Differential oil and additive for LSD

[joegr]

Mine doesn't have LSD. Or at least it doesn't say on the window sticker, so doubt it has it, since it's a 4 banger. So which fluid for the non-LSD? Thx.

From your owner's manual (page 2-13):

 

[yostrovsky]

Mine doesn't have LSD. Or at least it doesn't say on the window sticker, so doubt it has it, since it's a 4 banger. So which fluid for the non-LSD? Thx.

I would suggest whatever oil listed in manual. (see post above).
For not LSD differential it may be not so important, but it's better to follow a car manual.
I learned it by my mistake.

 

[tompass]

Quick Reference Guide sAttach fileshows only to inspect LSD oil. Very confusing.

 

[Slip_Angle]

If you have LSD use ONLY 75/85.
No additive needed.

My diff was replaced. The new one is using the Genesis oil and started making noise. I'm starting to wonder if the oil needs *more* friction modifier? It's also colder here.. -15 to 0 celcius. Maybe the oil is too thick in this cold?? Something a friction modifier would help I think.

 

[tompass]

I used the redline with FM. No issues so far but does not get real cold here where I am.

 

[Volfy]

My diff was replaced. The new one is using the Genesis oil and started making noise. I'm starting to wonder if the oil needs *more* friction modifier? It's also colder here.. -15 to 0 celcius. Maybe the oil is too thick in this cold?? Something a friction modifier would help I think.

As I mentioned in your other thread, cold temp absolutely will affect how your gear oil behaves and, in turn, how your differential will function.

Let's look at the VI designation of 75w-85. It is written that way for a reason, with the "w" next to the first number (75), because that denotes the kinematic viscosity of the oil at low temp (40degC). The second number (85) denotes the kinematic viscosity of the oil at higher temp (100degC). Which is more important depends on the ambient temp range where you typically run your car. For me here in the warm south, where brutal Summer heat is much more of a concern, I prefer to run 75w-90 for better high-temp protection. If you live in the northern tundra, the lower number is likely more important to you. Even though both 75w-85 and 75w-90 have the same lower number, because of less viscosity modifiers added to the 75w-85, just as its viscosity will drop more when temp rises, it will also be less viscous (thick) when temp drops much below 40degC.

So what does this have to do with your LSD clutch plates chattering, you ask? Well, viscosity is basically the ratio between shear strain vs. shear stress. So, the more viscous a fluid is, the more force it will exert on the two bearing surfaces trying to shear the oil. This means a thicker oil will cause your LSD clutch plates to see higher "friction" and thus more likely to be active.

Pretty sure your Genesis service dept. uses 75w-85, as spec'ed. Does this means you should run an even lower-VI (thinner) gear oil? Not a good idea. That would compromise its protective properties at higher operating temps. Wanna talk about destroying your diff? That is a sure fire way to do it in a big hurry.

That is why an LS additive is a better remedy. Whatever OEM gear oil that's in your diff likely doesn't have enough of it... for the conditions you run your car in.

 

[Slip_Angle]

Please delete

 

[pulsar]

Ok, been following this for like to be proactive with my 2020 G70 3.3 sport. Don’t have noise or issues I’m aware of with my LSD and I’m not yet to the 36k miles, but am up on 3 years Of driving. Seems not everyone has had noise or chatter issues with our LSD. I’m also a fan of its not broke so don’t go monkey with something for no good reason and cause a problem. Based on all the reviews of different diff oils I’d be confused on what to even use for a change out Since some have had issues with the Genesis OEM diff oil. I’m at 17k miles, consensus to leave well enough alone until closer to 36k miles, or being past 3 years do a diff oil change here sometime?

 

[tompass]

I am of same mindset but decided to do mine at 36K and 4+ years of service. Reason given is that we have 10 year powertrain warranty and did not want any issues down the line if I did not do it and then had some related issue.

 

[Volfy]

Usually, following the OEM spec is a safe bet. Unfortunately, in this case, it is not. Or, to be more specific... the OEM spec is not sufficiently clear or precise enough.

