ATF Fluid with most heat cycle resistance?

[FlyPenFly]

This is for a NC Miata auto-trans (actually it's for a Fiat 124 Abarth but it uses the NC transmission in a different housing).

Redline is not listed here but I believe the D4 ATF is compatible according to their site. Which fluid would you pick if the car will be autocross and tracked every month. An ATF cooler might eventually be installed if temperature becomes a real problem. Fluid will be changed annually and car has 45k miles on it today.

This what RockAuto lists as compatible.

 

[GSCJR]

I'm wondering if a TES-295 fluid would more suited for your application. Maybe @clinebarger can advise here?

 

[MolaKule]

Please explain by what you understand to be "Heat cycle resistance."

Every ATF has thermal conduction and convection coefficients.

Yes, if the temps get too high add an ATF oil cooler in the circuit.

 

[nascarnation]

I'd recommend measuring temps using a heat gun just for interest sake.
Your Allison TES-295 / 668 fluids are going to be robust because of the PAO base.
However you can have issues with heat effect on polymers in the transmission even if the fluid is not breaking down.
Temp data should lead you in the right direction on possible need for cooler upgrades.
But if most of your running is in TCC lock, your automatic may not be making all that much heat.

 

[FlyPenFly]

Please explain by what you understand to be "Heat cycle resistance."

Every ATF has thermal conduction and convection coefficients.

Yes, if the temps get too high add an ATF oil cooler in the circuit.

Track temps frequently overheat ATF which requires giving the car a longer break between sessions. When the heat gets high enough it causes some breakdown of the fluid.

 

[97prizm]

This is for a NC Miata auto-trans (actually it's for a Fiat 124 Abarth but it uses the NC transmission in a different housing).

Redline is not listed here but I believe the D4 ATF is compatible according to their site. Which fluid would you pick if the car will be autocross and tracked every month. An ATF cooler might eventually be installed if temperature becomes a real problem. Fluid will be changed annually and car has 45k miles on it today.

This what RockAuto lists as compatible.

View attachment 291272

Is it a six-speed automatic? Torque converter or dct?

 

[Carlostrece]

A good ATF cooler is a low cost, effective upgrade.

 

[Revving2Redline]

A good ATF cooler is a low cost, effective upgrade.

So is changing it often too. Maybe a higher capacity pan or ones with cooling fins and or also.

 

[Carlostrece]

So is changing it often too. Maybe a higher capacity pan or ones with cooling fins and or also.

An aluminum pan would transfer heat faster than a steel pan. Even moreso if it has fins on the outside.

He could change ATF more often, but over longterm that wastes oil and time.

Efficient solutions are installing an ATF cooler and also installing an aluminum pan, or steel pan with fins, or ideally an aluminum pan with fins.

If better qualty ATF exists, that would also be an upgrade. However, I think there's still no subsitute for adequate cooling, especially in a hot climate or when racing.

 

[Revving2Redline]

My BC5a CVT doesn't allow for a cooler, the external outlets are for the coolant to warm up the fluid faster, so I went the other route of Redline Nonslip CVT Fluid and ultra frequent interval changes. Two more changes of it and then I am migrating over to @High Performance Lubricants CVT so I know that Dave will be thrilled! After I get the rear main seal fixed/transmission replaced I will use up the remaining 8 qts of Redline 0w30, but til then its top end hm syn oil from Walmart and Schaeffer's #132.

 

[Carlostrece]

A trans cooler is inexpensive. An aluminum pan with fins is affordable enough. These are not expensive upgrades, but they are effective upgrades.

 

[Carlostrece]

Another good low cost ATF upgrade would be a Magnefine in-cooling-line ATF filter. @Sequoiasoon told me about this upgrade recently. I plan to install Magnefine on a Honda CR-V and Buick Park Ave. It'd probably be good for Mazda too.

I suggest: Find out if your Miata already has an OEM or aftermarket in-cooling-line ATF filter installed. If it does, then replace it with a Magnefine. If your Miata doesn't currently have an in-cooling-line ATF filter, then add a Magnefine inline filter.

