Economics of auto transmission maintenence

[MolaKule]

Originally Posted By: ledslinger
Never seen hard proof that frequent changes or boutique fluid ensures auto transmission life, but likely most here are confident it does. When you look at the expense and inconvenience of a transmission failure, and balance this with the relative pittance of overkill maintenance, penny pinching might be foolish.



...I suppose transmission expense paranoia drives my fluid regimen, even though I would rebuild myself if one failed. The job would be difficult to remove without a lift and a transmission jack...

Anyone else driven to overkill maintenance due to fear of auto transmission replacement or rebuild expense? What overkill steps do you take?



I think people want to thwart any premature fluid degradation which might promote a premature transmission failure. Now some transmissions have been known to possess internal failure points and modes which cannot be thwarted by regular ATF changes.

 

[meborder]

Originally Posted By: MolaKule
Quote:
The problem is that scenario #1 does not exist in nature, at least not outside of very extreme circumstances which will eventually result in an overheated engine.


And that is why many later vehicles have electric cooling fans to assist in cooling at idle, that is, once the temp gets high, extra air flow is forced through the radiator. My Nissan Frontier is but one example.


Only that the electric fan is there to cool the engine, not the transmission. Transmissions dont need cooling at idle.

To be honest I'm not seeing the connection to the topic at hand.

Quote:

Quote:
Think about it though, if the radiator could be used to heat the transmission fluid, why would they need an internal thermostat for the transmission?


Because not all vehicle AT's have the internal circulation path to rapidly allow the ATF to heat up. My Nissan Frontier is but one example.


Sure it does. I guarantee you that there is a fluid path in the event that the cooler lines become restricted. If it didn't, any vehicle like yours with a restricted cooling circuit would have a massive leak.

That is not to say that they had a need, desire, or the technology to have an internal thermostat for the transmission for that particular vehicle.

But the point is, if faster warm UPS are the goal, and they are, and the existing architecture would provide fast warm UPS by extracting heat from the radiator, why bother with a thermostat?

Quote:

I don't think we can apply all of the Ford results to all vehicles. The Ford results apparently apply to specific engines with specific transmissions with specific circulation paths.


I think it applies to far more vehicles than it doesn't. If your vehicle has an oil.to water transmission cooler on the cold side of the radiator, all of the above would apply. I can't think of any vehicle off the top of my head to which this wouldn't apply.

 

[MolaKule]

Originally Posted By: meborder
Originally Posted By: MolaKule


And that is why many later vehicles have electric cooling fans to assist in cooling at idle, that is, once the temp gets high, extra air flow is forced through the radiator. My Nissan Frontier is but one example.


Only that the electric fan is there to cool the engine, not the transmission. Transmissions don't need cooling at idle.

To be honest I'm not seeing the connection to the topic at hand.


To be honest, none of this really addresses the OP's comments and I agree.

I never said the electric fan was there to cool the transmission.


Originally Posted By: meborder
But the point is, if faster warm UPS are the goal, and they are, and the existing architecture would provide fast warm UPS by extracting heat from the radiator, why bother with a thermostat?



Not sure what your point is, but not all architectures before 2016 have that recirculating (closed loop) architecture for pre-heating.

 

[SirTanon]

Back to the main point of the OP's OP...

The bottom line here is that transmission design, and the fluid spec'd for said transmission, don't always work out the way the engineers intended.

For example, in my 2010 Fusion, the 6F35 transmission that is paired with my 2.5 liter duratec specs Mercon LV, and the manual lists a fluid life of 100,000 miles... and I think at one point this was back-spec'd to 60,000 miles..

.. but the truth of the matter is, this trans tends to be hard on the Mercon LV, does not have an oil pan, and the filter inside of it is not "user serviceable" by any stretch of the imagination. In fact, the only way to access the trans filter is basically to remove the trans and split the case...WAY too much work, if you ask me. In lieu of a pan, the 6F35 has a drain plug.

If you speak to any 'in-the-know' ford tech about this trans, they will tell you that the best approach, and the best way to extend the life of the filter, and really the trans as a whole, is to do a fluid exchange / drain-and-fill every 30,000 miles. For me, this would seem to be simple maintenance with the huge trade off of my trans lasting MUCH longer without having to worry about major maintenance and/or repair.

Given how easy it is to do a trans fluid drain/fill, and how cheap it is ($20 for a single drain and refill), I'd say it's a no-brainer.

 

[meborder]

Originally Posted By: MolaKule
Originally Posted By: meborder
Originally Posted By: MolaKule


And that is why many later vehicles have electric cooling fans to assist in cooling at idle, that is, once the temp gets high, extra air flow is forced through the radiator. My Nissan Frontier is but one example.


Only that the electric fan is there to cool the engine, not the transmission. Transmissions don't need cooling at idle.

To be honest I'm not seeing the connection to the topic at hand.


To be honest, none of this really addresses the OP's comments and I agree.

I never said the electric fan was there to cool the transmission.


Originally Posted By: meborder
But the point is, if faster warm UPS are the goal, and they are, and the existing architecture would provide fast warm UPS by extracting heat from the radiator, why bother with a thermostat?



Not sure what your point is, but not all architectures before 2016 have that recirculating (closed loop) architecture for pre-heating.


The point is that if the radiator imparted heat to the transmission, then every automatic transmission since the dawn of time had a closed loop system for pre-heating.

But it doesn't work that way.

The transmission fluid going to the radiator is always hotter than the coolant in the radiator. I highy doubt there is an exception, regardless of make or model, outside of one with a dramatically different architecture.

 

[zeng]

Originally Posted By: meborder
The laws of thermodynamics still apply, nobody is arguing that.
The problem is that scenario #1 does not exist in nature, at least not outside of very extreme circumstances which will eventually result in an overheated engine.
The following from mr. Kovalsky explains pretty clearly what happens under normal operation:

Quote:
The only time it is even close is at startup when the coolant and the ATF are at the same temperature. Once the engine starts the ATF starts to flow. It warms slowly, but the coolant around the radiator trans cooler doesn't warm at all, because the thermostat is closed. When the thermostat finally opens it dumps 200°F (more or less) coolant into the radiator. It doesn't stay open for long because the engine sucks ambient temp coolant in through the lower hose, causing the thermostat to close quickly. By the time this hot coolant gets the transmission radiator cooler it's back to near ambient. Remember, I had thermocouples in the radiator to measure this, I'm not guessing.

The quote in bold above is generally flawed and I find Molakule's points are valid.
A typical coolant thermostat's operating principles (from fully closed to fully opened or vice versa ) is analog in nature.

 

[Brad_C]

Originally Posted By: zeng

A typical coolant thermostat's operating principles (from fully closed to fully opened or vice versa ) is analog in nature.


It is, but there is a very good reason the temperature of the thermostat is specified at the temperature it *starts* to open. That is, there is *zero* flow (excepting the gnats whisker that dribbles through the bleed wobbler) into the radiator until the thermostat *starts* to open, and it does not do that until the specified temperature is actually reached. My transmission fluid leaving the converter is warmer than the ambient well before the thermostat even starts to open. Yes, I put a thermometer on the steel cooler line to actually measure it.

So, while yes it's analogue. There is a significant bias to ensure it does not start to open until it is actually supposed to.