Wow, this is amazing XR, I was literally just about to ask about this process.

 

Is this Abarth specific?

I don't think so. The non-abarth should have the same drain and fill plugs in the same location. I know for a fact the fill spec is the same.

Sent from my BBF100-2 using Tapatalk

 

Having already changed the diff (and fluid) in my Classica, I can verify there's no difference from what you have.

Edit: as a side note, I installed a complete "pumpkin" from an Abarth, and used Mopar 75W85 GL5 synthetic w/ LSD additive. It's been doing fine since early this spring with both race and street use. I'll examine the fluid closely this fall.

 

Great write-up. Thanks!
To clarify the diff fluid requirements, my understanding is that only the Abarth requires the LS additive while the Classica & Lusso use regular 75w-90 gear oil.

 

@XtremeRevolution

Slightly off topic, I know your car is a manual but would you happen to know what type of ATF I should use when changing out the auto trans fluid? The manual states the MOPAR brand but obviously I'd like to see if there is a more accessible/better off the shelf alternative.

Thanks.

 

I'm not sure about that to be honest with you. It looks like the fluid needs to meet JWS 3309 spec, which I don't think you'll find off the shelf. Our multi-vehicle OE and Signature Series ATFs meet that specification, if you're interested.

 

Sure, I'd be interested. I guess what I mean by off the shelf is anything on Amazon or I could buy online that's not OEM/dealership only.

It looks like Mobil 1 has a 3309 ATF also: https://amzn.to/2MaDBAb

Shoot me a PM with what you'd be interested in ordering and I can get you a quote shipped.

 

Are the replacement washers the same dimensions as the ones that go on the manual transmission fill and drain bolts? I still have a few of those kicking around.

 

I think so but don't quote me on that.

 

How to Change Gear Oil/Differential Fluid​

Overview:
This tutorial will walk you through the process of changing the gear oil/differential fluid on the 124 Spider.

A note regarding fluid selection:
According to Ameridian's blog, FCA recommends a 75W-90 GL-5 hypoid gear oil with FCA's multi-vehicle limited slip additive (for the Abarth). I called AMSOIL's technical team and they explained that our 75W-90 Severe Gear actually has limited slip friction modifiers already formulated in the gear oil, and that I don't need to add any extra. I already had some additive on hand, but decided not to use it. If you end up using something else, ensure that it already has limited slip friction modifiers formulated in the oil, or plan to purchase FCA's additive. If you have a Classica/Lusso, you don't have a limited slip differential, so you don't have to worry about the limited slip additive.

I used AMSOIL's Sever Gear 75W-90 because it has exceptional extreme pressure protection, it runs cooler than most fluids, is already formulated for limited slip differentials, and is now available (as of August 1st 2018) in a package that makes filling far easier than anything else on the market. You can find it here:

https://www.amsoil.com/shop/by-product/gear-lube/severe-gear-75w-90/?code=SVGPK-EA&zo=5224266

A note regarding service intervals:
I like to change gear oil often based on the ISO particle count oil analysis reports I've seen of gear oils and the effects silicon have on metallic wear. Silicon is a contaminant that enters the differential through the breather. This wear is typically out of range of a typical oil analysis report (5-15 microns) and will not show up on cheaper reports until it's too late. I like to change the fluid to get the abrasive silcon out before it causes wear.

Tools Required:
- 23mm and 24mm sockets and ratchet
- Shop towels
- Torque wrench
- Ramps/jack/jackstands
- Oil pan

Part Required:
- 1 Quart of 75W-90 Hypoid Gear Oil (see comment above). Actual fill spec is 0.63 quart/0.6 liter.
- Optional: Replacement washers for the drain/fill plugs (Available on Amazon.com), part number 995-41-400 according to a thread on Miata.net. I generally replace these every other service or if I see one is damaged.

Procedure:
1. Lift the car securely and as level as possible. The differential is on the back. Note the location of the drain (blue) and fill (red) plugs.

