Manual Trans Fluid Question

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daemontrym

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I know I have beaten to death questions about my 2012 Kia Forte's 6spd notchy trans..
My car currently specs for GL4 75w85..

After many searches here and in other forums it seems that moving to a dedicated synchromesh MTF is a good idea. I have read threads in mitsubishi, subaru, hyundai, and GM forums where using this type of MTF dramatically improved shifting in all conditions. Plus in my last post some suggested what I have is a friction modifier problem rather than that of viscosity.

So my main question is would going to a synchromesh style MTF cause premature wear on my transmission? The difference in weight is negligible like 70/75w80 vs the speced 75w85.
 
No, just go to a quality syn like Amsoil which Ive found to be the best. Youll be happy.
 
You say your car specs 75w-85 GL-4. Do you have a GL-4 fluid in the car now?


I would NOT go to a thin synchromesh fluid like Pennzoil.

The only one I might try is the Valvoline Synchromesh MTF which has a viscosity that matches your gear oil weights.

Whatever you do....DO NOT use a GL-5 that is NOT yellow metal safe.

I might suggest Pentosin MTL 2 which is 75w or
Amsoil Manual Transmission & Transaxle Gear Lube 75W-90.

Both these fluids are GL-4 so they have the correct chemistry for yellow metals and moderate pressures demonstrated by synchronized gear boxes.
 
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If your MT transmission specs a 75W85, the manf. wanted a 12.0 cSt Kinematic Viscosity lubricant:

Such a lubricant is the Redline MT-85 75W85 GL-4 Gear Oil and specs can be seen at:

Redline 75W85 specs

However, going down in viscosity to 10 cSt to a fluid such as Amsoil

Amsoil 9.7 cSt

or Redline

Redline 10 cSt

or

Pennzoil Synchromesh

may improve shifting but not necessarily increase wear.
 
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Originally Posted By: default
See what it specs outside of CAFE land, might work better with a 90 weight, like Redline MT90.


Odds are it is spec'd for something thinner outside the USA.
 
The OEM fluid is a full synthetic 75w85 MTL. Make sure that any fluid that is installed complies with the warranty standards. Stay with 75w85 MTL. Try Nissan's, Honda's, or an aftermarket like Redline.
It will be difficult to change the shifting feel through fluid. It is the nature of the transmission. You'll have to get used to it. The gearbox was built for economy, not sport.
 
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Originally Posted By: salv

It will be difficult to change the shifting feel through fluid. It is the nature of the transmission. You'll have to get used to it. The gearbox was built for economy, not sport.


I disagree. I changed the shift feel of the transmission in my Cruze for the better by putting in Amsoil Synchromesh. In my case, the OEM fluid is a 70w fluid, so it worked out well viscosity-wise.

Give a quality aftermarket full synthetic fluid a go.
 
Originally Posted By: sciphi
Originally Posted By: salv

It will be difficult to change the shifting feel through fluid. It is the nature of the transmission. You'll have to get used to it. The gearbox was built for economy, not sport.


I disagree. I changed the shift feel of the transmission in my Cruze for the better by putting in Amsoil Synchromesh. In my case, the OEM fluid is a 70w fluid, so it worked out well viscosity-wise.

Give a quality aftermarket full synthetic fluid a go.


You went from a conventional synchromesh to a synthetic synchromesh style MTL. The Kia already has a full synthetic MTL. Being that the vehicle is under warranty I would not advise deviating from the type of MTL that the gearbox comes filled with. It is very high quality and is intended to be a "lifetime" fill with severe service change at 60k.
 
Quote:
So my main question is would going to a synchromesh style MTF cause premature wear on my transmission? The difference in weight is negligible like 70/75w80 vs the speced 75w85.


A dedicated or Application Specific Manual Transmission lubricant will always perform better than a common differential fluid of the same viscosity because it is designed specifically for the proper engagement of a synchromesh gear train.

Overall, wear should be less with a dedicated or Application Specific Manual Transmission lubricant or MTF.

The difference in viscosity of the fluids you mentioned maybe unnoticeable in terms of shift performance.
 
Pentosin MTF2 is considered a 75w80 just like the rest of the MTL's/MTF.
According to redline's website both MTL and MT85 are considered a 5w30. MTL is 10.6CST, MT85 is 12, and the Castrol Syntorq is 11.1.

I might try to go back to OEM now that the trans is broken in some.
But, at low mileage it was extremely notchy and I could see the shifter visibly shake when in gear. When I switched to MTG and the castrol Syntorq it stopped doing that completely. Thats why I don't have a lot of faith in the OEM fluid. It could of just been loosening up as it was getting broken in.

I know Pentosin MTF 2 is FF on many german cars that spec 75w90 in everything else. My 08 VW rabbit I had was flawless.
 
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I almost forgot that your Kia is still under factory warranty.

