Dex III

[Zero]

This morning I'm having the transmission fluid and filter changed in my wife's daily driver; 2003 Pontiac Grand Prix, 3.8L 3800 II.

Anyhow, I realize that I should be/could be using Dex VI in this transmission for improved fluid life and performance, but I've got a case of AMSOIL Dex III that I need to use.

I usually drain the AMSOIL at 50,000mi regardless of the application and claims. How long would you recommend me using the Dex III before I drain and refill with DEX VI?

On another note, what make and model pump are some of you using to swap out transmission fluid without a filter change....is it a MityVac or what?

 

[SteveSRT8]

Be cautious as some older transmissions seem to have issues with D6.

 

[pbm]

I wouldn't hesitate to use Amsoil D-3 in that 4t65E. I'd actually prefer it over D-6.
I used Mobil 1 ATF in my Buick and it was running flawlessly when sold at 130K. If you've never changed the filter I'd drop the pan and change it (and clean the magnet)...otherwise I just inserted clear tubing in the dipstick tube and sucked it out.
After my initial change at 36K I went 60K on the Mobil 1.

 

[Zero]

Originally Posted By: pbm
I wouldn't hesitate to use Amsoil D-3 in that 4t65E. I'd actually prefer it over D-6.
I used Mobil 1 ATF in my Buick and it was running flawlessly when sold at 130K. If you've never changed the filter I'd drop the pan and change it (and clean the magnet)...otherwise I just inserted clear tubing in the dipstick tube and sucked it out.
After my initial change at 36K I went 60K on the Mobil 1.


Forgive my ignorance, but how did you determine my transmission is a 4t65E and how do I determine transmission types for my other vehicles?

 

[tnt31]

Originally Posted By: Zero

On another note, what make and model pump are some of you using to swap out transmission fluid without a filter change....is it a MityVac or what?



I use a Mityvac 7400. I like it but if I were buying a new Mitivac I think I would get the 7201.

 

[eljefino]

You can go by the RPO code in the trunk and by the pan shape which is generally at least somewhat unique.

A 4T60E and 4T65E might have the same pan though.

 

[MolaKule]

I wouldn't hesitate to use Amsoil D-3 in that 4t65E.

 

[Whitewolf]

Originally Posted By: SteveSRT8
Be cautious as some older transmissions seem to have issues with D6.


What issues?

 

[zzyzzx]

Originally Posted By: Whitewolf
Originally Posted By: SteveSRT8
Be cautious as some older transmissions seem to have issues with D6.


What issues?


I am also curious about this.

 

[brave sir robin]

Originally Posted By: SteveSRT8
Be cautious as some older transmissions seem to have issues with D6.


The guys on the Buick forum I belong to pretty much all say to use Dex VI. I myself am using supertech dex VI in my turbo 400 along with a bottle of lubeguard because why not? My car has 166k miles on what I'm pretty sure is the original transmission and it shifts smooth when driven nicely and firm when driven more aggressively. Before I changed out the old (It was a dark green color btw) fluid I noticed some high pitched noise when starting it on cold mornings. Changing the fluid and filter out has eliminated this issue entirely. I did this nearly a year and 10k miles ago and have had zero issues since. If I was able to do it all over again I would go with Max life instead of supertech.

 

[martinq]

Originally Posted By: zzyzzx
Originally Posted By: Whitewolf
Originally Posted By: SteveSRT8
Be cautious as some older transmissions seem to have issues with D6.

What issues?

I am also curious about this.

Same here. The FMs, base oil and additives used in D6 are all far superior the old DexIII spec.

I would use up the DexIII stash but I'm not sure I'd use any ATF for 50k without some decent/add-on filtering.

 

[martinq]

Originally Posted By: brave sir robin
I noticed some high pitched noise when starting it on cold mornings.

That is an indicator of cavitation from fluid that is too thick/cold/contaminated. A synthetic with good flow properties would prevent this and eliminate the damage that it causes.

 

[Gokhan]

Dexron-III was already a very good transmission fluid. I used Valvoline Dexron-III for about 15 years, changing it every other year or so, and about 3 years ago, I switched to the fully synthetic Valvoline Dexron-VI. I've never had any issues with my transmission but I can't tell if the transmission is doing better or worse with Dexron-VI, which is a little thinner than Dexron-III. Perhaps I will have a drain and refill next year and see if the wear is more or less than the typical. The transmission -- Aisin - Warner A240L (4-speed OD) -- is at 251,000 miles and is still working like clockwork.