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[tompass]

Usually, following the OEM spec is a safe bet. Unfortunately, in this case, it is not. Or, to be more specific... the OEM spec is not sufficiently clear or precise enough.

Perhaps but cheap enough for piece of mind.

 

[Volfy]

Perhaps but cheap enough for piece of mind.

By "OEM spec", I meant what is written in their own OM and SM for what should go into their own LSD.

 

[pulsar]

Usually, following the OEM spec is a safe bet. Unfortunately, in this case, it is not. Or, to be more specific... the OEM spec is not sufficiently clear or precise enough.

That’s what worries me. I like doing my own work and various fluid changes, but when OEM diff fluid may or may not cause a problem where I have none today, sort or creates a quagmire. Guess once I’m closer to 36k miles and I use Genesis or HMC diff fluid and a problem starts, my 10 yr 100k powertrain warranty should theoretically make corrections if required at that point.

 

[slimjim2525]

Reviving this thread, for a heads up. At 36,500 miles I changed my rear diff fluid in my 2021 G70 prestige with the LSD rear differential. I tried to get the OEM fluid but 3 places said they don't have it. I ended up putting Valvoline 75W90 with LSD additive in it. Immediately I noticed chattering coming from the rear end when cornering and the fluid was cold. This went away when the fluid got hot. I ended up putting CRC Trans X LSD oil additive. After adding this the chattering disappeared immediately. Not sure why the Valvoline with LSD friction modifiers wasn't good enough to prevent the chattering. On the next change will definitely being going to something else. Maybe Royal Purple, Redline, or Amsoil.

Reviving this thread again. Just changed my rear differential fluid again, now at 72k miles on the car. This time I used Amsoil severe gear 75W90. No chattering at all, super smooth. So clearly this product is better than the Valvoline I used the last time.

 

[Volfy]

If you don't want to have to add Trans-X, then for sure Amsoil is the way to go. Valvoline and Mobil1 LS just do not have enough FM for these Stinger/G70 LSDs. Not all LSDs require as much FM. My GMC Savana has GM's G80 Eaton LSD, and Valvoline works just fine as is, without adding FM.

 

[JCtx]

When an LSD makes noise only on tight turns, it has to be the fluid IMO. The noise alone means the clutch pack is working, or it wouldn't make any noise. Once the springs and/or clutch plates are worn out, it works as an open differential, and no noise, since there's no friction anymore. If something is out of whack inside, there would be other symptoms besides just noise in tight turns IMO. Now, if it's electronically controlled, the controller could be faulty, but doubt the entire differential had to be replaced. Curious what kind of LSD the G70s have: is it purely mechanical, or electronically controlled? Wish it was just a Torsen, which is a brilliant design, and purely mechanical, with no freaking clutches or electronic control. It weighs a little more than any clutch-type (electronic or not), but it's as reliable as an open differential. It's the only kind I'd like to own. Since the G70 doesn't have a Torsen, much prefer my open differential. And threads like this are proof I'm right. Ha ha. And yes, I'd try several fluids before replacing it, with just the tight-curve noise symptom.

 

[pulsar]

Good question above. I just looked at my window sticker and all it says is limited slip differential, so not exactly sure what type of LSD we actually have?

 

[Slip_Angle]

Genesis says "Limited Slip Differential (LSD) - mechanical multi-plate clutch-type"

 

[CVDH-TN]

I had my local shop perform the LSD oil change on my 2019 G70 3.3T RWD. They sourced the Kia oil recommended earlier in the thread. During the first couple of days after the change I noticed a faint chatter when taking sharp left turns but the sound went away after a couple of days.

 

[JCtx]

Genesis says "Limited Slip Differential (LSD) - mechanical multi-plate clutch-type"

And apparently it's the purely mechanical one, so no electronic actuation. An LSD can increase over-steer when applying power on turns, so the electronic type can be better in instances like that, where it reverts to open if needed. But if it's going to be a purely mechanical LSD, I'd much prefer a Torsen type, which never wears out, and it's as reliable as an open one. My 2.0T is much better off with an open one, since it doesn't have the power to need an LSD.