I have a 1995 Volkswagen Santana which is very similar to the US Volkswagen Quantum. This car uses the exactly same trans, a 3 speed automatic gearbox and recently i changed from Dexron II atf to Dexron VI atf. Using the Dexron II after running 10 miles or more was very common to get the radiator fan running about 6 or 8 minutes to cool down the gearbox after turning off the engine. It is a common feature among the automatic Santanas. Well, after changing the ATF to a Mobil Dexron VI atf this isn't happening. Doesn't matter if I run 10 or 30 miles the radiator fan stays running only about 1 minute after turning off the engine, nothing changed except the ATF. The only thing I can think of is that the new ATF is so much more efficient in thermal conduction that the radiator fan doesn't need to stay too much longer running, but I found nothing searching in Google to support this hypothesis. Can someone confirm to me if that does make sense? Thank you all.
Dexron VI thermal efficiency
- Thread starter ChristianBerg
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Full synthetic vs conventional base oil could very well explain this.
Originally Posted by CharlieBauer
Full synthetic vs conventional base oil could very well explain this.
Nothing related to the Dex VI specifications do you think?
Full synthetic vs conventional base oil could very well explain this.
Nothing related to the Dex VI specifications do you think?
Originally Posted by ChristianBerg
Originally Posted by CharlieBauer
Full synthetic vs conventional base oil could very well explain this.
Nothing related to the Dex VI specifications do you think?
Many specifications have a performance criteria which will define which base oils are able to be used.
Originally Posted by CharlieBauer
Full synthetic vs conventional base oil could very well explain this.
Nothing related to the Dex VI specifications do you think?
Many specifications have a performance criteria which will define which base oils are able to be used.
Originally Posted by ChristianBerg
Originally Posted by CharlieBauer
Full synthetic vs conventional base oil could very well explain this.
Nothing related to the Dex VI specifications do you think?
Well to be licensed as a DEXRON VI the base oil has to preform like a group III or better.
Originally Posted by CharlieBauer
Full synthetic vs conventional base oil could very well explain this.
Nothing related to the Dex VI specifications do you think?
Well to be licensed as a DEXRON VI the base oil has to preform like a group III or better.
Originally Posted by The Critic
Originally Posted by ChristianBerg
Originally Posted by CharlieBauer
Full synthetic vs conventional base oil could very well explain this.
Nothing related to the Dex VI specifications do you think?
Many specifications have a performance criteria which will define which base oils are able to be used.
I understand that. So would you agree the base oil could improve that much the thermal efficiency of the ATF making the transmission run cooler?
Originally Posted by ChristianBerg
Originally Posted by CharlieBauer
Full synthetic vs conventional base oil could very well explain this.
Nothing related to the Dex VI specifications do you think?
Many specifications have a performance criteria which will define which base oils are able to be used.
I understand that. So would you agree the base oil could improve that much the thermal efficiency of the ATF making the transmission run cooler?
Synthetics help with cooling but I have not witnessed more than a few degrees F in a passenger car.
Originally Posted by dave1251
Originally Posted by ChristianBerg
Originally Posted by CharlieBauer
Full synthetic vs conventional base oil could very well explain this.
Nothing related to the Dex VI specifications do you think?
Well to be licensed as a DEXRON VI the base oil has to preform like a group III or better.
That's interesting bacause Mobil call this ATF a semisynthetic oil.
Originally Posted by ChristianBerg
Originally Posted by CharlieBauer
Full synthetic vs conventional base oil could very well explain this.
Nothing related to the Dex VI specifications do you think?
Well to be licensed as a DEXRON VI the base oil has to preform like a group III or better.
That's interesting bacause Mobil call this ATF a semisynthetic oil.
Molakule posted about this. I recommend looking it up under technical papers.
Curious...where are the sensor(s) that signal the fan on/off?
Originally Posted by nascarnation
Curious...where are the sensor(s) that signal the fan on/off?
To be honest, I don't know. I've searched all over the internet to find that information. I don't know if the fan still running after the engine off just using the engine Coolant Temperature, or if there is a signal sensor only for the gearbox. I think there isn't a dedicated sensor.
Curious...where are the sensor(s) that signal the fan on/off?
To be honest, I don't know. I've searched all over the internet to find that information. I don't know if the fan still running after the engine off just using the engine Coolant Temperature, or if there is a signal sensor only for the gearbox. I think there isn't a dedicated sensor.
Originally Posted by dave1251
Molakule posted about this. I recommend looking it up under technical papers.
Found some Molakule posts on this and now I get it. Mobil doesn't consider Group III base oils to be Synthetic so they call it a semisynthetic. Anyways now I understand that the Mobil Dexron VI is way more efficient than the Dexron II I was using.
Molakule posted about this. I recommend looking it up under technical papers.
Found some Molakule posts on this and now I get it. Mobil doesn't consider Group III base oils to be Synthetic so they call it a semisynthetic. Anyways now I understand that the Mobil Dexron VI is way more efficient than the Dexron II I was using.
It's more about heat generation .
Heat generation delta as a result of traction coefficient between mineral Dexron II/III and (full/partial ?) synthetic Dexron VI is miniscule IMO.
