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How to Change Manual Transmission Fluid

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How to Change Manual Transmission Fluid​

Overview:
This tutorial will walk you through the process of changing manual transmission fluid on your Fiat 124 Spider. According to FIAT, this is a long life fluid with no service interval listed, but I didn't like that my transmission would occasionally get notchy. After missing 3rd gear twice due to that inconsistency (especially when hot), I decided to try something different, and I was dying to try out our 75W-90 GL-4 MTF in this car. My car had 1,450 miles when I drained the transmission fluid for this tutorial.

Tools Required:
- 24mm or 15/16" wrench (I was unable to fit a 24mm socket between the transmission and the subframe to remove the fill plug)
- Shop towels
- 12mm socket and ratchet
- Ramps/jack/jackstands
- Oil pan
- Optional: ft-lb Torque Wrench.

Part Required:
- 3 Quarts of Synthetic 75W-90 GL-4 or your favorite manual transmission fluid.
- A fluid pump

Fluid Options:
I've personally used AMSOIL 75W-90 GL-4 MTF and AMSOIL Synchromesh and had great experiences with both in the past. In the 124 Spider, I'm using the 75W-90 GL-4 MTF. At the time of this edit, I've been using the fluid for two years and am pleased with its performance.

The 75W-90 GL-4 can be a bit stiff on cold mornings below ~40F in freezing temperatures for the first mile or two, but works well in hot conditions and with severe driving. The Synchromesh fluids can be a bit more notchy when very hot but will shift better on colder mornings than the 75W-90 will, at least until the transmission warms up a bit, and will be better suited for normal driving conditions. However, Synchromesh fluids mighit have lower EP additive concentrations and as a result, may not be well suited for exceptionally severe driving, frequent racing, and modified cars where hard launching and shock loading are the norm. I personally use the 75W-90 since I only drive the vehicle in warmer weather and it stays in the garage over winter.

Some people have also reported good experiences with the Ford XT-MS-Q5 fluid, which seems to work well but is a tad more expensive. Other synchromesh fluids may work as well. Choose the fluid that's best suited for your driving conditions. Note that this same transmission in the NC Miata used a 75W-90 GL-4 MTF, so that's what I'd recommend sticking to.

Notes:
- For ease of filling, I used the AMSOIL Bottle Hand Pump, which screws onto the quart and gallon bottles. This made filling the transmission a breeze.
- FCA does not list a service interval for this fluid, but I don't like keeping break-in fluid in gear boxes for very long. A picture further down explains why.
- There are crush washers on both the drain and fill plug. You may change these if you want to, but I did not feel it necessary to do so. If you want to change them, pick some up at your dealer prior to starting this service. I typically change them every other service interval if they look damaged.

Procedure:
1. Lift the car securely. If you can only lift one side of the car, lift the front, as the drain plug is toward the rear of the transmission.

2. Once underneath the car, use a 12mm socket to remove the 4 bolts holding the cross brace on.


3. The fill plug and the drain plug are shown here, facing the driver's side of the car. Make sure you can remove the fill plug before you remove the drain plug.


4. Using a 24mm or 15/16" wrench, first remove the fill plug, then the drain plug.


5. For the first transmission fluid change, you'll find a substantial amount of metal shavings stuck to the magnet on the drain plug. This is normal, do not be alarmed. This is all break-in metal. Simply wipe it off on a towel.



6. The oil will most likely have metallic swirls. Note that this is also break-in metal, do not be alarmed unless you find chunks of metal (I found none).


Obligatory AMSOIL promo shot


7. Reinstall the drain plug and torque to ~29-42 ft-lb.

8. Fill the transmission to 2.2 quarts (2 quarts + 6.4oz). If using the AMSOIL bottles and fluid pump, the AMSOIL bottles are marked on the side with a bar visible to show remaining fluid. Fill the full two quarts until empty, then pump the 3rd bottle until the level shows 20 ounces still remaining in the bottle. I know what you're thinking here...if the trans holds 2 quarts and 6.4oz, why is he filling 2 quarts and 12oz? The reason is simple: there are a few ounces of oil still left in the pump and the hose. Alternately, you can just keep filling until fluid starts to trickle out of the fill hole, which should bring you to about the same point.


