Early93Viper
Enthusiast
Tranny fluid is Dextron 4 or 3 better for a GEN I Tranny? 
Dextron 4 VS Dextron 3
- Thread starter Early93Viper
- Start date
The Dexron product line sold under the Mopar name(Dexron II-E for 92-96, and Dexron III for 97-98)is no longer available at dealerships.
As stated on page 40 of the Spring 2008 issue of Viper Magazine, Mopar's ATF+4 Automatic Transmission Fluid is the recommended replacement for the Dexron fluids. Note per a TSB from May 1998, one CAN use Mopar's Synthetic Manual Transmission Lubricant 75W-85 for the purpose of treating Neutral Gear Rattle in 94-98 Vipers...BUT NOT in 92-93 Vipers.
Hope this helps!!!
As stated on page 40 of the Spring 2008 issue of Viper Magazine, Mopar's ATF+4 Automatic Transmission Fluid is the recommended replacement for the Dexron fluids. Note per a TSB from May 1998, one CAN use Mopar's Synthetic Manual Transmission Lubricant 75W-85 for the purpose of treating Neutral Gear Rattle in 94-98 Vipers...BUT NOT in 92-93 Vipers.
Hope this helps!!!
Tom F&L GoR
Enthusiast
Generally lubricant upgrades are backward compatible; newer oils work in older cars.
Two things to note, however.
1) Newer engine oils contain less zinc-phosphorus anti-wear additives to protect the catalyst and are OK for new engines (with roller lifters) and old cars (that are broken in) but not good for newly rebuilt engines with sliding lifters. Use a break-in oil, motorcycle oil, or diesel oil.
2) Gear oil nomenclature is not sequential. GL-5 is not better than GL-4, they are just different for different applications. Example - the Castrol Syntorq and GM/Mopar equivalents is GL-4, but do not use a GL-5 oil in your T-56.
Two things to note, however.
1) Newer engine oils contain less zinc-phosphorus anti-wear additives to protect the catalyst and are OK for new engines (with roller lifters) and old cars (that are broken in) but not good for newly rebuilt engines with sliding lifters. Use a break-in oil, motorcycle oil, or diesel oil.
2) Gear oil nomenclature is not sequential. GL-5 is not better than GL-4, they are just different for different applications. Example - the Castrol Syntorq and GM/Mopar equivalents is GL-4, but do not use a GL-5 oil in your T-56.
Early93Viper
Enthusiast
The real answer is...I don't know...ask Tom.
My opinion is NO!!
Sorry that I don't have my 1993 Service Manual with me at the coffee shop today...but from the 1995 Viper Service Manual...''...T-56...uses...Dexron II-E. This new fluid can withstand higher temperatures than standard Dexron II, Mercon or Mopar 7176 fluid. The use of standard Dexron II, Mercon or Mopar 7176 automatic transmission fluid is not recommended''.
Good luck.
My opinion is NO!!
Sorry that I don't have my 1993 Service Manual with me at the coffee shop today...but from the 1995 Viper Service Manual...''...T-56...uses...Dexron II-E. This new fluid can withstand higher temperatures than standard Dexron II, Mercon or Mopar 7176 fluid. The use of standard Dexron II, Mercon or Mopar 7176 automatic transmission fluid is not recommended''.
Good luck.
Tom F&L GoR
Enthusiast
My opinion is ... I don't know.
Historically the big difference between Dexron and Mercon fluids was that GM and Ford wanted very different frictional properties from the fluids so that the automatic transmission provided the shift qualities the engineers wanted. As you can imagine, a "harsh" mechanical system might want a highly friction modified fluid and a "gentle" mechanical system would like a low or non-friction modified fluid.
Completely separate is the ability to withstand high temperatures. The base oil choice and the amount of anti-oxidants added determined how hot and for how long the automatic transmission fluid could run. The engineers might want to decrease the size of the ATF heat exchanger for cost and weight savings, so fluid would run hotter... all this would be built into the Dexron or Mercon specifications.
And we have a manual transmission, so there's another step away from what the fluid is really designed for. (I know, Dexron was specified in Vipers since 1992, but that came about because testing showed it was OK, not that the fluid development testing targeted good performance in a T-56.)
