Pep Boys Proline Dex 3/Merc tranny Fluid

Have any of you guys used the PepBoys store brand Dex3/Merc Tranny Fluid in your AW4? It is the only dex 3 marked fluid I can find locally.
Who Makes it?
Is it real Dex3?
Is it any good stuff or is it crap?

Thanks in advance!!

It has to meet the same quality standards, as established by GM, as any other Dex III labeled product.

I would say go for it.

The original licensed DEX III is no longer made. But as Joe said, any company that uses the DEX III marking on their product (by law) must be manufactured to the same spec. It will work just fine.

I've used Wally World tranny fluid through the years, and it's been fine. It's probably all made in the same factory anyway. Although, I'm picky about motor oil. Why one and not the other?

Dex III is no longer licensed for production, period, so anything that is called Dex III is whatever the vendor wants to label as a compatible fluid, which is usually whatever the accountants say is close enough to leave room for profit at $1 per bottle

garr said:

Have any of you guys used the PepBoys store brand Dex3/Merc Tranny Fluid in your AW4? !!

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yes! i am using it right now

garr said:

Who Makes it?

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warren performance packaging or warren distribution (same company)

i have been using it for years with no problems!

ehall said:

Dex III is no longer licensed for production, period, so anything that is called Dex III is whatever the vendor wants to label as a compatible fluid, which is usually whatever the accountants say is close enough to leave room for profit at $1 per bottle

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$1 per bottle? I wish!

It's $2.99Qt or $10.99 per gal container here in NY.

NAPA's Dex/Merc is the "Premium Performance ATF". Castrol has two varieties of Dex/Merc/Domestic multi-vehicle at Autism Zone (same product, different label). Couple of others at the various parts stores. Surely someone sells fluid for just about every mid 80s to late 90s GM, Ford, Toyota, or Chrysler vehicle in your area. Have to read the fine print on some of them.

I have used the Pep Boys Dex3/Merc without issue in my AW4.

hubs97xj said:

NAPA's Dex/Merc is the "Premium Performance ATF". Castrol has two varieties of Dex/Merc/Domestic multi-vehicle at Autism Zone (same product, different label). Couple of others at the various parts stores. Surely someone sells fluid for just about every mid 80s to late 90s GM, Ford, Toyota, or Chrysler vehicle in your area. Have to read the fine print on some of them.

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Yes, They all sell Dex4, That is supposed to be backwards compatable; But I have read here that Dex3 is the prefered Fluid for the AW4 so that is what I prefer to use.

Is Dex 4 truly backward compatable? Will it Hurt my AW4?

The current revision is Dex 6 ("VI"), and there has never been a publicly available Dex 4 ("IV"). Dexron VI was designed by GM to be compatible with all previous applications, just like Dex III was designed to be compatible with Dexron II. Maybe it isn't (Dexcool debacle broke that trust) but I have more confidence in their statement as designer than I do in the 'trust us' position of the so-called compatibles. I've been running it in my older Cadillac as well as my XJ for several years and they have taken to it really well, they run cooler and smoother than they did before.

Not all Dex IIIs are created equal. Some brands used to have a GM certification number on the bottle and that's the fluid you want to use. But since Dex III was discontinued, you won't find that anymore.

6K miles ago, I did new spark plugs (NGK), new serpentine belt, flush/fill of the t-case and flush/fill of the trans. I IMMEDIATELY noticed a roughly 3 mpg drop in my overall mpg, so I'm 99% sure it is due to one of those 4 things. I don't see how it could be the belt and I have already removed my CAI and went back to the stock intake with a new filter (just to see if that fixed it). Still have the problem. Next I am going to replace the plugs with regular Champions (because it's cheap and easy) and if that doesn't do it, I'm doing a second flush/fill on the AW4.

After looking around for a Dex III with the cert no. and having no success, the fluid I originally chose was Valvoline DEX/MERC ATF because it happened to be at the last store I visited. When my mpgs went down, I started investigating and that's when I found out about the discontinuation. I have since been told that Castrol's new Dex/Merc Domestic Multi-Vehicle ATF is the same as the old Dex III fluid that Castrol made, it's just been relabeled. That old fluid did have the cert no. So, Castrol's new stuff is the fluid I'll try next. If that doesn't bring back my mpgs, I guess I will have just wasted $50 or so and a few hours of my time...

Anyway, my point is, I would go with the Castrol stuff the first time... Just my $.02. Good luck.

ehall, did you notice any change in mileage when you went to Dex6? From what I have read, most Dex6 fluids are full synthethic or synthetic blends and and AW4 supposedly does not react well to those.

