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ATF- Over full vs Under full AUTO TRANSMISSIONS IN GENERAL
What’s the less of the two evils, an auto trans that’s say 1/2 a qt too full or a .5 qt too low? I did a drain and fill on my truck and it doesn’t have a dip stick. The mfg says it’s full when it starts to drip when the fluid is at something like 30-40*c. Well I don’t have a scanner to monitor the temp. Short story I think I put too much in at first because it wasn’t up to temp yet. A lot ran out when I disconnected the hose I was pumping it in with. Too mud ran out that time so I had to add a little more and do the fill and wait for a drip procedure. I think I got it close to correct finally. At any rate if you had to error one way, would you rather be a little high or a little low?
I’d also like to ask, can one tell my the way it sounds and shifts if it’s too full? I know that they’ll howl or whine if they’re low, how about when they’re too full?
Last edited by Y2K_Frenzy; 02-04-2024 at 02:10 PM.
I am assuning a Corvette? In any case 1/2 quart over will be fine. The way would fill a corvette is run though gears, Place in reverse with harness unplugeed running of course and fill till starts coming out. . To low is a definate no no but and the vet has the snout on filter its pretty low so you would have to be really really low. Ideal fill is to even with the pan rail but that is impossible with a vet set up.
__________________ Frank formerly of Performabuilt, Now just me, What can I build for you today? Call or message me. Click sig pic for my facebook
I am assuning a Corvette? In any case 1/2 quart over will be fine. The way would fill a corvette is run though gears, Place in reverse with harness unplugeed running of course and fill till starts coming out. . To low is a definate no no but and the vet has the snout on filter its pretty low so you would have to be really really low. Ideal fill is to even with the pan rail but that is impossible with a vet set up.
No, not a Vette. It’s not a GM at all, but a Nissan Titan. I originally started this therad in “the lounge” since it was just a general question and not General Motors related at all but it was moved.
Just a little bit ago I heard it whining like a power steering pump so I let it warm up a little and then I took it for a drive so it could go through the gears and get up to temp before pulling the fill hole plug to see if any fluid would run out, and none did. So I added a little until it started slowing coming out of the fill hole. I guess it’s all good. We’ll see. If it’s over full I’m hoping worst case scenario is that there’s a vent it’ll be able to puke out of. I don’t know that there is one but hopefully so.
PS:
Maybe a Vette one day.
Last edited by Y2K_Frenzy; 02-04-2024 at 06:03 PM.
Both being too Low or too High causes issues that ate bad for the Transmission.
However being ONLY slightly Low or High is NOT Bad at all... and sometimes is actually a Good thing.
Oil Pan Design and Capacity, along with Filter/ Pick-Up Tube Design and Location, are all variables that will determine if the outcome will be Good or Bad.
So unfortunately there is NO simple answer here.
However, something that most people do not know...
Is that the Identification Markings on the Dip-Stick itself are often in the incorrect Locations.
This will provide an invalid Reading of the Fluid Level.
There are many Threads here discussing how to Inspect and if needed Correct the "Full-Mark" on the Dip-Stick.
Below is an Image of aligning the Dip-Stick to the Oil-Pan Rail/ Flange with a Quality "Machinist Straight-Edge"...
In order to establish and if needed Re-Mark the "Full-Mark" on the Dip-Stick.
Image shown below displays the Cold to Hot "Full-Range" Marking typically found on an ATF Dip-Stick:
Next is an Image withe a "Machinist Straight-Edge" across the Oil-Pan Rails to find the "Actual Full when HOT Mark":
Lastly, here is an Image where I made a New "Notch" into the side of the Dip-Stick that Indicated the New "Actual Full when HOT Mark":
Here is a Quote from one of my older Posted in another Thread that goes over this very Topic, should anyone wish to read a little more.
Originally Posted by vorteciroc
I might as well include the rest of the pertinent information.
First of all; very commonly the Transmission Dip-Stick incorrectly shows the "FULL mark" relative to the "actual FULL mark".
All Automatic-Transmission Dip-Sticks should have the "FULL mark" verified with the Oil-Pan removed.
As in the Image above...
Place a Straight-Edge across the Transmission Oil-Pan Rail.
Next create a mark on the Dip-Stick using a marker, where it is even with the Oil-Pan Rail.
Next remove the Dip-Stick, and measure 0.125" above the First mark.
Next make a Second mark at the 0.125" measurement.
The Second mark is going to represent the "new/ actual FULL mark".