2. Remove the fill plug first, and remove the drain plug only if the fill plug has been removed.

3. Clean the metal shavings off of the drain plug magnet. Reinstall the drain plug and torque to ~40N-m (official spec is 40-53 N-m).

4. If you're using the AMSIOL Easy-Pack, remove the nozzle, peel back the seal, cut the tip off of the nozzle, and screw the nozzle back on.

5. Fill the differential until fluid starts coming out. Wait for the fluid to stop dripping, and thread the fill plug back on. Note, keep your oil pan underneath while you're filling. I made a video of this one to show how easy it is.
https://www.youtube.com/watch?v=SoG26Tj_SM4&t=

6. Re-tighten the fill plug and torque to ~40N-m (official spec is 40-53 N-m).

Here's what my factory differential oil looked like at ~4700 miles.

Xtreme, when you say you like to change the fluid often, how often is that? I am just at 2900 miles. I am not sure what all the issues with shifting and such. Best I can tell, Spidy shifts just fine, and any shifting issues are definitely operator induced

 

With regard to service intervals, I was talking about differentials alone. The issue here is the constant heating and cooling, while the breather is exposed to road dust on a regular basis, causing silicon contamination that is abrasive. This, combined with a low sump volume, causes wear over time. This isn't as much an issue for transmissions as it is for differentials, which are closer to the road and lower to the ground. I will most likely change my differential oil every 2 years with my driving. I drive around 3000 miles a year.

As for when to change the MTF, you'll start to notice shifting quality degrade over time, but generally I recommend every 30,000-45,000 miles. Changing it early won't hurt, and getting the break-in oil out early on the initial change will certainly help as well.

Keep in mind, as a bit of a perfectionist, I'll recommend people do what's best for their vehicles, not the minimum necessary.

 

Extreme
changed my MTransmission Oil today, with the pump it took 2 1/3 QUARTS. Mechanic asked me if there was a OIL gage for the trans, I told him mostly likely NO. Anyway when he drained it the bold had metal on it. Once finished screwed the draining bolt and started to fill from the above bolt till it started to overflow.

Is 2 1/3 quarts what's needed. tia

 

Yes that's approximately correct. The method you described is the way it should be done.

 

I tought I would get some metal chunks on the bolt, but were very fine. One last mode, waiting for the REMUS axleback, I told him to slack the exhaust bolt which he did and re=tightened them.

 

I did this and the MT fluid change tonight. This is a no-brainer and couldn't be simpler with the Amsoil pack with spout. Your shipping is ridiculously fast. I took 10 mile test drive and the rear end didn't seize up so I must have done it right.

 

I've recently learned that the recommended differential gear oil should be 75W-90 SG1, rather than 75W-90 GL5 that my previous research had revealed. That seems to be what you have used, if SG1 and Amsoil Severe Gear are synonymous. Do your data sheets explain the difference between the two?

Another question - the recommended ATF was JWS3309, but now seems to be JWS3324. Is there much of a difference? In identifying JWS3324 products, it appears that Dexron VI ATF products seem to be the equivalent.

 

Good question Dan. I switched rear diff fluid to the Amsoil Severe Gear Oil about 3,000 miles ago. The original advice was that Amsoil 75W-90 did not need a friction modifier but I'm wondering if that is correct. My last couple of times on my local track we ran the course clockwise which results in us turning in tight to a downhill chicane. The inside rear wheel gets unweighted as you turn into the chicane and start downhill and spins for at least 25 feet if you don't lift on the throttle some. I didn't pay any attention to it innitially but now I'm thinking the limited slip should actually shift the drive wheel to the outside wheel. Am I wrong in this thinking? If not, why didn't it do it? I'm not hearing any noises or experiencing any problems with the rear differential so I assume everything is as it should be.