 

[martinq]

Originally Posted By: Gokhan
I can't tell if the transmission is doing better or worse with Dexron-VI, which is a little thinner than Dexron-III.

A common misunderstanding. Dex6 flows better than Dex3 but provides better high-temperature and endurance protection.

So when used and at temperature, Dex6 will be heavier than Dex3 and have better clutch action at double the runtime.

 

[Gokhan]

Originally Posted By: martinq
Originally Posted By: Gokhan
I can't tell if the transmission is doing better or worse with Dexron-VI, which is a little thinner than Dexron-III.

A common misunderstanding. Dex6 flows better than Dex3 but provides better high-temperature and endurance protection.

So when used and at temperature, Dex6 will be heavier than Dex3 and have better clutch action at double the runtime.

Dexron-VI does have a smaller starting (new-oil) viscosity than Dexron-III. Therefore, initially, (at high temperatures) Dexron-VI will definitely be thinner than Dexron-III. However, Dexron-VI has less permanent oil shear because of stricter oil-shear specs. (It uses less viscosity-index improvers to achieve this and therefore higher-viscosity index base oil [synthetic blend or synthetic].) For this reason, while new Dexron-VI will be thinner than Dexron-III, used Dexron-VI may have about the same (high-temperature) thickness (viscosity) as Dexron-III. Note that Dexron-VI will definitely be thinner at very low temperatures, as it has synthetic base stocks in the mix.

 

[HTSS_TR]

I have Mityvac 7201 for about 10 years, I bought it to do oil change in the E430. I also use it to do ATF, Brake bleeding, PSF ... any liquid that is needed to be siphoned.

Just did an oil change for 2006 Volvo V70 yesterday, the Mityvac siphoned at least 95-98% of old oil from the sump. I checked the oil level before I change the oil, the level was at full line and capacity is 5.8 qt. Mityvac got about 5.4-5.5 qt and 0.3 qt drained from the cartridge filter holder. Removed the drain plug to check how much oil remained in the pan, no more than 20-30 drops of oil came out of the drain hold at the rate of 1 drop every 2-3 seconds.

Today I use Mityvac again to do brake bleeding after changing front pads for the E430. The brake pedal is a little firmer than before the pad and fluid changed.

Of all the tools I have, I have some but not a lot, the Mityvac 7201 is one of my favorite. It makes me smile every time I use it, especially when I do ATF or oil change or bleeding the brake, mainly because the job got done so easily and so clean all by myself. After the jobs were done, just pump the old fluid to a container for recycle.

Change oil for E430 the old fashion way:
Jack up the front, put jack stands at proper support point, remove splash guard, remove the drain plug to drain oil into a drain pan, change cartridge oil filter while the oil is draining, reinstall drain plug, reinstall splash guard, Jack up the car to remove jack stands, lower the car, clean up.

With Mityvac:
Hook up 2 hoses(15 seconds), insert larger hose into Mityvac(10 seconds), insert smaller hose into oil dipstick tube(10 seconds), pump the Mityvac 10-12 times(20 seconds), change cartridge oil filter while the pump is working, remove small hose from dipstick tube, remove larger hose from the pump, clean up.

Similar procedure for doing ATF.

PS If I put the value of $2 for every time I use Mityvac to change oil or ATF or Brake fluid because of convenience and time saving, I got back my initial purchase price of $6x 3-4 years ago, it's considered a free tool to me.

 

[MolaKule]

Originally Posted By: MolaKule
I wouldn't hesitate to use Amsoil D-3 in that 4t65E.


That should have said,
Quote:
I wouldn't hesitate to use Amsoil ATF or Redline D4 in that 4t65E.

 

[Jeff_in_VABch]

Originally Posted By: Gokhan
Originally Posted By: martinq
Originally Posted By: Gokhan
I can't tell if the transmission is doing better or worse with Dexron-VI, which is a little thinner than Dexron-III.

A common misunderstanding. Dex6 flows better than Dex3 but provides better high-temperature and endurance protection.