I like to take a very small round File and create a notch in the Dip-Stick at the "new/ actual FULL mark".
The Image above shows a Dip-Stick with a notch added above the "original FULL mark".
The notch is the "new/ actual FULL mark".
Now that we have a proper "FULL mark" on the Dip-Stick...
The process of correctly reading the Dip-Stick is next.
First, as the other members have mentioned...
There must be a brief waiting period after adding ATF to the Automatic-Transmission Dip-Stick Tube.
After 10 minutes the ATF level may be checked.
The procedure for correctly reading the Dip-Stick is as follows...
Start the Engine and allow the Power-Train to come-up to operating temperature.
Place the Automatic-Transmission Gear-Selector in the Park position.
Allow the Engine to remain at an idle.
Now the ATF level may be inspected.... failure to follow this procedure, can result in inaccurate ATF level measurements.
The Image below shows a typical Dip-Stick:
The notch that was made into the Dip-Stick, now represents the "HOT FULL mark".
No, not a Vette. It’s not a GM at all, but a Nissan Titan. I originally started this therad in “the lounge” since it was just a general question and not General Motors related at all but it was moved.
Just a little bit ago I heard it whining like a power steering pump so I let it warm up a little and then I took it for a drive so it could go through the gears and get up to temp before pulling the fill hole plug to see if any fluid would run out, and none did. So I added a little until it started slowing coming out of the fill hole. I guess it’s all good. We’ll see. If it’s over full I’m hoping worst case scenario is that there’s a vent it’ll be able to puke out of. I don’t know that there is one but hopefully so.
PS:
Maybe a Vette one day.
Ah I assumed corvette because of the forum we are in , but sounds like you did it right.
__________________ Frank formerly of Performabuilt, Now just me, What can I build for you today? Call or message me. Click sig pic for my facebook
On these transmissions that do not have a dip stick. If you don't have a scanner fill the trans with the engine running until the fluid starts coming out of the fluid level plug. Then take it for a short drive and top off fluid if none comes out of the fluid level plug. Then take it for a long drive with a lot of stops and starts, trying to heat the trans up, (If the trans starts to feel funny take it easy driving back). Once you feel like you have gotten the trans up to temp come back and recheck fluid. If all is will drive for a week or so and check again. This should get the fluid level very close. These types of transmissions are a real pain in the behind to get the fluid level correct.
I highly recommending a Dip-Stick be added/ Installed in your Vehicle.
No one is going to regularly inspect the Fluid-Level when there are ONLY Level Inspection Plugs in the Transmission (and NO Dip-Stick).
If you have any desire to have a Vehicle actually last...
By this, I mean that this does not apply to the majority of new Vehicle Drivers, as they are Leased and then usually never driven again (Parted-Out or "Crunched").
Add a Ford "Shorty Style" Dip-Stick or Full-Size from the Aftermarket.
Then just make certain that the Full-Mark is "Accurate".
Both being too Low or too High causes issues that ate bad for the Transmission.
However being ONLY slightly Low or High is NOT Bad at all... and sometimes is actually a Good thing.
Oil Pan Design and Capacity, along with Filter/ Pick-Up Tube Design and Location, are all variables that will determine if the outcome will be Good or Bad.
So unfortunately there is NO simple answer here.
However, something that most people do not know...
Is that the Identification Markings on the Dip-Stick itself are often in the incorrect Locations.
This will provide an invalid Reading of the Fluid Level.
There are many Threads here discussing how to Inspect and if needed Correct the "Full-Mark" on the Dip-Stick.
Below is an Image of aligning the Dip-Stick to the Oil-Pan Rail/ Flange with a Quality "Machinist Straight-Edge"...
In order to establish and if needed Re-Mark the "Full-Mark" on the Dip-Stick.
Image shown below displays the Cold to Hot "Full-Range" Marking typically found on an ATF Dip-Stick:
Next is an Image withe a "Machinist Straight-Edge" across the Oil-Pan Rails to find the "Actual Full when HOT Mark":
Lastly, here is an Image where I made a New "Notch" into the side of the Dip-Stick that Indicated the New "Actual Full when HOT Mark":
Here is a Quote from one of my older Posted in another Thread that goes over this very Topic, should anyone wish to read a little more.
Reply with any Questions.
I read your original post and had this same question so will ask it here. Can you please clarify if your 2nd mark (0.125") is AWAY from the tip of the dipstick or TOWARDS the tip of the dipstick.