What brand did you use?

I read somewhere (can't find it at the moment, nor guarantee the accuracy) that the synthetics could prevent full engagement of the clutch pads- if I understood correctly, basically being too good a lubricant.

I'm starting the drain/fill cycle with mine, and am using the Castrol Dex/Merc Domestic Multi-vehicle. I haven't really paid attention to my mileage lately, but it does seem to be shifting firmer, and running a bit cooler, but I seriously doubt my fluid had ever been changed prior to this. Likely anything would have been an improvement.

Castrol changed the bottle/label, but the Dex/Merc Multi is the same product as before. Also specifically states not to use where Dex VI is called for, but they list their Dex VI as synthetic, and meeting or exceeding all Dex standards, FWIW.

Silly as it sounds, don't rule out the sparkplugs. Most folks on this site swear by Champs, and I've seen first hand why. My son tuned up his '95- was running fine, but was due. I forget what brand he put in, but it ran like crap. I said to get the Champs, he put them in, ran perfect. I would not have believed it if I hadn't seen it. Makes no sense. In mine, I've run Autolite Platinums from Wally World, and had excellent results. Those are the only two I could recommend.
Another point- what weight motor oil? 10-30 is recommended, but most 'newer' designed engines get a lot of their MPG gains from the lighter weight oils they use. I'm not sure our old 4.0s would like a steady diet of, say, 5-20. It may give you a few MPGs, but probably wear the engine out faster.

Well, Last night I hit pep boys & picked up 6 Gals of the Pro-line Dex3, I did one drain/fill last night drove 160mile round trip (Went fishing) with some Heavy Duty driving (On the beach) thrown in.
This morning I did another drain/fill, I plan on performing drain/fills every couple hundred miles until I complete 5 cycles, Then I will drop the pan & clean the screen & refill.
I will let you guys know hoe it works out.

PS: My AW4 has around 120K on it & I only performed a drain fill once at 95K. NO Issues to speak of, The tranny feels good.
Last night The fluid was dark but smelled ok, Today on the 2nd drain it looked redder!

gw204 said:

ehall, did you notice any change in mileage when you went to Dex6? From what I have read, most Dex6 fluids are full synthethic or synthetic blends and and AW4 supposedly does not react well to those.

What brand did you use?

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The only noticeable difference is smoother engagement and cooler temps (hand on tranny tunnel before and after change was difference of +20f).

As for brand they are 99% the same if they are produced under license, with the 1% being the vendor-specific additives. I use Pennzoil Dex VI for reasons I no longer remember.

ehall said:

The only noticeable difference is smoother engagement and cooler temps (hand on tranny tunnel before and after change was difference of +20f).

As for brand they are 99% the same if they are produced under license, with the 1% being the vendor-specific additives. I use Pennzoil Dex VI for reasons I no longer remember.

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Yep. Unlike motor oils, the formulas for automatic transmission fluids are developed by the auto manufacturers and production rights are licensed to the producers.

Synthetics are great, they reduce friction and stand up to heat better than dino.

So all of the gobeldeygoop crap about not running synthetics in the aw4 is just that? It won't hurt them? I'm not putting anything but dino in mine until I get a definite answer, which by the nature of an online forum may never happen.

Mr. mud said:

So all of the gobeldeygoop crap about not running synthetics in the aw4 is just that? It won't hurt them? I'm not putting anything but dino in mine until I get a definite answer, which by the nature of an online forum may never happen.

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It isn't an issue of synthetics in the AW4.

It is an issue of the formulation of the fluid used in the AW4.

Ok, quick run down--the Japanese AW4 was specified for Dextron III transmission fluid. You could not use the Chryco ATF +3 in the AW4.

Then along comes Chryco ATF +4, a much improved fluid. It was still not to be used in the AW4.

Magically, in 2006 Chryco determined that use of ATF +4 was good for the AW4. Also note that the magical moment happened after the AW4s were all out of warranty.

If you use Dextron III or Dextron IV you shouldn't have problems.

Some have reported problems with ATF +4, others swear it is second only to sex in giving them pleasure.

I have a theory. My theory is that if you get a really good flush of the AW4, getting all of the Dextron III out, you will have a chance of good luck with it. If you mix Dextron III and ATF +4, you will have problems. More of a WAG than a theory.

Again, no problems with synthetics, just make sure the one you use is the correct formulation.