So what to do? Well, I get confused beginning with comment #1 above - how a fluid meets generally high friction and generally low friction requirements for the two ATF applications at the same time. In the marketing world of having a one-size-fits-all product, it makes me suspicious.
The good news is that the high temperature capabilities should be good - it meets higher specs.
What to do? Monitor the shift quality when the fluid is hot and here's the hard part - mark on the calendar in a month or two, to "evaluate" shift quality again. We don't know if having high, low, or medium frictional characteristics from an ATF is best for a T-56.
I know I'm rambling. I think no matter what, there will be no "bad" effects. It just may not shift like you want, and if not, you'll have to change it again. So try it and see.
Historically the big difference between Dexron and Mercon fluids was that GM and Ford wanted very different frictional properties from the fluids so that the automatic transmission provided the shift qualities the engineers wanted. As you can imagine, a "harsh" mechanical system might want a highly friction modified fluid and a "gentle" mechanical system would like a low or non-friction modified fluid.
Completely separate is the ability to withstand high temperatures. The base oil choice and the amount of anti-oxidants added determined how hot and for how long the automatic transmission fluid could run. The engineers might want to decrease the size of the ATF heat exchanger for cost and weight savings, so fluid would run hotter... all this would be built into the Dexron or Mercon specifications.
And we have a manual transmission, so there's another step away from what the fluid is really designed for. (I know, Dexron was specified in Vipers since 1992, but that came about because testing showed it was OK, not that the fluid development testing targeted good performance in a T-56.)
So what to do? Well, I get confused beginning with comment #1 above - how a fluid meets generally high friction and generally low friction requirements for the two ATF applications at the same time. In the marketing world of having a one-size-fits-all product, it makes me suspicious.
The good news is that the high temperature capabilities should be good - it meets higher specs.
What to do? Monitor the shift quality when the fluid is hot and here's the hard part - mark on the calendar in a month or two, to "evaluate" shift quality again. We don't know if having high, low, or medium frictional characteristics from an ATF is best for a T-56.
I know I'm rambling. I think no matter what, there will be no "bad" effects. It just may not shift like you want, and if not, you'll have to change it again. So try it and see.
Thanks, Tom...always good info!!
Well, I'm back home now...so I checked the 1993 Manual...which gave the same warning...and an added warning against hyphoid gear lube.
I remember calling Tom several years when Wife's favorite got a batch of the then new ATF +4 installed in the tranny because the parts guy thought that ''a 4 of anything had to be better than a 3''...never mind different product family...and one with a Roman III and the other an Arabic 3.
In that case, I personally changed that Gen I Viper back to Dexron III and had no problems. Better safe than sorry in my book!!
NOW, several years later, I find out that the ATF+4 IS the APPROVED fluid that superceeds the Dexron line for 92-98 Vipers.
Live and learn !!
Well, I'm back home now...so I checked the 1993 Manual...which gave the same warning...and an added warning against hyphoid gear lube.
I remember calling Tom several years when Wife's favorite got a batch of the then new ATF +4 installed in the tranny because the parts guy thought that ''a 4 of anything had to be better than a 3''...never mind different product family...and one with a Roman III and the other an Arabic 3.
In that case, I personally changed that Gen I Viper back to Dexron III and had no problems. Better safe than sorry in my book!!
NOW, several years later, I find out that the ATF+4 IS the APPROVED fluid that superceeds the Dexron line for 92-98 Vipers.
Live and learn !!
I had time to review the specs and claims by Valvoline on this product...and in the applications they list, it looks like this product could be used as a Dexron II-E and Dexron III substitute ...though I saw nothing specific to manual transmissions (let alone the T-56's used in the early Vipers ...92 and 93... which seem to have some more-than-normal vulnerable components). Admittedly, I don't like to gamble with pieces of equipment such as Vipers...so hopefully you can trust Valvoline.
Early93Viper
Enthusiast
Thanks Tom, and all others that posted. It runs fine now. I guess I will find out at viper days next weekend if it's ok.
You can't find DEXTRON III anymore. I have talked to many mechanics and they say this DEX/ MERC has replaced it.
