2019 GT1 RWD rear diff fluid change

[D.J.]

Does anyone know the socket sizes for the rear diff fill and drain plugs? The biggest I have is 22mm and it's a bit bigger than that.

Pretty sure it's 24mm

 

[josh2112]

Just to note, that was the same fluid I used, but I still had some audible binding in the diff when making turns, I ended up having to drain some fluid and added some LSD (Limited Slip Differential) additive to correct it. Another user posted that using the Royal Purple gear oil worked without having to include any additive, but I'm not sure if that car had an LSD (Limited Slip Differential).

I'm going to need some of that additive...

I swapped out my fluid over the weekend for the Valvoline 75w-90 (same as in @D.J. 's earlier post) and I'm also now getting the popping and humming when applying power while making sharp turns (e.g. navigating a parking lot).

If the additive doesn't work I'll try the Redline oil mentioned by @Rodtheviking

 

[josh2112]

Alright. I need some help sorting out this information. And I'm apparently too new to post images or links, so sorry...

Issue: The Valvoline 75W-90 causes popping and grinding where there was none before.

@escblads reports he's had success with the Valvoline plus a bottle of Trans-X Posi-Trac LSD additive.

Some other oils mentioned are Redline GL-5 75W-85, Royal Purple 75W-90 and Amsoil 75W-90. Neither of these users mentioned any noises but I don't know if we've had any long-term updates on that.

A technical service bulletin from KIA mentions the "abnormal rear differential noise of rrrrrrr" (lol) and specifies the oil be replaced with "SK HK JL Syn LSD Gear Oil 75W85 PLUS" with a part number of 02100-00121. This oil is supposed to have "friction modifiers" in it to reduce noise. The remarks are that old oil is 3.5% friction modifiers and the new oil is 7%.

Googling this part number gets you a blue bottle with a black label which has the "PLUS" (along with "GL-5" prominently on the label. But there's apparently no way to buy this oil outside of South Korea.

I have seen an "equivalent North American" part number of UM017 CH126. Googling that gets you a distinctly different bottle, black with a gray label, that does mention the friction modifiers on the back but doesn't have a "PLUS" on the front. I suspect this might be the previous oil that KIA no longer recommends?

What's the recommendation here:
- Keep the Valvoline and try the additive?
- Swap it out for the Royal Purple or Redline?
- Get the UM017 CH126 from a dealer?
- Option 4...?

 

[Rodtheviking]

Just did mine too, I used Lucas Synth 75W-90 and no noise at all, nice and smooth.

Nobody had Redline near me so went with Lucas as I have used it in the past and always worked well.

I would drain and fill with something else. I have always heard of issues with Valvoline so I personally wouldn't use it.

 

[josh2112]

Just did mine too, I used Lucas Synth 75W-90 and no noise at all, nice and smooth.

Nobody had Redline near me so went with Lucas as I have used it in the past and always worked well.

I would drain and fill with something else. I have always heard of issues with Valvoline so I personally wouldn't use it.

EDIT: never mind, didn't read full post

On a whim I bought the "official" KIA 75W-85, part number UM017 CH126. My fluid came out nice and clear with no graphite and no smell of sulfur, so suspect the dealer changed it 18 months ago at 12k miles before I bought the car. Undoubtedly that's what they put in it. And I never got any binding or growling before.

 

[Rodtheviking]

EDIT: never mind, didn't read full post

On a whim I bought the "official" KIA 75W-85, part number UM017 CH126. My fluid came out nice and clear with no graphite and no smell of sulfur, so suspect the dealer changed it 18 months ago at 12k miles before I bought the car. Undoubtedly that's what they put in it. And I never got any binding or growling before.

Not in the Stinger, I have it in my Tundra.

 

[josh2112]

Not in the Stinger, I have it in my Tundra.

Well I'm not sure how knowing what you have in your Tundra is going to help me with my Stinger bud

UPDATE

I went with the path of least resistance, which was keeping the Valvoline already in there and adding a tube of the TransX Posi-Track. It did indeed fix the popping noises right away.

The Trans-X tube is 7 oz. I cracked open the rear diff drain plug and *very carefully* unscrewed it till fluid just started dribbling out. Once I had about a cupful out I re-tightened it, then squeezed the tube of additive into the fill hole, then topped it off with my leftover Valvoline 75W-90. The first 'test' at the stop sign below my house showed an immediate difference -- no more popping noise or feeling from the rear diff.

 

[Rodtheviking]

It's a differential, bud.

 

[Rynil2000]

I am preparing for the 36K mile service. They grow up so fast.

Per the KGIS service manual:





I plan on using a couple quarts of Red LIne 50104 75W85 GL-5. It seems to have good reviews, the correct viscosity, and LSD additives. I wish it came in one of those nifty Valvoline bags, but I've got a Hazard Fraught hand pump from over-filling the oil once, so all good there.