9. All in all, you should have filled 2 full quarts and ~6.5oz. If you pour the remaining oil from the two empty bottles, and empty the pump into the 3rd bottle, you should have ~25.5 ounces (or just over the 24oz mark), validating that the transmission was filled to the correct capacity.


10. Reinstall the fill plug and torque to ~19-28 ft-lb.

11. Reinstall the cross brace and torque bolts to ~22 ft-lb.

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Thanks XR - really appreciate your tutorials on here.
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Thanks XR.
I did a fluid change on my NC miata tranny with good results and was contemplating doing it on my Abarth. You have inspired me to crawl under my car again this weekend.
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Great tutorial. Looks like a very easy project. I needed a project tomorrow before a go on a long drive on Sunday. Do you have any plans on changing the fluid in the rear. I would like to have all fluids changed to Amsoil. Been using their oils for years with great results. Motor was done at 1000 and now the trans at 2000. Thanks again.
Great tutorial. Looks like a very easy project. I needed a project tomorrow before a go on a long drive on Sunday. Do you have any plans on changing the fluid in the rear. I would like to have all fluids changed to Amsoil. Been using their oils for years with great results. Motor was done at 1000 and now the trans at 2000. Thanks again.
No plans on changing the fluid in the rear until I figure out exactly what it is. As far as I can tell, it is a 75W-90 GL-5 gear oil with friction modifiers specific for the type of LSD used in the Abarth. Because LSD performance can be altered with the use of different fluids that have different friction properties, I'll be doing more research on that one before I touch it. It may just require a slip-lock additive to a standard gear oil like many limited slip differentials do, but I'm not ready to test that yet.
A bit of a review on the AMSOIL fluid, the first drive was precisely what I expected; I was not disappointed. In my last car, using this transmission fluid totally eliminated the notchy shifting. I was hoping it would do the same, since my 124 Spider's transmission was occasionally notchy, especially when hot. I was warned of this when I bought the car from another NC Miata owner on the other forum I administrate.

I'm happy to report that this fluid totally eliminated the notchy shifting. It significantly smoothed out shifts without making them feel dull. I still get the mechanical feel of the transmission without the inconsistency and "notchyness" I felt previously. This will do perfectly well.

I wanted to wait to use this in my car to make sure it performed well before advertising it on this forum, and having felt the shifting yesterday, I can recommend it with complete confidence. If anyone else wants to give this a shot, just send me a PM and I'll get you a package pricing on the fluid and pump.
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Nice job, XR! Thanks for your time and effort to post this tutorial.

#1, Looking at the photos, I'm guessing it will be difficult at best to get the new juice in the tranny without a pump, correct? I like the idea of that pump, I didn't know such a tool existed.

#2, You know I've got my overbuilt wood ramps for getting under the car. The drain bolt appears to be on the driver's side. If I were to get the passenger wheels up on another layed-flat piece of 2x lumber (elevating the right side anorher 1.5"), do you think it would drain out any more old fluid?

Watch for PM.

Thanks,
Steve.
Nice job, XR! Thanks for your time and effort to post this tutorial.

#1, Looking at the photos, I'm guessing it will be difficult at best to get the new juice in the tranny without a pump, correct? I like the idea of that pump, I didn't know such a tool existed.

#2, You know I've got my overbuilt wood ramps for getting under the car. The drain bolt appears to be on the driver's side. If I were to get the passenger wheels up on another layed-flat piece of 2x lumber (elevating the right side anorher 1.5"), do you think it would drain out any more old fluid?

Watch for PM.

