Syntethic transmission fluid

[Norwegiandiesel]

Hi.
Consider to change the transmission fluid to synthetic. Do I have to, or should I, flush the transmission and cooler? Or is it good enough to drain, replace filter and fill it up with synthetic oil? Which should make a close to 50% mix of regular and synthetic fluids.
Thanks

 

[tanman_2006]

I can't tell on tap talk what tranny you have but on both my Allison and 4l80 I just drained and refilled then repeated at 25k.

source unknown

 

[Norwegiandiesel]

Hi.
Thanks.
The transmission is a 4L80E With a MagHytec deep pan.

 

[Mad Maxx]

You'll be fine with just draining as much as you can then refill with the new stuff. Just make sure it's all compatible and will Mix ok.

 

[wyrmrider]

More of a question
First- what is Synthetic? Castrol Definition of hydrocracked Dino oil group III base or Mobil 1 original Group IV (PAO)- Group V base and how do you tell? What is "Fully Synthetic" etc
Now your trans came with a DEX III type oil and may not be compatible with later (and much better) Dex VI
Dex VI is thinner, flows better when cold, has a better base stock, etc
If you want to use DEX III and can find a Group IV-V truly synthetic go for it- let me know when you wade through all the BS
Allison Certified TES 389 DEX III is about the best Dino Synthetic Dex III you can be sure of
an upgrade is MOPAR ATF +4 which IS synthetic (mostly highest quality type III and a premium additive package you can be sure of) I like it better than DEX VI
Best fluid is $$$ Allison Certified TES 295 to replace both DEX III and DEX VI
CITGO QUATRASYN is mostly TYPE IV-V Synthetic so it is not on the ALLISON approved list but has higher quality base stocks (developed years later) than TES 295 it should work like forever in a 4L80E
use it in your power steering/ power brake unit also

 

[EppNation]

More of a question
First- what is Synthetic? Castrol Definition of hydrocracked Dino oil group III base or Mobil 1 original Group IV (PAO)- Group V base and how do you tell? What is "Fully Synthetic" etc
Now your trans came with a DEX III type oil and may not be compatible with later (and much better) Dex VI
Dex VI is thinner, flows better when cold, has a better base stock, etc
If you want to use DEX III and can find a Group IV-V truly synthetic go for it- let me know when you wade through all the BS
Allison Certified TES 389 DEX III is about the best Dino Synthetic Dex III you can be sure of
an upgrade is MOPAR ATF +4 which IS synthetic (mostly highest quality type III and a premium additive package you can be sure of) I like it better than DEX VI
Best fluid is $$$ Allison Certified TES 295 to replace both DEX III and DEX VI
CITGO QUATRASYN is mostly TYPE IV-V Synthetic so it is not on the ALLISON approved list but has higher quality base stocks (developed years later) than TES 295 it should work like forever in a 4L80E
use it in your power steering/ power brake unit also

Amsoil Signature Series not make your list?

 

[wyrmrider]

Amsoil Signature Series not make your list?

Maybe but impossible to tell We know what ATF+4 is and Allison spec Transend but both are older specs with premium additive packages
The Citgo Quatrasyn has later synthetics, which have come down in price relatively since Transend and ATF+4 or DEX VI were developed
Redline and AMsoil should be fine
I'm using Quatrasyn and also in Power steering pump/ power brakes (not the brake fluid - DOT 4 there) it also works in NISSAN J, K N and most everything except Ford type F which should not be used in anything except where specked and some FORD Power steering- it has little or no friction modifiers
Someone with more patience than I have can go through the MSDS
several years ago the additive packages only came with type III so no product could be fully type IV-V
you saw quotes along that line
maybe there are later additive packages now, IDK
I'll leave it to the experts to determine IV PAO or V Ester -or what mix might be best for what application
MOPAR ATF +4 is a very cost effective "synthetic" blend- mix with excellent converter clutch- shudder expensive additive package way better than DEX III-Mercon