 

I was directing the question at Andrei Pop (@XtremeRevolution), but thanks for helping to keep the discussion going @Chainringtatoo.

I notice in the Amsoil specs

AMSOIL Severe Gear is compatible with most limited-slip differentials. If limited-slip differential chatter occurs, add AMSOIL Slip Lock® friction modifier additive.

, which implies that the additive is not normally mixed in.

Mopar has changed the specs recently on a few items vs. the owner's manual, and I am in the process of verifying the information and incorporating it. Another thing they changed is Air Conditioning refrigerant, but I have a feeling that is an EPA thing. I feel obligated to get all the confusion cleared up, as people are depending on my Specs, since the owner's manual is so vague regarding fluid callouts.

 

These video gives you a bit more information on how LSDs behave as well. In this case, his outer wheel is on a snowbank and slipping substantially, and only after there is a significant speed differential between the passenger wheel and the driver wheel does the driver wheel start to pull away.

In this case, you can see the passenger wheel start to pull, while the driver wheel is spinning in place.

 

Thank you Andrei!! That is very helpful. I've determined that I am going to leave the GL-4 and GL-5 callouts in place, so that those purchasing alternative brand products are more likely to select the proper product.

 

I agree with Dan. Very helpful information. Like I said, I didn't give the wheel slip much thought until I was a having a discussion with someone else about that particular section on the track and how I was having difficulty getting back on the throttle there and they mentioned they thought my LSD would have done a better job there. Sounds like it did exactly as it was designed.

 

I was doing some testing with my car earlier and it exhibited similar performance to what I showed in the video above, but I didn't let it slip long enough to start catching since I didn't have the outer wheel completely off the ground (ah, that wonderful smell of tire smoke). With fluid being cold, it will take a bit longer for the LSD to engage as the clutches get closer together as the fluid thins (when it heats up). That's why you saw what you did in the video of the BMW on page 3; a ton of slip until the LSD heats up enough for the cones/clutches to start grabbing.

If you're looking for more aggressive LSD engagement, you might want to try a 75W-85 GL-5 gear oil, or just buy the upgrade available on GWR's site.

I was talking to Travis from Deyeme today about this. With both rear wheels off the ground, if you spin one, the other spins in the same direction. Great: the LSD works. If you put the transmission in drive (engine off of course), and spin one wheel, the other spins backward, but you feel quite a bit of resistance. I'd say a good 30-40 lb-ft of resistance. However, while aggressively driving the car, I never once had a "one wheel burnout." If I ever pushed the car hard enough, the entire back end would kick out.

I'll do some testing in the spring once the car is back out and the weather warms up a bit. Starting to get the impression that this LSD is not very aggressive at all.

 

I was doing some testing with my car earlier and it exhibited similar performance to what I showed in the video above, but I didn't let it slip long enough to start catching since I didn't have the outer wheel completely off the ground (ah, that wonderful smell of tire smoke). With fluid being cold, it will take a bit longer for the LSD to engage as the clutches get closer together as the fluid thins (when it heats up). That's why you saw what you did in the video of the BMW on page 3; a ton of slip until the LSD heats up enough for the cones/clutches to start grabbing.

If you're looking for more aggressive LSD engagement, you might want to try a 75W-85 GL-5 gear oil, or just buy the upgrade available on GWR's site.

I was talking to Travis from Deyeme today about this. With both rear wheels off the ground, if you spin one, the other spins in the same direction. Great: the LSD works. If you put the transmission in drive (engine off of course), and spin one wheel, the other spins backward, but you feel quite a bit of resistance. I'd say a good 30-40 lb-ft of resistance. However, while aggressively driving the car, I never once had a "one wheel burnout." If I ever pushed the car hard enough, the entire back end would kick out.

I'll do some testing in the spring once the car is back out and the weather warms up a bit. Starting to get the impression that this LSD is not very aggressive at all.