Thanks,
Steve.
You need a pump of some kind, or the fluid is not getting in there. Another method I've seen people use is get one of those big black suction pumps you can find at most hardware stores and use that method, but cross-contamination with whatever was in there before becomes a concern, plus they tend to leak and make a mess. That pump really makes filling longitudinal transmissions and differentials a breeze.

I don't think you'll get any additional fluid out by raising the passenger side a little more. The drain plug goes into a little pocket of the transmission that is lower down than the rest of the sump. On perfectly level ground, or with the vehicle on an incline, you'll get out almost all of the fluid.

As a bit of an update, I've discovered that reverse gear, which is usually stiff on cold starts, is notably easier to engage since I changed the fluid.
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My review of a Amsoil trans refill

My review of changing the trans fluid to Amsoil 75W90. This is my opinion and my opinion only.
First thing I noticed when removing the fill plug was a slight leakage of fluid. This is what I expected as most fill opening are filled until they drip ever so slightly. Not to go by this along, I measured the stated amount of fluid as stated by XR and added one more oz. I have the pleasure of having a fluid pump that will pump one Qt. plus and is marked in oz. all the way to 45 oz. In two pumps I added the stated amount and began to add the extra and got no further than 1/2 oz more before it began to drip out. That's works for me. Installed the plug and cleaned up the slight overspill.
Now for a review on what the Amsoil did for my car. I drove a total of 225 miles today. The first thing I noticed after warm up and about fifty miles under my belt.
1. The trans goes into reverse gear so much easier. Before I needed to give it a little effort.
2. First gear is engaged with very little effort.
3. Second to third engages with out the double clutch as before. This was one of the issues that I was not very happy about with my car.
4. Most of my complaints were with the lower gears. This issue has been resolved for a simple $40.00
investment and 45 minutes of my time. Today was one of the best drives I've taken. If anyone in the Nj/ Ny area is familiar with Bear Mountain State park, it was a beautiful day filled with motorcycles,
Corvettes and my Abarth.
Thanks to XR for printing an extensive "How To"
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No plans on changing the fluid in the rear until I figure out exactly what it is. As far as I can tell, it is a 75W-90 GL-5 gear oil with friction modifiers specific for the type of LSD used in the Abarth. Because LSD performance can be altered with the use of different fluids that have different friction properties, I'll be doing more research on that one before I touch it. It may just require a slip-lock additive to a standard gear oil like many limited slip differentials do, but I'm not ready to test that yet.
I don't want to hijack this tutorial thread, but everything I come across for the standard (not the LSD) rear diff. states "hypoid gear oil SG1" which the interwebs come back with as Mazda's rear diff. oil, but states no viscosity ratings. Actually, I don't think it was stating a difference between the LSD and the standard differential, not at AmeriDan's blog anyway, but his blog states 75W/90 GL5 (without explanation of the origin of that rating). One of my local Fiat parts desks wants $39/qt for the trans. oil, and $50/qt for the rear diff!! They're drunk! This was not the dealer I bought the car from.

I just called a local Mazda shop, asking about rear diff. oil for a 2016 Mazda MX5, and he stated "Rear Differential Hypoid Gear Oil SG1, $37.44/qt". He said the bottle was not marked for viscosity or GL/4 or /05. Huh.

Steve.
I don't want to hijack this tutorial thread, but everything I come across for the standard (not the LSD) rear diff. states "hypoid gear oil SG1" which the interwebs come back with as Mazda's rear diff. oil, but states no viscosity ratings. Actually, I don't think it was stating a difference between the LSD and the standard differential, not at AmeriDan's blog anyway, but his blog states 75W/90 GL5 (without explanation of the origin of that rating). One of my local Fiat parts desks wants $39/qt for the trans. oil, and $50/qt for the rear diff!! They're drunk! This was not the dealer I bought the car from.

I just called a local Mazda shop, asking about rear diff. oil for a 2016 Mazda MX5, and he stated "Rear Differential Hypoid Gear Oil SG1, $37.44/qt". He said the bottle was not marked for viscosity or GL/4 or /05. Huh.