You can't find DEXTRON III anymore. I have talked to many mechanics and they say this DEX/ MERC has replaced it.
TexasPettey
Enthusiast
Given that you track it, why not run synthetic 75W90 gear lube?
Tom F&L GoR
Enthusiast
no, no, you mean GL-4. GL-5 is too aggressive chemistry.
Please remember that in several instances that we have been warned not to use gear lube in 1992/3 RT/10 transmissions as the lubricant is too aggressive toward the synchronizer material. The 2nd post at the top reiterated that concern.
TexasPettey
Enthusiast
Sorry, I was thinking of the Castrol Syntorqe. I also didn't realize that '92/'93 was different than other Gen1's.
'' I also didn't realize that '92/'93 was different than other Gen1's.''
When one of our sharpest members...Ron... saw the Tranny TSB mentioned above, HE noted that the Castrol Syntorq was NOT recommended for 92's and 93's (by exclusion).
So, Ron tracked down some old Borg-Warner folks and confirmed what Dodge already knew!!
When one of our sharpest members...Ron... saw the Tranny TSB mentioned above, HE noted that the Castrol Syntorq was NOT recommended for 92's and 93's (by exclusion).
So, Ron tracked down some old Borg-Warner folks and confirmed what Dodge already knew!!
TexasPettey
Enthusiast
For the cars that can use 75W90, would a lube that states multiple GL statements work? As an example, these all state use in GL-4 & GL-5 applications. Although the Mobile1 only states GL-5 classification. Interesting that I can't find the Castrol Syntorq on their website. The Castrol Syntec 75W90 is a GL-5 per the bottle.
Mobil 1 Synthetic Gear Lubricant LS 75W-90
PX3 Lubricants :: Synthetics on Steriods
Royal Purple Gear Oil
Tom F&L GoR
Enthusiast
The difference in design criteria is that the GL-5 is designed for heavily loaded differentials. Usually GL-5 is also MT-1, which is non-synchro transmissions.
API GL-5 Clearing up the confusion - Products - Lubrizol Automotive Gear Oil Additives
Pennzoil sells two 75W-90 oils, one is GL-4 and other is GL-5. You'd think they would know how to make only one, huh?
Products - Synthetic Gear Oils 75W-90
The story you'll hear is that GL-5 is "better" because it has more additives. These additives (for hypoid gears) are extremely aggressive and will corrode yellow metals (brass, bronze, copper = synchros). So to be GL-4 and GL-5, the marketer has to meet GL-5 performance and GL-4 corrosion tests, meaning they will say they have more special, expensive versions of the additive that are high performance but low corrosivity.
In other words, to be good at GL-5 it has to be "aggressive" and to be GL-4 it is "not too aggressive". If SAE had wanted it that way, they could have built all that into the specs...
When it comes to gear oils and transmission oils, the OEMs test them as if they were fill for life (because often they are anyway.) I'm not as adventurous and stay closer to their recommendations.
The Castrol for T-56 is Syntorq LT 75W-85W (yes, two W's) and not Syntech.
API GL-5 Clearing up the confusion - Products - Lubrizol Automotive Gear Oil Additives
Pennzoil sells two 75W-90 oils, one is GL-4 and other is GL-5. You'd think they would know how to make only one, huh?
Products - Synthetic Gear Oils 75W-90
The story you'll hear is that GL-5 is "better" because it has more additives. These additives (for hypoid gears) are extremely aggressive and will corrode yellow metals (brass, bronze, copper = synchros). So to be GL-4 and GL-5, the marketer has to meet GL-5 performance and GL-4 corrosion tests, meaning they will say they have more special, expensive versions of the additive that are high performance but low corrosivity.
In other words, to be good at GL-5 it has to be "aggressive" and to be GL-4 it is "not too aggressive". If SAE had wanted it that way, they could have built all that into the specs...
When it comes to gear oils and transmission oils, the OEMs test them as if they were fill for life (because often they are anyway.) I'm not as adventurous and stay closer to their recommendations.
The Castrol for T-56 is Syntorq LT 75W-85W (yes, two W's) and not Syntech.