Thanks.
I read your original post and had this same question so will ask it here. Can you please clarify if your 2nd mark (0.125") is AWAY from the tip of the dipstick or TOWARDS the tip of the dipstick.
Thanks.
I believe the notch be made is towards the handle side.
That would be my guess also. I would rather not guess as to what his experience would recommend.
The full mark is always closer to the handle than the tip of the stick.
I haven’t looked real hard yet but I don’t know if there’s a mini dipstick that’ll fit my application but maybe.
Last edited by Y2K_Frenzy; 02-06-2024 at 12:02 PM.
The full mark is always closer to the handle than the tip of the stick.
I haven’t looked real hard yet but I don’t know if there’s a mini dipstick that’ll fit my application but maybe.
You mark the stick with a straight edge referencing the pan rail...just as shown in the photos
Then you scribe or notch the stick 1/8-1/4" ABOVE the pan rail...aka towards the handle.
You want the trans to be full of oil past the pan gasket surface when checked idling, warm, in park
Both being too Low or too High causes issues that ate bad for the Transmission.
However being ONLY slightly Low or High is NOT Bad at all... and sometimes is actually a Good thing.
Oil Pan Design and Capacity, along with Filter/ Pick-Up Tube Design and Location, are all variables that will determine if the outcome will be Good or Bad.
So unfortunately there is NO simple answer here.
However, something that most people do not know...
Is that the Identification Markings on the Dip-Stick itself are often in the incorrect Locations.
This will provide an invalid Reading of the Fluid Level.
There are many Threads here discussing how to Inspect and if needed Correct the "Full-Mark" on the Dip-Stick.
Below is an Image of aligning the Dip-Stick to the Oil-Pan Rail/ Flange with a Quality "Machinist Straight-Edge"...
In order to establish and if needed Re-Mark the "Full-Mark" on the Dip-Stick.
Image shown below displays the Cold to Hot "Full-Range" Marking typically found on an ATF Dip-Stick:
Next is an Image withe a "Machinist Straight-Edge" across the Oil-Pan Rails to find the "Actual Full when HOT Mark":
Lastly, here is an Image where I made a New "Notch" into the side of the Dip-Stick that Indicated the New "Actual Full when HOT Mark":
Here is a Quote from one of my older Posted in another Thread that goes over this very Topic, should anyone wish to read a little more.
Reply with any Questions.
1/2 quart over won't cause any problem. 1\2 quart under shouldn't either.
1/2 quart over won't cause any problem. 1\2 quart under shouldn't either.
I think it’s ok. It’s shifting normal. Except today though I think it was in a higher gear than it normally would’ve been in given the speed(under 40 mph). Like it didn’t down shift where it normally would have. I might be mistaken though. I’ll have to see what it does tomorrow I guess. I’m thinking about pulling the plug on the fill hole again after a drive to check it. I don’t think it’s going to be low, I’m expecting some fluid to come out, but I’m not sure if it’s going to be a drip or a gusher. I think we are hoping for a drip. When I topped it off last it was more if a slight run than a drip.
Out of curiosity, if a transmission is over full will it exhibit the same behaviors as one that’s low on fluid? Hard shifts, late shifts, etc? Or would it shift too soft if it’s too full?
Last edited by Y2K_Frenzy; 02-06-2024 at 07:37 PM.
I think it’s ok. It’s shifting normal. Except today though I think it was in a higher gear than it normally would’ve been in given the speed(under 40 mph). Like it didn’t down shift where it normally would have. I might be mistaken though. I’ll have to see what it does tomorrow I guess. I’m thinking about pulling the plug on the fill hole again after a drive to check it. I don’t think it’s going to be low, I’m expecting some fluid to come out, but I’m not sure if it’s going to be a drip or a gusher. I think we are hoping for a drip. When I topped it off last it was more if a slight run than a drip.
Out of curiosity, if a transmission is over full will it exhibit the same behaviors as one that’s low on fluid? Hard shifts, late shifts, etc? Or would it shift too soft if it’s too full?
Low fluid/high fluid doesn't cause any of that. If it's low enough what it will do is go into neutral when you stop and then slam back into gear. If it's over filled enough it will get up into the rotating mass of the gear train, churn up and create air bubbles and sometimes come out the overflow vent. Neither one is good.
02-04-2024, 11:55 AM
ATF- Over full vs Under full AUTO TRANSMISSIONS IN GENERAL 