Getting ready to flush my diff oil tomorow. Happy to do a test if you know a good place to send it .
interesting thing is happening when the temperatures gets hot . When I am braking , heel toe shifting down into 3rd my rear end locks up and abs lamp blinks turning traction control back on. I’m thinking something is either wrong with my rear brakes , but considering it happens precisely when I downshift into 3rd could it be my diff ? Too much heat ? I am running wider stickier tires and putting down a lot more power . Any thoughts on this ? I’ll pull the oil Tomorrow and see what it looks like.

 

This video just happened to pop up at the top of one of my regular-visit websites... I thought it was fascinating.

 

Finally got around to changing my diff fluid this afternoon. The drain plug was a real * to get off - ended up having to use an impact driver to shift it. Lots of material on the plug so glad to get it out. Those Amsoil squirt packages are the business.

 

Hi Guys . Just drained my Diff . I got about 400 ml. ( should be 600 ml ) sorry dont know what that is in US quarts. Now I have refilled with 600 ml... *6 litre as per book. It has not filled to the top hole . Question .As per book or to the hole ?
S-Design just a Lusso with Abarth trim . Think it was only sold here in UK but may be wrong. But no different to any 124 underneath .
Side note ...gearbox was full to top .
Thanks
Pete D

 

Hi Guys . Just drained my Diff . I got about 400 ml. ( should be 600 ml ) sorry dont know what that is in US quarts. Now I have refilled with 600 ml... *6 litre as per book. It has not filled to the top hole . Question .As per book or to the hole ?
S-Design just a Lusso with Abarth trim . Think it was only sold here in UK but may be wrong. But no different to any 124 underneath .
Side note ...gearbox was full to top .
Thanks
Pete D

I don’t know the right answer to this, but I noticed the same thing when I changed mine. I opted to fill it until the oil came out of the diff fill hole.

 

FWIW, when I had my old NC Miata factory fill was usually low across forum users.......I thought I remembered seeing this same issue on the ND Miata forum?

[EDIT] Miata ND Forum thread on low diff fluid: Rear diff oil level from factory

The Fiat 124 factory manual just says fill to capacity listed as 0.63 Quarts / 0.6 Liters.

​

Surprisingly, the Miata ND factory manual is a little different and states fill to the brim of the fill plug hole.

.

 

How to Change Gear Oil/Differential Fluid​

Overview:
This tutorial will walk you through the process of changing the gear oil/differential fluid on the 124 Spider.

A note regarding fluid selection:
According to Ameridian's blog, FCA recommends a 75W-90 GL-5 hypoid gear oil with FCA's multi-vehicle limited slip additive (for the Abarth). I called AMSOIL's technical team and they explained that our 75W-90 Severe Gear actually has limited slip friction modifiers already formulated in the gear oil, and that I don't need to add any extra. I already had some additive on hand, but decided not to use it. If you end up using something else, ensure that it already has limited slip friction modifiers formulated in the oil, or plan to purchase FCA's additive. If you have a Classica/Lusso, you don't have a limited slip differential, so you don't have to worry about the limited slip additive. Use whichever fluid you feel comfortable with; this thread is intended only to provide instruction on how to change the fluid.

I used AMSOIL's Sever Gear 75W-90 because it has exceptional extreme pressure protection, it runs cooler than most fluids, is already formulated for limited slip differentials, and is now available (as of August 1st 2018) in a package that makes filling easier than anything else on the market. You can find it here:

SEVERE GEAR® 75W-90

A note regarding service intervals:
I like to change gear oil often based on the ISO particle count oil analysis reports I've seen of gear oils and the effects silicon have on metallic wear. Silicon is a contaminant that enters the differential through the breather. This wear is typically out of range of a typical oil analysis report (5-15 microns) and will not show up on cheaper reports until it's too late. I like to change the fluid to get the abrasive silcon out before it causes wear.