Steve.
Rear differentials would most likely be GL-5. GL ratings are used to differentiate EP (extreme pressure) additive levels. Because the decomposition of extreme pressure additives under heat can cause accelerated soft metal wear (re: synchros), manual transmissions typically use lower concentrations. GL-3 typically has 3% EP additives, GL-4 has 4% EP additives, and GL-5 oils have 6.5% EP additives. Higher concentrations are used in rear differentials as there is no concern with soft metal wear. For conventional open differentials, a 75W-90 GL-5 gear oil is perfectly suitable. Mazda may be using a lower viscosity GL-5 gear oil for fuel efficiency purposes, but this isn't likely to be anything special. For the non-Abarth rear end, a synthetic GL-5 75W-90 gear oil will be perfectly suitable. AMSOIL's costs a lot less than $37.44 a quart.
i seriously can't wait to change the oil in my car.

currently at 600 miles...probably change both (engine and trans oil at 1200 miles) especially after seeing the metal flakes on the magnetic plug. I shutter every time I see/think of that!!!

mahalo for the suggestions and the thread!!!
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...probably change both (engine and trans oil at 1200 miles) especially after seeing the metal flakes on the magnetic plug. I shutter every time I see/think of that!!!
I know, right?? Couldn't believe how much crud was on the plug.

Jobs for this weekend:

1. Resurrect the turbo
2. Change engine and transmission oil

Speaking of which, anyone got a recommendation for a trolley jack that works well with the Spider? It appears my last jack disappeared with my torque spanner when we moved house 2 years ago.
...
Speaking of which, anyone got a recommendation for a trolley jack that works well with the Spider? ...
I use a Harbor Freight one. With lowered springs it's still not enough to clear the front lip and reach the front sub frame crossmember for lifting, so run the front of the car up a 3" 'ramp'. Goes to the rear sub frame no problem. If I recall it was about $100 for a 3 ton low profile jack (it's very heavy!).

Also use hockey pucks on axle stands at the seam lift points to support the car.
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According to the FSM:
Rear differential oil: 0.63 Quarts / 0.6 Liters: MOPAR Long Life Hypoid Gear Oil for FIAT Spider
p/n 68333589AA

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.

The same p/n is listed for both (...589AA)

I see 75/90 being thrown around a lot on the ND forums as far as viscocity, but I haven't seen anything official from MoPar saying what it is.
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According to the FSM:
Rear differential oil: 0.63 Quarts / 0.6 Liters: MOPAR Long Life Hypoid Gear Oil for FIAT Spider
p/n 68333589AA

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.

The same p/n is listed for both (...589AA)

I see 75/90 being thrown around a lot on the ND forums as far as viscocity, but I haven't seen anything official from MoPar saying what it is.
Viscosity might be assumed as being a 75W-90 based on previous models. They might go thinner for fuel efficiency, in which case going thicker won't harm but a tiny fraction of a mile per gallon, but they won't go thicker and don't need to.

Thanks for doing the research on this one. So it seems that they use the same fluid in both from Mazda, and that the fluid has the LSD additive required in both cases, even though it isn't needed for the non-LSD transmission. Am I correct on this analysis?
...that the fluid has the LSD additive required in both cases, even though it isn't needed for the non-LSD transmission. Am I correct on this analysis?
Looks that way. The table had the same p/n for both descriptions beside the standard and LSD diffs, even though they were both specified individually. Looks like draining the diff is part of its removal, so that appears to be the only "official" reason for needing to fill it up again, ever (lol). And on the 75W90, you're probably right. I don't think you'd go heavier (80/90, 75/140) in a small car application, and there isn't much available that's lighter, at least commercially in the US, in a GL-5, like 75/80 or 75/85.
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I just finished the manual transmission oil change, full of Amsoil now. Using the Amsoil pump was a good idea, although honestly, I wish my car would have been higher off the ground. My drive-on ramp system (all 4 wheels 7 inches above the ground, ramps are 10 feet long, car level to the ground) worked great but any lower and I would not have been able to shimmy all the way to the tranny, which is about dead center under the car. Having it higher would have allowed an easier time with the pump system, too. Now, if I used jack stands rather than full length ramps, I could have made access from the side of the car rather than the front or rear end. I went under from the front. Lesson learned.

