2005 5.3L Silverado-please advise on trans fluid

[TurboTravis]

Hey guys,

I bought my 2005 Crew Cab Silverado (5.3L gas) in 2010 with about 89K miles. I am pretty sure that the previous owner said that he changed all fluids at some point with AMSOIL. Fast foward to now, it has 197K and I have changed every fluid other than the trans fluid, which is still in 'good visual condition'. Nice red color, no burnt odor. My plan was to change out a couple quarts with each oil change. Here is my question-

GM started using Dexron 6 in 2006 as far as I can tell, and advising backwards compatibility with Dexron 3. I do not know if the previous owner used 6 or 3 when he serviced it. I am assuming the best choice here would be to use Dexron 6? I would like to take advantage of some of the Valvoline Dexron 3 on clearance at Wally World, but if not I'll survive.

Thanks
Travis

 

[SteveSRT8]

While Dex III is fine your truck was factory filled with dex VI. It is a far better fluid, a much better spec.

 

[barkingspider]

U can use Dex III, Dex VI, or Maxlife ATF without issue. I really like maxlife for the price so I would use that. U may want to do a filter change and replace all tranny fluid w new, that way you know what kind of tranny fluid u have in there

 

[Alex_V]

My go-to, that I've had good luck with so far, is Maxlife multi-vehicle ATF. A pan drop + filter will be fine.

 

[sweezy722]

I also have a 2005 purchased in 2010 and miles when purchased and now are very similar to yours.
I changed the filter and fluid on mine using maxlife atf. The pan can be a little difficult to get off due to shift arms and exhaust. My transmission shifted way to soft with the maxlife and pulling a boat. I completely flushed the transmission fluid at the return cooler line with Dexron VI. It has been great for 30,000 miles. Dexron III also works. I change fluid every 30,000 and filter every 60,000. I hear people say good things about maxlife and that is why I tried it but it will not go back in my vehicles. The Dexron VI at walmart is cheap and very good. I do use maxlife motor oil. I have also used pennzoil platinum but the motor would weep oil. It was just a drip here or there but I hated wipping up the occasional drip.

I have a 2004 suburban that had been abused by the previous owner.. I had the transmission rebuilt and put dexron VI in it as well.

The Dexron VI seems to shift better when cold and hot.

 

[46Harry]

I owned a 2005 Silverado that I purchased new. The recommended fluid for it was Dexron 3 H which is as far as I know is no longer available. If I still owned the truck I would use Dexron 6 in it.

 

[LeakySeals]

Dex III and Dex VI have different viscosity and chemistry. Dex VI is thinner. Not sure I would go that route in a Dex III tranny especially if its older. No matter what the compatibility claims are. Because transmission fluid serves a hydraulic function, so IMO going thinner may cause problems like slipping. FYI, Maxlife has changed over the years. Its latest batch is thinner than Dex VI. So IMO its quite a leap from Dex III to Maxlife.

I really like the O'rielly brand Dex III and Dev VI fluids. If you have one near you I would go that route.

 

[meep]

I ran Dex VI in a 1993 Jeep GC (the rare mix with the A/W trans), which originally came with Dex III. No issues and it shifted great. We put it in a friends ~2001 Chevy 1500 and it was also excellent.

IIRC, DEX III actually sheers down thinner than Dex VI during use, so the viscosity is not an issue.

-m

 

[CKN]

Originally Posted By: LeakySeals
Dex III and Dex VI have different viscosity and chemistry. Dex VI is thinner. Not sure I would go that route in a Dex III tranny especially if its older. No matter what the compatibility claims are. Because transmission fluid serves a hydraulic function, so IMO going thinner may cause problems like slipping. FYI, Maxlife has changed over the years. Its latest batch is thinner than Dex VI. So IMO its quite a leap from Dex III to Maxlife.

I really like the O'rielly brand Dex III and Dev VI fluids. If you have one near you I would go that route.


Doesn't GM say the Dex6 is backwards compatible?

 

[dogememe]

Dex VI is better than Dex III in every way - can't go wrong upgrading to that.

 

[kschachn]

Originally Posted By: CKN
Originally Posted By: LeakySeals
Dex III and Dex VI have different viscosity and chemistry. Dex VI is thinner. Not sure I would go that route in a Dex III tranny especially if its older. No matter what the compatibility claims are. Because transmission fluid serves a hydraulic function, so IMO going thinner may cause problems like slipping. FYI, Maxlife has changed over the years. Its latest batch is thinner than Dex VI. So IMO its quite a leap from Dex III to Maxlife.

Doesn't GM say the Dex6 is backwards compatible?

Yes. I thought it was explained that the difference is that over time the Dex VI has a more stable viscosity and the two essentially end up at the same value.

My old BMW runs fine on Walmart Dex IV, I tend to think that if it is OK then most any older car would be too.

 

[meborder]

If you think is filled with amsoil, consider sampling it to see if you need to do anything.

If it is full of signature series, you may be able to go a long long time before you need to do anything at all.

 

[zuluplus30]

Another vote for Dex VI. We’ve always done 50k fluid changes and 100k fluid/filter changes ever since Dex VI replaced III. Every trans has outlasted the engine and body including some long hard towing in a 4L60E

 

[4WD]

Mobil 1 Synthetic ATF is good in the pre Dex VI units … slightly thicker and high VI …
Know a shop owner who towed a huge cat hull (3 axle) and swears by it …

 

[SatinSilver]

Originally Posted By: kschachn
My old BMW runs fine on Walmart Dex IV, I tend to think that if it is OK then most any older car would be too.


What atf do you use in the Toyotas? That's what I'm interested in esp for the Matrix.

 

[JC1]

Originally Posted By: Alex_V
My go-to, that I've had good luck with so far, is Maxlife multi-vehicle ATF. A pan drop + filter will be fine.


+1 on this
I've used Mobil 1 ATF before switching to maxlife. Got the same performance on a 98 sienna with maxlife for half the price.

Are you towing lots with the truck?

 

[4WD]

Maxlife is thinner than Dex VI … fine for my Cruze … ~ I’d look thicker for HD towing in a pre Dex VI …

Seems Dex VI and Mercon LV hit the streets pretty close to the advent of 20’s in the motor …

 

[jj51702]

Whatever the owners manual states

 

[clinebarger]

2005 4L60E's were filled with Dexron III from the factory, The very next year GM switched to Dexron VI, 2005 & 2006 4L60E's are identical in EVERY way....You can run Dexron VI with confidence!!

That being said.....I run Castrol Transynd in ALL my GM transmissions.