I agree with others here, perhaps you should just buy new OEM fluid (which is full synthetic) and install it...

Also like others have said, perhaps you need to have the rod or cable adjusted properly, the question is can you find a competent Kia tech you trust to work on it. If you are not happy see if you can find a used model identical to yours on the lot and test drive to see if indeed they are "all like that". If so you have to live with it, if not they can properly adjust your cable or rod to engage the gears properly. I also wonder if your clutch is working properly?

That being said, I just don't trust the Korean brands yet. I have heard less than wonderful things about their manual gear boxes as well.

I see you had a Golf/Rabbit from 08..why did you get rid of it?
They are WONDERFUL cars, great handling, comfortable, with excellent reliability and made in Germany too.


Pentosin MTF 2 is GREAT stuff. VW does use it as OEM on certain models from time to time. They have a number of vendors for manual gearbox oil. Pentosin, Shell, Esso, Castrol, and I think one or two others.
 
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I loved the VW but had to get rid of it once becoming a full time student as I left Ft. Campbell.

I am positive that the rod and shift cables are not the problem. I had that problem on one of the fieros and quickly fixed it.

I see on the Pentosin website they list MTF 2 for the Hyundai Genesis which uses the same fluid as my Kia. So that is giving me some food for thought being a "warranty" approved oil.

Another one that grabs me from some more looking is Motul Gear 300 because of being a high VI 75w90, but what scares me is being a dual rated GL4/GL5.
 
Originally Posted By: daemontrym
...

I know Pentosin MTF 2 is FF on many german cars that spec 75w90 in everything else. My 08 VW rabbit I had was flawless.




Just to clarify, Pentosin MTF2 is FF or similar to factory fills in cars that DO spec 75W-90. Don't ask me why. It makes no sense to me to call out 75W-90 but then throw in 6 cSt @100C fluids in at the factory.
 
I think the 2 things that cause kia forte man trans drivers grief is an abrupt throttle by wire tune and lack of clutch feel. By taking out the delay valve shifting was markedly better than with it. The tune for the throttle pedal has a few second delay before the RPMs begin to rise very quickly. Because, of the delay you cannot modulate it very well and it is almost like an on off switch rather than a throttle. Built inside the plate on top must be a potentiometer of some sort. Because, if you loosen the screws and push the slots toward the firewall the delay goes away but the pedal is much much more sensitive. If you move the slots toward the rear of the car the delay is much longer and much more travel is needed to get moving. I think if they worked out a better tune with the throttle by wire 90% of the bad reviews they get for manuals would be much better.


I love everything about my kia and believe it is a quality car with only 1 fault stated in this thread.

So far I have tried OEM, AMSoil MTG, and currently have in Castrol Syntorq 75w85 that I purchased from a dodge dealership. OEM was horrible and felt like I had canola oil in the trans. AMSoil MTG felt good but felt like there was a bigger wall in between each gear shift. The castrol is better than AMSoil MTG, but in hot weather once warmed up shifting starts to feel like OEM.

Thats why my hunt continues because I have owned many high mileage stick cars that speced either synchromesh or ATF and they worked great under all conditions. Thats what has me thinking that this is a FM problem rather than viscosity. Molakule suggested the same when I posted my last thread about being a Kia man trans diva.
 
Did you see my other post where I suggested that you look for a used model of your car on a dealer lot and take it for a test drive to determine whether it is a designed in quality or not?

I have a feeling that at least part of the problem is that the design is not a good one.

Remember that Kia is not VW, they are a seeking buyers from the Toyota, camp and as you know folks that buy Toyota don't look for a finely tuned ride, just basic A to B transportation.

I still would give the Pentosin MTF2 a try.

Oh, one more thing DO NOT use a dual rated gear oil even if it dual GL-5/GL-4 you cannot be adequately certain that the fluid might be too slick or too corrosive to your trans axle parts.
 
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Just to throw some more fuel in the fire This is a link to a TSB changing OEM 75w85 to Pentosin MTF2 for the hyundai genesis.

http://www.myhyundaiforums.com/10-01-039.pdf

Pentosin now has an OEM part number on their website for hyundai. I am wondering if this campaign will trickle down to most of their line up.

So I am wondering if this would create a valid question to ask the service manager there.

What would you guys think? Try something thinner or put in a 50/50 AMSoil MTF/MTG mix? I have done a lot of reading on redline vs amsoil and many who have run both prefer AMSoil.
 
Motorcraft XT-M5-QS. It's rated as a GL4 75-90 but seems actually quite thin- would probably work wonders in your car. Sure did in my Mazdaspeed 3. It has a VI of 212 IIRC and it's great stuff.

Just google it and see if any Kias are using it. It is made in Germany. I just bought a 2013 MS3 and it'll be getting it shortly......
 
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