Best ATF fluid for built 4l80
TECH Addict
Joined: Jun 2009
Posts: 2,012
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From: Tulsa, OK
Using something that is full synthetic....your tranny will thank you. It's not unusual to see temps drop 20 degrees going from regular Dexron to a full synthetic oil. Don't get crazy worrying about viscosity, there not much you can do about it like you can with engine oil. Just get a quality full synthetic that meets Dexron spec. Also, put an aux cooler on it.
Here's an interesting chart showing trans life v. temperature.
http://www.tciauto.com/tc/trans-life-expectancy/
Here's an interesting chart showing trans life v. temperature.
http://www.tciauto.com/tc/trans-life-expectancy/
Using something that is full synthetic....your tranny will thank you. It's not unusual to see temps drop 20 degrees going from regular Dexron to a full synthetic oil. Don't get crazy worrying about viscosity, there not much you can do about it like you can with engine oil. Just get a quality full synthetic that meets Dexron spec. Also, put an aux cooler on it.
Here's an interesting chart showing trans life v. temperature.
http://www.tciauto.com/tc/trans-life-expectancy/
Here's an interesting chart showing trans life v. temperature.
http://www.tciauto.com/tc/trans-life-expectancy/
TECH Addict
Joined: Jun 2009
Posts: 2,012
Likes: 0
From: Tulsa, OK
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you realize the best fluid is whatever someone is running, lol
I have used nothing but cheap (nor really) NAPA Dex 3 or whatever they are calling it, it works fine-I have had the pan off several for various reasons, changing things, fluid always looks fine
some diff brands/types may tolerate temps better, but who knows, lol
I have used nothing but cheap (nor really) NAPA Dex 3 or whatever they are calling it, it works fine-I have had the pan off several for various reasons, changing things, fluid always looks fine
some diff brands/types may tolerate temps better, but who knows, lol
TECH Addict
Joined: Jun 2009
Posts: 2,012
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From: Tulsa, OK
That's like saying that a Duntov 30/30 cam is ok. It was fair in its day, unfortunately its day was over 40 years ago, and there are far better choices available today. You made the right choice with Dex 6. Your tranny will run probably 10-20 degrees cooler just because of the synthetic oil. Yes, it makes that much of a difference.
TECH Addict
Joined: Jun 2009
Posts: 2,012
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From: Tulsa, OK
If you don't want to change fluid often, put synthetic in, and then start using science instead of hearsay. Get it analyzed by a lab. Cost you $20 or so for each sample, and the results are 100% definitive about the condition of your oil. You'll save both time and money.
FormerVendor
Joined: Apr 2014
Posts: 263
Likes: 2
From: Justin, TX
I would use what your transmission builder recommends/requires (could prevent a warranty or lack of warranty situation).
In our transmissions, we use/recommend Dex-3.
Dex-6 was designed because of the modern applications that partially apply the torque converter clutch during cruising (mostly in the 6Lxx series of transmissions). This is recommended to be turned off for high performance converters, as it can burn up the friction material (that wasn't designed for it). Hence, Dex-6 is generally unnecessary, and just because something is advertised as "backwards compatible" doesn't necessarily mean it is the best for a particular situation.
In our transmissions, we use/recommend Dex-3.
Dex-6 was designed because of the modern applications that partially apply the torque converter clutch during cruising (mostly in the 6Lxx series of transmissions). This is recommended to be turned off for high performance converters, as it can burn up the friction material (that wasn't designed for it). Hence, Dex-6 is generally unnecessary, and just because something is advertised as "backwards compatible" doesn't necessarily mean it is the best for a particular situation.
Cheap brand (auto store brand, Wal-Mart, whatever) Dex III is good for most NA street/strip applications.
I would prefer to see more frequent fluid changes than an expensive fluid in a performance transmission.
My thoughts on synthetic fluid is that "generally" they are more resistant to heat. However even regular fluids have more heat capacity than the friction material used in auto transmissions. If you get the pan fluid temp to 300+*, the trans will need a rebuild anyway.
The exception to this is when you are heating the fluid in the converter due to a transbraked application, especially boosted where you may be sitting on the converter for extended time (5-7) seconds.
In the bigger HP applications, this can build a HUGE amount of heat and the fluid needs to be able to handle that as best as possible.
We've seen the John Deere Hygard and equivalents hold up well in these applications as well as some others that beat the fluid up.
One customer is making around 2000 HP in a turbo'd truck and may sit on the transbrake for 6-8 seconds to build boost. It has seen 700-800 degree fluid temps coming out of the converter.
I would prefer to see more frequent fluid changes than an expensive fluid in a performance transmission.
My thoughts on synthetic fluid is that "generally" they are more resistant to heat. However even regular fluids have more heat capacity than the friction material used in auto transmissions. If you get the pan fluid temp to 300+*, the trans will need a rebuild anyway.
The exception to this is when you are heating the fluid in the converter due to a transbraked application, especially boosted where you may be sitting on the converter for extended time (5-7) seconds.
In the bigger HP applications, this can build a HUGE amount of heat and the fluid needs to be able to handle that as best as possible.
We've seen the John Deere Hygard and equivalents hold up well in these applications as well as some others that beat the fluid up.
One customer is making around 2000 HP in a turbo'd truck and may sit on the transbrake for 6-8 seconds to build boost. It has seen 700-800 degree fluid temps coming out of the converter.
