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How to Refill/Check Transmission Fluid

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194K views 21 replies 12 participants last post by  gherbert  
#1 · (Edited by Moderator)
Whether you drop the pan to replace the filter, accidentally open the bung as I did, or just want to check on the fluid and top off. Here's how to do it. It really is not hard at all, mainly because we have trucks, I did not use a jack at all.

These transmissions are used in lots of GM vehicles and quite a few BMWs as well. It is called a 6L50, it's used in both the V6 gas and L4 diesel versions of our trucks. There is no dipstick or any way to fill or check the fluid level from anywhere in the engine bay so don't waste your time looking for it.

Here we go, look at the pictures I have attached for reference

Filling:
Here's what you'll need, don't worry about the thermometer, the truck's instruments tell you the transmission fluid temperature. Also won't need the regular needle nose pliers, just the bent type.
The fluid needed is Dexron VI, it will come in many brands
Image


To fill, you have to find the little fill plug, it is on the passenger side (right side) of the transmission pan. (see picture)
Before you remove the fill plug, clean the area around it, I used to air in a can to spray away any dirt and dust around it. This is important because you do not want to contaminate the transmission fluid.

To remove the fill plug, use a pair of 90-degree bent needle nose pliers.
Find the top of the plug, it will first pop up, after this, you can wiggle the pin out with your hand:
Image

Image


I purchased a great little fluid pump from Home Depot for $10.00 and pumped in the fluid. (I originally bought 2, then did the run and drain procedure and nothing came out so I purchased another). I saw someone on a BMW forum make a siphon which was neat but using the pump very literally took less than 3 min to put all 3 quarts in with no mess at all.

Close the fill plug by reinserting the plug and pushing it down on the top of the plug to snap it back in.

Fluid Level Check/Drain Procedure:
You MUST do this to ensure the fluid level is correct, too much fluid is just as bad as too little fluid.
Get your truck level for this part, I drove my rear tires up on small flat bricks to level out because I did this in my garage and driveway which are slightly pitched.
There is a sticker on the transmission pan that explains the procedure:
Image

Here is EXACTLY what you do:
1. Turn the truck on and leave it on for the draining procedure.
2. Get to the transmission fluid temperature in your display so you can monitor it.
3. When the temperature is between 86-122 degrees F (30-50C) you will open the bung (#14 Socket). You don't need to rush here, it warms up slowly, I'd recommend waiting until it reads about 95 just to be safe.
4. Let the remaining fluid drain out.
IF no fluid comes out you need to turn off the truck and add more
5. When fluid is slowly dripping out, replace bung and torque to 18-foot lbs (108NM)
Image


And you're done!

It may seem counterintuitive here to drain the fluid to get the correct level but this is how it is done. In my case, I had to add 3 full quarts and about 1/4 came out when I did the draining so it took about 2.75 quarts.

Tips:
-Do they fill when your truck is cold because the exhaust pipe is right next to where you have to get the fill plug, your arm will definitely be touching it.
-Don't freak out if you accidentally opened the transmission fluid bung instead of the oil, the whole replacement took about 30 min. It takes longer to clean up.
-Don't drive the truck until you've filled and completed the fluid level check/drain procedure.

Here is a great video, literally the only one I could find of the process. The mechanic is great, he's changing a filter and replacing the fluid in a 6L50 in Australia. Note that he uses a thermometer which is why I got one ready but then realized we have a sensor.

This is another great video explaining exactly how the transmission pans and fills work. The pan in the Camaro in the video has the bung in a different spot but the concept and procedure are the same:

I hope this helps someone in the future!
 

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#2 · (Edited)
Nice contribution!
Strange how the 8speed M5T doesn't come with the helpful sticker.
Also, the checking temp for the 3.6 'Rados with 8spd should be in the 140's (131-149-hot)(video: 13:12).
I say should because the Camarros share the same trans and pan with the 'Rado. However, until I read it in a 'Rado service manual, it stays a "should be".
 
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#9 ·
Thanks for posting, looks the the MiniMax's exhaust is routed a little more friendly for doing a trans service. If I recall correctly the exhaust on my 15 Canyon with the 3.6 LFX is routed right under the transmission pan & it looks like it would cause some grief dropping the pan to change filter.

No transmission dipstick is one of my pet peeves about our trucks, a person can learn a lot about the condition of the tranny by a quick look/smell of the fluid on a dipstick.

I recall a few years back a member had installed an aftermarket Lokar trans dipstick, I thought about doing the same but I never did get around to installing one.
 
#10 · (Edited)
My 2016 Colorado V6 has a dipstick, your truck doesn’t?


A picture of the final mounting in the engine bay.

https://www.coloradofans.com/attachments/img_8479-jpg.288257/
386119
 
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#11 ·
Yes, I like having the dipstick to, works great..(y)
 
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#13 · (Edited)
Whether you drop the pan to replace the filter, accidentally open the bung like I did, or just want to check on the fluid and top off. Here's how to do it. It really is not hard at all, especially because we have trucks, I did not use a jack at all.