Anyway, my tech question/comment. I pumped in fresh gear oil from the third bottle until I got a steady trickle of oil leaking out of the fill hole, leaking slowly for several more seconds after removing the pump tube and inserting the fill plug. From the first 2 bottles I pumped until nothing but air came out. Following XR's tutorial, afterward I drained the pump and the two empty bottles into the third, nearly full bottle. That third bottle now shows dead-on at 28 ounces in the bottle, 4 ounces under the quart mark. And I bet a better part of an ounce trickled out of the fill hole. This being the case, 2.2 quarts are not in the tranny. 2+ are, though. A.K.A. 2 liters

My theory- the transmission needs 2 quarts (or rather 2 liters) for proper operation. 2.2 quarts is an arbitrary amount to get oil high enough to spill out of the fill hole, assuring the mechanic that he's fully filled the transmission. Agreed?

Who would worry about being 2-3 ounces under 2.2 quarts? (2.2 quarts equals 2.08 liters.)

I bet if I had the front wheels only up on ramps, or the front of the car on jack stands, I could have put in 2.2 quarts due to the tranny fill hole being marginally higher than mine was sitting level to the ground.

Steve.
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I just finished the manual transmission oil change, full of Amsoil now. Using the Amsoil pump was a good idea, although honestly, I wish my car would have been higher off the ground. My drive-on ramp system (all 4 wheels 7 inches above the ground, ramps are 10 feet long, car level to the ground) worked great but any lower and I would not have been able to shimmy all the way to the tranny, which is about dead center under the car. Having it higher would have allowed an easier time with the pump system, too. Now, if I used jack stands rather than full length ramps, I could have made access from the side of the car rather than the front or rear end. I went under from the front. Lesson learned.

Anyway, my tech question/comment. I pumped in fresh gear oil from the third bottle until I got a steady trickle of oil leaking out of the fill hole, leaking slowly for several more seconds after removing the pump tube and inserting the fill plug. From the first 2 bottles I pumped until nothing but air came out. Following XR's tutorial, afterward I drained the pump and the two empty bottles into the third, nearly full bottle. That third bottle now shows dead-on at 28 ounces in the bottle, 4 ounces under the quart mark. And I bet a better part of an ounce trickled out of the fill hole. This being the case, 2.2 quarts are not in the tranny. 2+ are, though. A.K.A. 2 liters

My theory- the transmission needs 2 quarts (or rather 2 liters) for proper operation. 2.2 quarts is an arbitrary amount to get oil high enough to spill out of the fill hole, assuring the mechanic that he's fully filled the transmission. Agreed?

Who would worry about being 2-3 ounces under 2.2 quarts? (2.2 quarts equals 2.08 liters.)

I bet if I had the front wheels only up on ramps, or the front of the car on jack stands, I could have put in 2.2 quarts due to the tranny fill hole being marginally higher than mine was sitting level to the ground.

Steve.
I do believe that 2.2 quarts is more of an arbitrary amount since the fill plug is also the level plug. In addition, there may be areas in the transmission already holding oil, so to reach the 2.2 quart capacity, you may need less than 2.2 quarts. Also, I agree that how level your car is when performing this service may also affect how much fluid goes in. Manual transmissions are fairly simple; they are lubricated through direct contact as opposed to a pump, so as long as you're generally in the ballpark, you won't see any negative effects.

I had my front wheels up on ramps, so the car had a bit of an incline.

How does the shifting feel?
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Thanks, I'm not going to worry about a couple sips of oil then.

I took an obligatory ride around the block, just to move the oil around, but it was about to rain so I didn't go for a longer drive yet. I'll give an update soon.

What is a good method to clean the pump?

Steve.
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