So when used and at temperature, Dex6 will be heavier than Dex3 and have better clutch action at double the runtime.

Dexron-VI does have a smaller starting (new-oil) viscosity than Dexron-III. Therefore, initially, (at high temperatures) Dexron-VI will definitely be thinner than Dexron-III. However, Dexron-VI has less permanent oil shear because of stricter oil-shear specs. (It uses less viscosity-index improvers to achieve this and therefore higher-viscosity index base oil [synthetic blend or synthetic].) For this reason, while new Dexron-VI will be thinner than Dexron-III, used Dexron-VI may have about the same (high-temperature) thickness (viscosity) as Dexron-III. Note that Dexron-VI will definitely be thinner at very low temperatures, as it has synthetic base stocks in the mix.


From the Redline website:
Our lowest viscosity, most shear-stable ATF for consistent operation

Synthetic D6 ATF is a lower viscosity version of the D4ATF and is designed for better fuel efficiency in CAFE testing. Dexron VI requires a different approach to a conventional ATF formulation. Rather than beginning with a 7.5 cSt fluid and allowing a viscosity loss in use to drop to 5.5 cSt, the Dexron VI fluid requires a starting viscosity of less than 6.4 and a final drop to no less than 5.5 cSt. Red Line D6 will drop to no less than 6.1 cSt. Since the final viscosity after use of these fluids are similar, Dexron VI fluids can be used where Dexron III fluids
were previously recommended (with the exception of some manual transmission applications, our customers report).

D6 ATF also provides significantly improved gear protection and will provide a GL-4 level of gear protection. The balanced frictional characteristics provide smooth and consistent shifts for extended drain intervals. The superior stability compared to petroleum ATFs allows high-temperature operation without varnishing valves and clutches which leads to transmission failure.

My take
So basically the Dexron VI starts as a 15% thinner ATF than III. For standard passenger car applications I dont see any downside to this fluid. The thinner fluid flows much faster in the valve body and allows much better friction plate lockup. There are only a few exceptions to using this such as the supercharged W-body cars. In these and similar, the differential transaxle is highly stressed and you would never use a thin ATF like Dexron VI as the differential would quickly fail under hard use.

 

[martinq]

Originally Posted By: Gokhan
Dexron-VI does have a smaller starting (new-oil) viscosity than Dexron-III. Therefore, initially, (at high temperatures) Dexron-VI will definitely be thinner than Dexron-III.

True, but the Dex3 has a fast shear-down so it won't take long for the viscosities to cross over. The operational viscosity of Dex6 is higher over most of the fluid life therefor it's more accurate to think of it as a 'thicker' fluid.

You can think of Dex3 as a 4.x or 5.x cSt fluid where Dex6 is a 6.x.

 

[Gokhan]

Originally Posted By: martinq
Originally Posted By: Gokhan
Dexron-VI does have a smaller starting (new-oil) viscosity than Dexron-III. Therefore, initially, (at high temperatures) Dexron-VI will definitely be thinner than Dexron-III.

True, but the Dex3 has a fast shear-down so it won't take long for the viscosities to cross over. The operational viscosity of Dex6 is higher over most of the fluid life therefor it's more accurate to think of it as a 'thicker' fluid.

You can think of Dex3 as a 4.x or 5.x cSt fluid where Dex6 is a 6.x.

No, the minimum allowable sheared viscosity for Dexron-III is 5.5 cSt, not 4.x cSt. It's the same (5.5 cSt) for Dexron-VI. In addition, minimum allowable doesn't mean that it will shear all the way down to 5.5 cSt. If it's made using quality viscosity-index improvers -- viscosity-index improvers simply being the very only reason why an oil shears -- it may hardly shear at all and the viscosity may stay close to 7.0 cSt. In most likelihood, a quality Dexron-III will be thicker than Dexron-VI in most conditions, even when it ages. This is the reason why GM doesn't recommend Dexron-VI for manual transmissions and power-steering systems that previously specified Dexron-III.

In my opinion though, you won't see any harm in manual transmissions and power-steering systems from Dexron-VI being a little thinner than Dexron-III. The viscosity difference is not that great and most protection in metal-to-metal contact (boundary-lubrication regime) comes from antiwear additives anyway.