Warming up the transmission for that first shift of the day

[BRRV]

Why would there be inadequate lubrication? Because it's cold?

I have no idea. I think my brain was thinking one thing and saying another. Let me try to explain and you guys can tear it apart. As I recall, oil circulates and protects best when at operating temperature - clearly, at 5 degrees, it would take longer for it to provide the best shear protection (I'm no API engineer - just repeating what I've read) and an engine under load, or at high(er) revs, would stress the oil more, perhaps exceeding the capabilities of a given oil in those first few critical minutes when running, even to the point where the barrier of oil protection could be compromised. Do I have any direct evidence to support this? No. I do know that most automotive junkies and pundits (myself included) take for granted the idea that one shouldn't stress a cold engine because of the potential for increased wear. The (family) Honda CRV ("the appliance") even says that somewhere in the owners manual.

I just think that getting some temperature in the oil, letting engine parts receive the benefit of a little heat without load, is beneficial, versus the alternative, starting and driving it away at 5 degrees and immediately trying to keep up with the other traffic that IS already warm. By the way, at that temperature, my M30 is a little clattery for the first minute or so, a combination of piston slap and slight rocker noise. On an original bottom end with 270,000 miles, I'm all for giving it a chance to warm a bit.

[tn535i]

I think your on track with your thoughts. Consider this also. The gear pump is positive displacement but the oil is very thick at cold temps. I'm talking well below freezing. If you rev it up much it will generate huge amounts of pressure as it tries to pump that thick oil through the filter and into the bearing rifles. In that case most of it will just dump through the high pressure relief valve back into the sump or the pump may even cavitate. Not all models have a filter bypass but if the oil is very cold it will go this way rather than through the filter. So now you might not just be shy on lubrication flow, you are also stressing your oil pump much more than normal.

The hydraulic pressure in the pump is one big reason for really hard cranking in very cold weather. If I notice the engine seems to crank hard at all I will definetely let mine idle a bit and warm up before giving any revs to the motor.

[Scottinva]

Why would there be inadequate lubrication? Because it's cold?

I have no idea. I think my brain was thinking one thing and saying another. Let me try to explain and you guys can tear it apart. As I recall, oil circulates and protects best when at operating temperature - clearly, at 5 degrees, it would take longer for it to provide the best shear protection (I'm no API engineer - just repeating what I've read) and an engine under load, or at high(er) revs, would stress the oil more, perhaps exceeding the capabilities of a given oil in those first few critical minutes when running, even to the point where the barrier of oil protection could be compromised. Do I have any direct evidence to support this? No. I do know that most automotive junkies and pundits (myself included) take for granted the idea that one shouldn't stress a cold engine because of the potential for increased wear. The (family) Honda CRV ("the appliance") even says that somewhere in the owners manual.

I just think that getting some temperature in the oil, letting engine parts receive the benefit of a little heat without load, is beneficial, versus the alternative, starting and driving it away at 5 degrees and immediately trying to keep up with the other traffic that IS already warm. By the way, at that temperature, my M30 is a little clattery for the first minute or so, a combination of piston slap and slight rocker noise. On an original bottom end with 270,000 miles, I'm all for giving it a chance to warm a bit.

This happens even when the engine is cold, even if outside temp is warm. It just so happens when the outside temp is very low such as what you guys are experience, this problem is amplified.