Thinnest lubricant for this Manual Transmission?

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dx92beater

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I have a 93 Ford Escort GT with the "G Series" transmission.
The Protege LX of these years (can't remember exactly which years anymore) uses this transmission too.

I am trying to get the most MPG out of this car and want the thinnest possible lubricant in there amongst doing a few other things (eventually swapping out the 5th gear with a taller one).

Still looking at the original owners manual it called for "Motorcraft MERCON and DEXRON IIE Automatic Transmission Fluid". I know we are well beyond that these days. This car is my DD and it's next use will be commutes of about 140 miles a day.
 
Couldn't post anymore...just wanted to say that I know that lubricants are well beyond that requirement these days. Just analyzing this/doing this for fun.

The car is hardly ever beat on either.

Thanks for your time.
 
Dexron automatic transmission fluid is probably the thinnest fluid you can use in a manual transmission (one that specs it)! It's half the viscosity of something like a 90 weight gear oil. I believe it's around 6 Cst at 100C.
 
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Originally Posted By: Drew99GT
Dexron automatic transmission fluid is probably the thinnest fluid you can use in a manual transmission (one that specs it)! It's half the viscosity of something like a 90 weight gear oil. I believe it's around 6 Cst at 100C.


Hey Drew thanks!
 
hmmm filler or not, the transmission takes 3.55 quarts...I am too cheap for Redline (it's not my Galant VR-4).
smile.gif
 
Dex VI is GM's replacement for all previous Dexron fluids. It is at least semi synthetic, and is low visc for improved fuel mileage. All versions meet a chemistry spec and Super Tech is the lowest price.

There are a few applications that this low visc fluid doesn't hold up such as transfer cases, even though GM previously specced Dex III, they don't recommend Dex VI. If Dex VI isn't back specced for manual transmissions, use a synth for Dexron III applications such as Mobil 1 ATF or Transynd.
 
"ATF will be the thinnest ... but the far better manual trans syncromesh versions are not that much thicker."

+1

The best (for shifting and durability) would be an ATF-thin syncromesh fluid like Royal Purple Syncromax or Honda MTF II.

But they are not cheap. RP Syncromax will be $12+ per quart. You could shop around and try to find Honda MTF II at a discount ... might get it for $6-7 per quart if you look hard enough and/or are lucky.

You could run around and try to fine the thinnest ATF ... like the Red Line Oil product Molakule posted a link to ... but I'm not sure that a fraction of a cSt would give you even a tenth more MPG ... maybe just a couple hundreths.

I think BMW's ATF is also very thin ... something like 6.5 cSt while most others are in the 7s.
 
this is for a MT.. you cant use random lightweight ATF in it or you will have shifting issues. Redline makes specific products to make synchros happy. If you use a random one. you may be unhappy dumping it at 15$/qt
 
Try a 50/50 mix of Redline MTL70W80 and an ATF like D6.

This will give you the advantage of the AW and friction modifiers found in the MTL70W80 and a the ATF will lower the viscosity of the final fluid.

ATF by itself has little AW additives and no friction modifiers for synchro assemblies.
 
Originally Posted By: ledslinger
Dex VI is GM's replacement for all previous Dexron fluids. It is at least semi synthetic, and is low visc for improved fuel mileage. All versions meet a chemistry spec and Super Tech is the lowest price.

There are a few applications that this low visc fluid doesn't hold up such as transfer cases, even though GM previously specced Dex III, they don't recommend Dex VI. If Dex VI isn't back specced for manual transmissions, use a synth for Dexron III applications such as Mobil 1 ATF or Transynd.


They specifically tell you NOT to use the Dex 6 in the Tremec T56es and 6060s!
 
Originally Posted By: MolaKule
Try a 50/50 mix of Redline MTL70W80 and an ATF like D6.

This will give you the advantage of the AW and friction modifiers found in the MTL70W80 and a the ATF will lower the viscosity of the final fluid.

ATF by itself has little AW additives and no friction modifiers for synchro assemblies.


^^^GREAT idea!
thumbsup2.gif
(If he wants to spend the coin).

That RL racing ATF is WAAAYYY too thin for for a manual at 4.9 cSt (besides having the lack of AW and FM additives found in the MTL or similar fluids from other companies).
 
You all are awesome. I love being able to have this much fun. It should be illegal.

Thank you!
smile.gif
 
Hard to understand why Dex VI wouldnt work.Does that mean that Merc V won't work? My 88 Ranger had ATF in the Transfer Case and transmission. I used Merc, Dex and Amsoil in it. No difference. I seriously doubt if one ATF over another would even microscopically change mileage.

I wouldn't be choosy what goes in there..personally
 
I drive a 94 Mazda MX6 5spd. I am not sure how similar my transaxle is to yours but it shares a lot of history with other cars around then and also spec'd Dex-II/III ATF fluid and only holds a 2.7 for a refill (I imagine a new fill is more in your range).

First gear can be notchy shifting into it, be it from a stop or a roll, especially the first 1-2 shifts. It does this no matter what the fluid.

Anyway, I've tried running 3 different types of fluid, here are the results:

Fluid #1) Mixture of Redline MTX and the Redline MT-90 gear oils. Shifted nicely but wasn't a miracle fluid that made shifting into 1st perfect like I thought it would. This was the smoothest mixture but not really worth it probably unless you live in Canada or something.

Fluid #2) 100% Pennzoil Synchromesh - Not bad but not all that great either to be honest. First shift or two of the day can grind, this is pretty common on my car. Comes out of the bottle like water, even thinner than ATF. Engagement not quite as smooth and quick like I remember with Redline.

Fluid #3) Mixture 60% Castrol ATF for Import Vehicles (meets sooo many things, even Honda ZR-1 just like Maxlife but cheaper, meets Dex II/III) + 20% AutoZone Generic Dex/Merc ATF (meets Dex II/III but NOT DEX VI ) + 20% Valvoline Maxlife Dex/Merc (meets everything including Dex II/III) . Overall this works just like I remember Redline did!. FAST shifts, positive feeling of engagement. First shift or two into first still grinds mildly, pretty normal for my car. It is a fresh fill so only time will tell how long it will last before I have to change it due to shearing.

Bear in mind I life in fairly mild climates, I am only seeing about 25 degrees F as a low usually.
 
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senquack -
Now that you have eliminated the anti wear and extreme pressure additives by using ATF, is it worth it?
 
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