These transmissions are used in lots of GM vehicles and quite a few BMW's as well. It's is called a 6L50, it's used it both the V6 gas and L4 diesel versions of our trucks. There is no dip stick or any way to fill or check the fluid level from anywhere in the engine bay so don't waste your time looking for it.

Here we go, look at the pictures I have attached for reference

Filling:
Here's what you'll need, don't worry about the thermometer, the trucks instruments tell you the transmission fluid temperature. Also won't need the regular needle nose pliers, just the bent type.
The fluid needed is Dexron VI, it will come in many brands
Image


To fill, you have to find the little fill plug, it is on the passenger side (right side) of the transmission pan. (see picture)
Before you remove the fill plug, clean the area around it, I used air in a can to spray away any dirt and dust around it. This is important because you do not want to contaminate the transmission fluid.

To remove the fill plug, use a pair of 90 degree bent needle nose pliers.
Find the top of the plug, it will first pop up, after this you can wiggle the plug out with your hand:
Image

Image


I purchased a great little fluid pump from Home Depot for $10.00 and pumped in the fluid. (I originally bought 2, then did the run and drain procedure and nothing came out so I purchased another). I saw someone on a BMW forum make a siphon which was neat but using the pump very literally took less than 3 min to put all 3 quarts in with no mess at all.

Close the fill plug by reinserting the plug and pushing down on the top of the plug to snap it back in.

Fluid Level Check/Drain Procedure:
You MUST do this to ensure the fluid level is correct, too much fluid is just as bad as too little fluid.
Get your truck level for this part, I drove my rear tires up on small flat bricks to level out because I did this in my garage and driveway which are slightly pitched.
There is a sticker on the transmission pan that explains the procedure:
Image

Here is EXACTLY what you do:
1. Turn truck on and leave it on for the draining procedure.
2. Get to the transmission fluid temperature in your display so you can monitor it.
3. When temperature is between 86-122 degrees F (30-50C) you will open the bung (#14 Socket). You don't need to rush here, it warms up slowly, I'd recommend waiting until it reads about 95 just to be safe.
4. Let the remaining fluid drain out.
IF no fluid comes out you need to turn off the truck and add more
5. When fluid is slowly dripping out, replace bung and torque to 18 foot lbs (108NM)
Image


And you're done!

It may seem counter intuitive here to drain the fluid to get the correct level but this is how it is done. In my case, I had to add 3 full quarts and about 1/4 came out when I did the draining so it took about 2.75 quarts.

Tips:
-Do the fill when your truck is cold because the exhaust pipe is right next to where you have to get the fill plug, your arm will definitely be touching it.
-Don't freak out if you accidentally opened the transmission fluid bung instead of the oil, the whole replacement took about 30 min. It takes longer to clean up.
-Don't drive the truck until you've filled and completed the fluid level check/drain procedure.

Here is a great video, literally the only one I could find of the process. The mechanic is great, he's changing a filter and replacing the fluid in a 6L50 in Australia. Note that he uses a thermometer which is why I got one ready but then realized we have a sensor.

This is another great video explaining exactly how the transmission pans and fills work. The pan in the Camaro in the video has the bung in a different spot but the concept and procedure is the same:

Hope this helps someone in the future!
When you check the fluid level did you have to drive on wood and get the pan level. Or just park truck on level ground
 
#14 ·
Here's a crazy (obvious) idea! Why can't you just remove the filler drain plug and then stick something in as a dipstick? The trick would be determining the correct level, but you'd have that same issue with the aftermarket part. Determining it was low would probably be easier, since it would need to be probably at least 1/2 inch above the bottom of the check point bolt. And if nothing else a short substitute dipstick would allow you to at least check the condition of the fluid.

GM's idea of a check procedure that lets you know the fluid is low, but gives you no idea of how low, just seems absurd. It could very well be at the perfect level but not drain out and then you'd have to go to the time and expense of adding fluid, only do discover fluid immediately comes out.

If GM wanted to avoid the cost of a fluid dipstick tube, why not just make a fluid dipstick that could only be accessed under the truck? Such a device couldn't be that much more expensive than just the plug.
 
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#16 ·
Here are two examples of what I had in mind.

The first is perfect, except that it costs $100 and needs to be installed by dropping the pan.


This is cheaper, and looks like it has some flexibility on externally securing--there are other similar that only have one or two mounting points. But it is longer than what I had in mind.

 
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#22 ·
Since Discussion Starter is no longer Active
Last Post prior was: #20 · Sep 11, 2021
The Thread is great for reference.
But, will not yeild answers.
Thread being Closed.
Start a New Thread to Search for Any Answers
Duramini
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