil temperature slowly catch up and match it perfectly on the Probes.
That would agree with everything we think we know so far. I think we're on the right track in understanding all this. .... Gearbox gets cooled some by aluminum housing heat conduction (little bit of air cooling too), sort of indirectly from motor+inverter cooling radiator loops.
For the dynamics, I'm interested in something the Nissan gearbox engineers probably target & know about: The viscosity seems to settle out (equilibrium), within a certain reasonable range of ATF fluids, yet, as knightmb found, thicker ATF fluids create higher steady-state peak temperature affecting the entire metal "box" under the hood.
Note gearbox efficiency is better the lower the viscosity, and gearbox temperature is governed by power (heat) wasted in there, integrated with a gain as a function of the specific heat of the fluid plus metal.
That shows us it sort of settles into a stable viscosity state. At least as long as the coolant radiator loop is able to remove enough heat, which is certainly does. ..... ((( "Transfer Function" engineer geeks out there may consider this a basic 1st order Laplacian lag function with a variable time constant (tau) and disturbances, looking a bit similar to my old job modelling aircraft landing under wind gust disturbances. )))
I'd say, estomax
might want to think about removing the super-thick GL-5 gear oil in there after all, in light of knightmb's discovering slightly elevated temperatures with a mere 20% shift in ATF viscosities installed. Or at least monitor the LeafSpy temperature (motor-inverter one). Of course, if it gets really bad, the Leaf's own computer will light up a cockpit warning light, so there is that !! No warning light, no problem, .... although .... the cooler the underhood electronics & motor get, the longer that stuff lasts.
Like Nubo, I might consider trying the Valvoline ULV if I can get a cooler running aluminim chunk under the hood. Cooler fights ageing, less warrany claims for Nissan, and cooler means the ULV really functions at around the same ultimate visc as Matic S or Amsoil SS anyway!
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I need to take a drive in the mountains near Denver, since it's hot as Hades here, and car-makers love "hot & high" for durability testing of new models, months away from showrooms. I could see an Ioniq5 or something nice like that, who knows, as I've seen new model C8 Corvettes barreling up the mountain (Mt. Evans 14k ft) in the past, for example, before it hit showrooms.
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