Anyone have experience or feedback with using this gear oil?

 

[Ohiocruiser]

I am preparing for the 36K mile service. They grow up so fast.

Per the KGIS service manual:

View attachment 76190
View attachment 76191
View attachment 76192

I plan on using a couple quarts of Red LIne 50104 75W85 GL-5. It seems to have good reviews, the correct viscosity, and LSD (Limited Slip Differential) additives. I wish it came in one of those nifty Valvoline bags, but I've got a Hazard Fraught hand pump from over-filling the oil once, so all good there.

Anyone have experience or feedback with using this gear oil?

That's what I've been using. Redline 75w85. No complaints.

 

[djerickd]

where's the cheapest place to get the UM017 CH126 online and delivered? I have found $40 shipped from Genuine OEM Kia Parts and Accessories Online - Kia Parts Now

 

[Rynil2000]

where's the cheapest place to get the UM017 CH126 online and delivered? I have found $40 shipped from Genuine OEM Kia Parts and Accessories Online - Kia Parts Now

$40 doesn't seem like a bad price for OEM "parts". I Googled the part number and had a local dealer come up so it may be able to be purchased through your dealer's parts counter.

Also, if you have the LSD, you're going to want the LSD Gear Oil Syn PLUS (GL-5) SAE 75W85, which is part number 02100-00121. This change is mentioned in a 2018 TSB.

Thanks for the part number and good to hear the Redline is working out. Now decisions, decisions...

 

[djerickd]

aww shoot

 

[AWDGT2]

This should help, I did it last year

 

[djerickd]

$40 doesn't seem like a bad price for OEM "parts". I Googled the part number and had a local dealer come up so it may be able to be purchased through your dealer's parts counter.

Also, if you have the LSD (Limited Slip Differential), you're going to want the LSD (Limited Slip Differential) Gear Oil Syn PLUS (GL-5) SAE 75W85, which is part number 02100-00121. This change is mentioned in a 2018 TSB.

Thanks for the part number and good to hear the Redline is working out. Now decisions, decisions...

I can't seem to find 02100-00121 in the USA. Like I can with UM017 CH126 that is easily available and says it's for LSD (I found these pics online):

 

[Rynil2000]

I can't seem to find 02100-00121 in the USA. Like I can with UM017 CH126 that is easily available and says it's for LSD (Limited Slip Differential) (I found these pics online):

View attachment 76198View attachment 76199

Here's the TSB info I found on a separate thread.

Take it back ASAP, this is what they should have put in it.
View attachment 36362

That's what I've been using. Redline 75w85. No complaints.

Says you should be looking for the "PLUS" oil. Both are LSD 75W85, but I believe the plus may have added friction modifiers. It seems those can be added after the fact, also. But I'm no expert if anyone wants to chime in.

 

[Rynil2000]

Here's the TSB info I found on a separate thread.




Says you should be looking for the "PLUS" oil. Both are LSD (Limited Slip Differential) 75W85, but I believe the plus may have added friction modifiers. It seems those can be added after the fact, also. But I'm no expert if anyone wants to chime in.

@djerickd For reference, here is the picture of "PLUS" oil I saw over on the Genesis forum. Link to G70 forum thread.

 

[djerickd]

I really can't seem to find that blue bottle for purchase, can someone link me?? That must be the new stuff because my order for the black bottles was cancelled on me. "ordered part(s) have been discontinued (no longer available) and/or is backordered with no ETA date by the manufacture"

 

[Rynil2000]

I am preparing for the 36K mile service. They grow up so fast.

Per the KGIS service manual:

View attachment 76190
View attachment 76191
View attachment 76192

I plan on using a couple quarts of Red LIne 50104 75W85 GL-5. It seems to have good reviews, the correct viscosity, and LSD (Limited Slip Differential) additives. I wish it came in one of those nifty Valvoline bags, but I've got a Hazard Fraught hand pump from over-filling the oil once, so all good there.

Anyone have experience or feedback with using this gear oil?

Well, I replaced my LSD differential oil with the Redline 75W85 GL-5 oil and now I am experiencing a light shudder/vibration from the rear when reversing or turning when cold. As the car warms up, the shudder goes away and there isn't an issue.

@josh2112 Are you still satisfied with the results after using the Trans-X Posi Trac LSD Additive? Any more shudder or "rrrrrr"?

@djerickd Did you ever track down the Kia UM017 CH126 diff oil? Did you change over to this oil. I would be interested to hear any feedback if so.

 

[josh2112]

@josh2112 Are you still satisfied with the results after using the Trans-X Posi Trac LSD (Limited Slip Differential) Additive? Any more shudder or "rrrrrr"?

I have to say I do occasionally get the noise when turning sharply from a dead stop. It's not as bad as with the Valvoline gear oil alone, but it's definitely something I didn't hear with whatever fluid was in there before :-/