Dexron VI ATF Fuid - Preference/Best

K

Killjoy

Forum Member
Hey guys - qq:

Getting ready to do a trans filter change and fluid swap in my truck a couple weeks. Any preferences on a particular Dexron VI fluid to use? I've been reading up online and driving myself bonkers - no simple answer on what's "best". I was hoping to use a "full synthetic" fluid... was disappointed to find that the Mobil and Castrol Dex6 are both a synthetic blend. I always hear about Redline and Amsoil being the "best", but I'm somewhat concerned that neither has an officially certified Dexron VI fluid - both just claim to be compatible, etc.. Valvoline has a "full synthetic" that's about $8/quart... I just have a hard time putting Valv in my truck.

I think I may just get the OEM GM Dexron 6 from GM Parts Direct. It's pretty cheap, < $5/quart... and I believe a synthetic blend.

Shouldn't be this hard...
 
AMSOIL Synthetic Fuel Efficient Automatic Transmission Fluid is recommended for automatic transmissions and other applications requiring DEXRON® VI, MERCON® LV, SP or Toyota WS.

AMSOIL Synthetic Fuel Efficient Automatic Transmission Fluid is backward compatible and replaces DEXRON® III fluids in older GM automatic transmissions. (DEXRON® VI specification supersedes the obsolete DEXRON® III in GM vehicles.)
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That's what it says on their website, but it's never been tested or certified by GM to be used. Nor is Amsoil listed on the GM approved Dexron VI ATF list. :shrug: I have a hard time paying $10/quart for something that hasn't even gone through the basic testing and certification process... especially when I get the OEM fluid for less than half the price.

Redline is in the same boat....
 
Amsoil low viscosity fluid meets the dex VI spec. Amsoil ATF does not. The low viscosity fluid by amsoil was created in part to meet the dex VI standard, which their engineers tell me is difficult to meet at lower temperatures. It has been tested by independent testing facilities and it exceeds the standard set by GM.
All of the scientific oil testing standards recognized and used by all oil manufacturers are listed on their web site: amsoil.com
Purchasing the "certification" by GM is just a money grab by GM, and costs hundreds of thousands of dollars to purchase annually. Im sure Amsoil will grant GM the use of their name if they produce a product that meets their standard, and they pay them a few hundred thousand dollars per year.

Creating a "certification" is a trend you see with many manufacturers to pick up a % of oil sales, increasing their bottom line.
In the automotive industry alone, I can no longer keep track of haw many different spec's for transmission fluids there are. I have to look it up almost for each vehicle. Nissan has a half a dozen, honda has a few, toyotas, chrysler, form and gms all have differant specifications.
Just another note (from someone that studies transmission fluids) there are a few oil companies that claim to meet the dex VI specification, but if you read their fine print, they do not.
Here's one such example: http://www.epartsworld.com/SpecSheets/WHuniversalsynthetic.pdf
There disclaimer (located at the bottom of the page in fine print) : Some performance levels are limited by viscosity grades.
Another wards, it does not meet the spec.
My suggestion if your wanting to do it on the cheap is to buy the GM oil, and change it often. For most of my maintenance conscious customers, I install a drain plug in the pan and instruct my customers to drain and refill their fluid often, constantly diluting the dirty fluid into fresh fluid.
 
Thanks for the response.

Yea, I get the money grab issue - no doubt. A company like Amsoil probably doesn't do enough volume to be able to pay for those certifications and "sink" it into the product cost w/o dramatically increasing the price of their product, and possibly losing more customer based on cost. I get it. My concern is, that w/o that certification, it's basically a "trust us" model. :shrug: I don't know, I guess I'm just not that trusting! :)

I ordered 16 quarts of the GM Dexron VI tonight for $90 delivered ($5.62 per quart, synthetic blend).
14 quarts of the Amsoil ATL (low viscosity) delivered, even with the preferred pricing, would have been $151. ($10.78 quart)

I just can't justify the 1.5-2x factor of cost, plus no cert.

My 4L60-e trans pan seems to already have a drain plug in it, though I've heard they can be a real PITA to break free the first time (locktited). The truck has like 54k miles on it. I'm going to drain, drop the pan, replace the filter, re-bolt it up... refill, then use the "remove the upper trans cooler line" approach to replace all of the fluid (3-4 quarts at a time). After that, I think I can just periodically swap fluids (no filter replacement) every 30-50k.
 