This is an upgrade to your ATF no matter what type ATF you use. IMO

Magnefine in-cooling-line ATF filter is explained and discussed in posts 96, 102, 104, 106 in this thread https://bobistheoilguy.com/forums/threads/maxlife-atf-compatibility.396644/post-7331785

 

[thescreensavers]

+1 on Magnefine filters I've added them to all my automatic transmission vehicles!

 

[johnmyster]

An aluminum pan would transfer heat faster than a steel pan. Even moreso if it has fins on the outside.

He could change ATF more often, but over longterm that wastes oil and time.

Efficient solutions are installing an ATF cooler and also installing an aluminum pan, or steel pan with fins, or ideally an aluminum pan with fins.

If better qualty ATF exists, that would also be an upgrade. However, I think there's still no subsitute for adequate cooling, especially in a hot climate or when racing.

Oil pan marketing overlooks the substantially higher thickness of aluminum pans, which tends to offset the higher conductivity (roughly 4x) and fins. That relatively thin stamped steel pan is a better conductor than typically assumed.

For oil cooler loops that have a heat exchanger in the radiator, once the radiator is heat soaked the engine may still be adequately cooled, but the radiator is effectively heating the trans fluid. Under normal driving the trans cooler is sitting in water close to ambient air temperature. Under hard conditions and low airflow, that water is closer to engine temperature. Robust trans fluid to air cooling becomes the answer.

 

[Pablo]

The first synthetic ATF. Very heat resistant.

https://www.amsoil.com/p/amsoil-sig...ic-automatic-transmission-fluid-atf?zo=515729

 

[Carlostrece]

Oil pan marketing overlooks the substantially higher thickness of aluminum pans, which tends to offset the higher conductivity (roughly 4x) and fins. That relatively thin stamped steel pan is a better conductor than typically assumed.

I don't know the actual numbers to compare conductivity, but I see your point. What you said sounds plausible.

When I needed more ATF cooling for my Jeep, I relied on an air-cooled ATF oil cooler mounted 2 inches in front of the radiator (not touching the radiator). I had a skidplate under the engine & trans pans. So a finned pan was not an option. The air cooled ATF oil cooler worked well.

For oil cooler loops that have a heat exchanger in the radiator, once the radiator is heat soaked the engine may still be adequately cooled, but the radiator is effectively heating the trans fluid. Under normal driving the trans cooler is sitting in water close to ambient air temperature. Under hard conditions and low airflow, that water is closer to engine temperature. Robust trans fluid to air cooling becomes the answer.

 

[nascarnation]

Oil pan marketing overlooks the substantially higher thickness of aluminum pans, which tends to offset the higher conductivity (roughly 4x) and fins. That relatively thin stamped steel pan is a better conductor than typically assumed.

That would definitely make for an interesting back to back test. Especially on vehicles like the OP where there's not much airflow under the car in the first place.
Hot Rod seems to think the pan works but I'm not too impressed with their test technique.
https://www.hotrod.com/how-to/hrdp-1305-does-a-finned-aluminum-trans-pan-really-do-anything

 

[MolaKule]

The point is, there is no such ATF oil property as heat cycle resistance.

The Amsoil ATF listed above in Post 15 or the HPL ATF BlueCC should work.

You want an ATF with a high level of PAO for extreme heat variations.

 

[BrendanC]

Add an external cooler and filter. helps keep the ATF cooler and cleaner. added external coolers and fram ph8a sized filters on both accords and my pickup (just a larger external cooler on it because it came with one factory)

 

[johnmyster]

That would definitely make for an interesting back to back test. Especially on vehicles like the OP where there's not much airflow under the car in the first place.
Hot Rod seems to think the pan works but I'm not too impressed with their test technique.
https://www.hotrod.com/how-to/hrdp-1305-does-a-finned-aluminum-trans-pan-really-do-anything

But that wouldn't be good aftermarket custom parts marketing. Aluminum is a better conductor so buy the better thing, right?

Same with all the differential covers. The fins and the material conductivity have to be beneficial enough to overcome the fact that the cast cover is thicker than the stamped steel.

I'm going to make one from thin copper and have the best of both worlds.