You're likely encountering a scenario of substantial reduction of heat generation as a result of 'huge' difference in Coefficients of Friction related to additives from DII to D 6. .
Heat generation delta as a result of traction coefficient between mineral Dexron II/III and (full/partial ?) synthetic Dexron VI is miniscule IMO.
You're likely encountering a scenario of substantial reduction of heat generation as a result of 'huge' difference in Coefficients of Friction related to additives from DII to D 6. .
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I used mineral DEX3 from toyota for 2 years and i recently switched to penrite Full SYN Dex III and i found that the transmission runs cooler.
Never thought of the transmission causing the electric radiator fan to run longer / shorter , after engine shut down . Not saying it does not happened , just never heard of it & the thought never popped into my noggin .
My first exposure to DEXRON 6 was due to us purchasing a 2015 Chevy Sonic 1.8l automatic . I have heard about and used DEXRON , but did not pay much attention to the number designation . Though , so they are up to version 6 ?
All the DEXRON 6 I have come into contact has been synthetic or synthetic blend . None has been straight mineral oil .
How soon , after the fluid change out , did you first notice the change in the behavior of the radiator fan ? Immediately , days , weeks , months ?
Not saying your theory of better terminal efficiency is incorrect , but my thought is , MAYBE the DEXRON 6 is a better " cleaner " and has improved the thermal efficiency of the flow / heat transfer in the transmission and of the ATF cooler in the radiator ?
Please pass along any facts you discover . Interesting question .
Best of luck to you ,
My first exposure to DEXRON 6 was due to us purchasing a 2015 Chevy Sonic 1.8l automatic . I have heard about and used DEXRON , but did not pay much attention to the number designation . Though , so they are up to version 6 ?
All the DEXRON 6 I have come into contact has been synthetic or synthetic blend . None has been straight mineral oil .
How soon , after the fluid change out , did you first notice the change in the behavior of the radiator fan ? Immediately , days , weeks , months ?
Not saying your theory of better terminal efficiency is incorrect , but my thought is , MAYBE the DEXRON 6 is a better " cleaner " and has improved the thermal efficiency of the flow / heat transfer in the transmission and of the ATF cooler in the radiator ?
Please pass along any facts you discover . Interesting question .
Best of luck to you ,
Originally Posted by WyrTwister
Never thought of the transmission causing the electric radiator fan to run longer / shorter , after engine shut down . Not saying it does not happened , just never heard of it & the thought never popped into my noggin .
My first exposure to DEXRON 6 was due to us purchasing a 2015 Chevy Sonic 1.8l automatic . I have heard about and used DEXRON , but did not pay much attention to the number designation . Though , so they are up to version 6 ?
All the DEXRON 6 I have come into contact has been synthetic or synthetic blend . None has been straight mineral oil .
How soon , after the fluid change out , did you first notice the change in the behavior of the radiator fan ? Immediately , days , weeks , months ?
Not saying your theory of better terminal efficiency is incorrect , but my thought is , MAYBE the DEXRON 6 is a better " cleaner " and has improved the thermal efficiency of the flow / heat transfer in the transmission and of the ATF cooler in the radiator ?
Please pass along any facts you discover . Interesting question .
Best of luck to you ,
Well I noticed the difference immediately after the ATF change. As soon as I got in home after the ATF change. Today, the ambient temperature is a little bit higher than it was in the last few days. Later today I'll run about 15 miles with the car and let see if with a higher ambient temperature how much longer the radiador fan stays running after shutting down the engine. I'll come back soon with more information.
Never thought of the transmission causing the electric radiator fan to run longer / shorter , after engine shut down . Not saying it does not happened , just never heard of it & the thought never popped into my noggin .
My first exposure to DEXRON 6 was due to us purchasing a 2015 Chevy Sonic 1.8l automatic . I have heard about and used DEXRON , but did not pay much attention to the number designation . Though , so they are up to version 6 ?
All the DEXRON 6 I have come into contact has been synthetic or synthetic blend . None has been straight mineral oil .
How soon , after the fluid change out , did you first notice the change in the behavior of the radiator fan ? Immediately , days , weeks , months ?
Not saying your theory of better terminal efficiency is incorrect , but my thought is , MAYBE the DEXRON 6 is a better " cleaner " and has improved the thermal efficiency of the flow / heat transfer in the transmission and of the ATF cooler in the radiator ?
Please pass along any facts you discover . Interesting question .
Best of luck to you ,
Well I noticed the difference immediately after the ATF change. As soon as I got in home after the ATF change. Today, the ambient temperature is a little bit higher than it was in the last few days. Later today I'll run about 15 miles with the car and let see if with a higher ambient temperature how much longer the radiador fan stays running after shutting down the engine. I'll come back soon with more information.
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Ok guys, I've reached a conclusion. I've made today a 15 miles run with the car with heavy traffic and after shutting the engine off, the radiator fan kept running for about 10 minutes, what is the normal for this car. So I believe both the new ATF and the lower ambient temperatures we were experiencing here São Paulo the last few days contributed somehow to the lower radiador fan time I was getting. Maybe it was just a coincidence maybe not. In any case, I would like to thank you all for the helping me out with this question.
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