Tools Required:

• 23mm and 24mm sockets and ratchet
• Shop towels
• Torque wrench
• Ramps/jack/jackstands
• Oil pan

Part Required:

• 1 Quart of 75W-90 Hypoid Gear Oil (see comment above). Actual fill spec is 0.63 quart/0.6 liter.
• Optional: Replacement washers for the drain/fill plugs (Available on Amazon.com), part number 995-41-400 according to a thread on Miata.net. I generally replace these every other service or if I see one is damaged.

Procedure:
1. Lift the car securely and as level as possible. The differential is on the back. Note the location of the drain (blue) and fill (red) plugs.

2. Remove the fill plug first, and remove the drain plug only if the fill plug has been removed.

3. Clean the metal shavings off of the drain plug magnet. Reinstall the drain plug and torque to ~40N-m (official spec is 40-53 N-m).

4. If you're using the AMSIOL Easy-Pack, remove the nozzle, peel back the seal, cut the tip off of the nozzle, and screw the nozzle back on.

5. Fill the differential until fluid starts coming out. Wait for the fluid to stop dripping, and thread the fill plug back on. Note, keep your oil pan underneath while you're filling. I made a video of this one to show how easy it is.

6. Re-tighten the fill plug and torque to ~40N-m (official spec is 40-53 N-m).

Here's what my factory differential oil looked like at ~4700 miles.

Would you recommend adding a treatment to the manual gearbox if so witch one?

 

No, treatment or additive is not needed in the manual transmission.

Thanks,

Andrei

 

Hey question: Bought replacement washers for the drain fill plug on the LSD from the 124 forum post here but it turns out they don't fit my 124 spider! They are smaller than what was on my automatic 2017 124 Spider Abarth. I can't seem to find an alternative part out there, anyone know where I can buy the washers and if it's a different part number? This is what I bought: https://amzn.to/3aYlkRI
I notice the part number from the original post link is one number different. Link takes to part #
9956-41-400
but post lists it as: 995-41-400

 

Hey question: Bought replacement washers for the drain fill plug on the LSD from the 124 forum post here but it turns out they don't fit my 124 spider! They are smaller than what was on my automatic 2017 124 Spider Abarth. I can't seem to find an alternative part out there, anyone know where I can buy the washers and if it's a different part number? This is what I bought: https://amzn.to/3aYlkRI
I notice the part number from the original post link is one number different. Link takes to part #
9956-41-400
but post lists it as: 995-41-400

The MOPAR part number is 68314601AA for the diff washers. I just changed my gear oil.

 

I show - Filler and drain plug crush washers: 18mm ID / 25mm OD - Amazon.com: X AUTOHAUX 10pcs M18 Bronze Tone Car Engine Oil Drain Crush Flat Bonded Washer Gaskets: Automotive , (same as for the automatic trans.).

Perhaps you were using the wrong ones (that happened to work for the trans)? If this spec is wrong, I'll correct it, but it is believed to be correct.

 

Xtreme Revolution,

I wish I had better recall for my source(s) for both the open and limited slip differential Gear Lube specs. Steve just pointed out in another forum that the Service Manual seems to indicate the the friction modifier additive is already included in the gear lube. I'm quite certain it is not, and I think the note “Additive is contained within the specified gear oil for the rear differential” is a misinterpretation of the fact that the additive is to be added to the MOPAR # 68333589AA gear oil, not that it is already mixed in.

Also, I call out "MOPAR # 68333589AA, or a 75W-90 SG1 (GL-5) Hypoid Gear Oil equivalent", yet the Mopar catalog shows to be a 75W-85 API GL-4 Hypoid Gear Oil. I'm hoping you can help clear this mess up.

 

​

Limited slip differential oil

0.63 Quarts / 0.6 Liters

Mopar Long Life Limited Slip Additive for FIAT Spider* * Additive is contained within the specified gear oil for the rear differential.

directly out of the workshop manual.
Also redline and Amsoil do not require additional additives when used in the limited slip type differentials.