The drain plug on your pan is made from a very soft metal and it strips very easily. Use a acetylene torch to heat it up before you attempt to remove it. Plan on going to the auto parts to buy a replacement. Depending on your vehicle you may need to remove your shifter cable bracket & transfercase mount bolts (if its a 4x4) and lift the t-case up to get enough clearance to remove the pan.
I would not suggest to remove a cooler line in attempt to pump fluid out. Starve the pump for oil and its possible to damage it. Stick with drain & refills. Start out with every engine oil change and after several changes start skipping a couple.
Manufacturers cannot specify what brand or certification of oil you must use unless they supply it to you for free. (That's part of a class action law suit from 15-20 years ago).
Manufacturers also do not release the "specifications" for the oils. Its up to oil companies to reverse engineer the oil through testing, and figure it out for themselves using standard oil testing procedures and chemical breakdowns.
There's a huge difference in the cost of producing PAO (poly-alpha-olefine) synthetic oils and Hydrocracked mineral based synthetic oils.
Outside of the USA, Hydrocracked oils can not be labeled as "Synthetic oil" as its method of production and materials used to produce it are not recognized as "Synthetic Oil" by any other country. (Another result of a class action law suite).
 
Detroit Gearbox said:
The drain plug on your pan is made from a very soft metal and it strips very easily. Use a acetylene torch to heat it up before you attempt to remove it. Plan on going to the auto parts to buy a replacement. Depending on your vehicle you may need to remove your shifter cable bracket & transfercase mount bolts (if its a 4x4) and lift the t-case up to get enough clearance to remove the pan.
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Thanks for the tip! It's a 2004 Tahoe Z71. Yea, everyone online has mentioned what a PITA that plug is. I'll definitely use that torch tip. I did order a GM replacement plug (was like $1). Should I just order an aftermarket pan ahead of time that has a drain plug... and just plan to abandon the stock one?


Detroit Gearbox said:
I would not suggest to remove a cooler line in attempt to pump fluid out. Starve the pump for oil and its possible to damage it. Stick with drain & refills. Start out with every engine oil change and after several changes start skipping a couple.
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Yea, I was a little nervous on this too. There a lot of people online who claim to have done this successfully... pumping 3-4 quarts out each time, refilling... 3 cycles. I was planning on shortening that to 2 quarts down, stopping the engine to refill, just to take more risk out. I don't want to flush it like with a BG machine, but I do want to replace most/all of the fluid. Do you think it's too risky even if I stop every 2 quarts I pull out?


On a separate note, I'm also going to replace the front and rear diff fluid. Any concerns going with the Amsoil 75W-90 Severe Gear fluid for both diffs? GM says any 75W-90 will work in the front, but they recommend their "grape juice" synthetic for the rear diff... and it's only available at the dealer for $26/quart (* 3). Was planning to just use Amsoil in both, and buy a replacement rear diff gasket too.
 
I would take the drain plug you get from the dealer to a auto parts and match it up. The thread is metric (12x1.75 I think) and it must have the wide oring that seals it. An aftermarket one from the auto parts will be a harder steel with a larger hex head and will last forever.
I'm not a fan of attempting to undo a cooler line. If your going to try it, over fill the transmission by 2-3 quarts before starting it. The pump will cavatate at 2 quarts low. 3 or 4 quarts low its sucking air.
The severe gear oil is actually a nice upgrade and substantially cheaper than the 80-90 synthetic gm recommended, but I use/stock both.
If your rear cover is rusted replace it. Its cheap.
Watch the front diff oil. Many times it looks like silver paint from having so much metal. If its loaded with metal change it again in 6k.
 
So, how about this...

I drain & drop the pan, change the filter, and rebolt it back up. To my understanding/reading, that will get ~4 quarts of fluid. So, then I refill with 7 quarts (or 3 more quarts than the amount that comes out). Take off the trans cooler line. Start the truck, pump out 3 quarts & then stop the engine (still 4 quarts in the pan - about normal level). Add 3 more quarts, repeat, pulling 3 more out. Add 3 more quarts, repeat, pull ~3 more out to where the correct fluid level should be. Reconnect trans cooler line to the radiator.

Does that plan sound fairly safe? There's no serious risk to the trans if I temporarily overfill it with 2-3 more quarts of fluid than normal (just to pump it out while in park)?
 
I'd rather do a drain plug drop every 3K till the fluid looked good. Just my opinion! Those 4L60's in my experiance are finicky.
 
Yea, after the guidance here, I think I'm going to error on the safe side and just do a filter replacement and replace whatever fluid was in the pan. Then, if I feel ambitious, I may drive it for a few miles, then re-drain and re-fill again, same day... or something like that.
 
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