8 speed fluid change-level the truck or level the trans?

[ShadowsPapa]

Just follow the video.
It's really simple, no need to measure anything.
And for a feel good warm and fuzzy - check it again later after driving it a few miles.

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[Stan H]

Basically correct. I have done the latter of just running and holding them through the gears for a few seconds and the vehicle staying static.

This is the way , @ShadowsPapa Sent me the ZF version that is what I followed and 11k miles later running smooth

 

[Stan H]

I saw this and thought - yeah, it makes sense if it's 30 out he's going to have the inside temp set to 73 or so.
I mean - you see it set to 73, I had to assume you are using F temps. I figured it was cold out and you had the heat on set to 73.

At any rate, all three of mine have run over 165-170 transmission temps.
Maybe your cooler never bypasses so it's always cooling it.

This is a thing ,there was i say was a change in the bypass and heater on the side if the trans cases in 2022 I believe.
The trans I have now is a 2024 model and it runs cooler .

 

[g2020]

Just follow the video.
It's really simple, no need to measure anything.
And for a feel good warm and fuzzy - check it again later after driving it a few miles.

Thanks for the advice on watching the video.

Why attempt to marginalize the dude's advice in the video--passed on to us directly from a ZF guy who presented at an industry conference--when it explains why some have noticed the need to do a fluid level check the day after a pan drop? Hint: It's the thermostatic bypass valve, as explained in the video. Knowing why might be TMI for some people, but knowing that a final fluid level check is necessary, after driving the vehicle and allowing it to cool down, is not TMI. This is a critical part of the pan drop procedure.

 

[Maximus Gladius]

Thanks for the advice on watching the video.

Why attempt to marginalize the dude's advice in the video--passed on to us directly from a ZF guy who presented at an industry conference--when it explains why some have noticed the need to do a fluid level check the day after a pan drop? Hint: It's the thermostatic bypass valve, as explained in the video. Knowing why might be TMI for some people, but knowing that a final fluid level check is necessary, after driving the vehicle and allowing it to cool down, is not TMI. This is now an extension of the pan drop procedure.

The dude in the video is ‘partially correct’ suggesting to check the levels directly related to thermostatic bypass valve (TBV), but this, in my best speculative uneducated suggestion should only be done when and if the cooler is (for what ever reason) is flushed out, repaired or replaced and is emptied or oil volume in the cooler was altered from some repair. It doesn’t require this “extra check” if the cooler is full to begin with and depending on temp (I think it’s 75F) is when it opens to cycle through the cooler and transmission.

Once cooling cycles are done as TBV cools and closes, that system remains full until the next temperature spike, when it’ll open and oil will flow around again.

For anyone doing just a pan drop, the component is cold, the TBV is closed and will remain full and that level doesn’t change and it’s “fullness” doesn’t change the levels at transmission temp one settles on between 86-122F when fill plug is reinserted and at 86F, the TBV is open and flowing around anyway.

For this guy to assume we all need to check levels later because of the TBV issue would be the same thing if he felt we should recheck because the torque converter empties out when we do a pan drop and we all know that doesn’t happen.

So I think it’s all moot unless levels need to be rechecked because cooler was drained out for repairs.

 

[ShadowsPapa]

The dude in the video is ‘partially correct’ suggesting to check the levels directly related to thermostatic bypass valve (TBV), but this, in my best speculative uneducated suggestion should only be done when and if the cooler is (for what ever reason) is flushed out, repaired or replaced and is emptied or oil volume in the cooler was altered from some repair. It doesn’t require this “extra check” if the cooler is full to begin with and depending on temp (I think it’s 75F) is when it opens to cycle through the cooler and transmission.

Once cooling cycles are done as TBV cools and closes, that system remains full until the next temperature spike, when it’ll open and oil will flow around again.

For anyone doing just a pan drop, the component is cold, the TBV is closed and will remain full and that level doesn’t change and it’s “fullness” doesn’t change the levels at transmission temp one settles on between 86-122F when fill plug is reinserted and at 86F, the TBV is open and flowing around anyway.

For this guy to assume we all need to check levels later because of the TBV issue would be the same thing if he felt we should recheck because the torque converter empties out when we do a pan drop and we all know that doesn’t happen.

So I think it’s all moot unless levels need to be rechecked because cooler was drained out for repairs.

Possibly true, but how much drains out of the lines with the engine not running to keep them full. Me, worth the recheck

 

[Maximus Gladius]

Possibly true, but how much drains out of the lines with the engine not running to keep them full. Me, worth the recheck

From my one year to the next, and checking once in between, there was no difference

 

[AmosMoses]

To answer the question about if I measured what I took out. I did but didnt go by that, more just to make sure I was in that window of refill. The fill method negates putting in what you take out. My refill amounts are around 5.5 quarts as other people report though.

Also, what are we saying is normal operating temps? I say 180-190 depending on ambient air temps. That is roughly the midway point on the dash gage at 12 o'clock. What is excessive though? I noticed my temps at 205-210 when wheeling a month or so ago. Iam not sure if 4 low helped or hurt. I did notice a little erratic shifting going up hill in 4 low but it was my first time using 4 low for an extended period and was suggested when offroading to lesson the load on the transmission. Ive been monitoring trans temp ever since changing my fluid at 50k and its not often that I go over 190, especially since temperatures are falling.

 

[ShadowsPapa]

Also, what are we saying is normal operating temps? I say 180-190 depending on ambient air temps. That is roughly the midway point on the dash gage at 12 o'clock. What is excessive though? I noticed my temps at 205-210 when wheeling a month or so ago. Iam not sure if 4 low helped or hurt. I did notice a little erratic shifting going up hill in 4 low but it was my first time using 4 low for an extended period and was suggested when offroading to lesson the load on the transmission. Ive been monitoring trans temp ever since changing my fluid at 50k and its not often that I go over 190, especially since temperatures are falling.

That's not hot at all.

Mine ran a high of 185 today with 37 degree outside temps, running 67 mph on our hills.

Over 25 miles it spent about 60% of the time in 7th, 38% in 8th and the rest it was in 5th to take the hills. So I saw a lot of 2400 RPM time on the highway between here and Pella.

The transmission temps ranged from 165 to 185. It was 185 in the hills and after a good deal of driving - so it took a while to get there.
That's unloaded, not towing, little wind, quite a few hills and temps in the 30s.

 

[Maximus Gladius]

180-190 seems pretty normal range for most here. 210 is up there. If I saw that, I’d probably have a cow.

If you’re wheeling as often as you can and you’re seeing this, I’d be doing more frequent pan drops.

 

[ShadowsPapa]

180-190 seems pretty normal range for most here. 210 is up there. If I saw that, I’d probably have a cow.

If you’re wheeling as often as you can and you’re seeing this, I’d be doing more frequent pan drops.

LOL - 210 is nothing, either. Modern fluids handle that with ease.
We hit 195 to a bit over 200 driving on the interstate from CO to IA on a 90 degree day.
Below is an example - long trip, 70-75 mph, reasonably flat, transmission not hunting.

I hit 210 towing on a 90 degree day.

It's nothing these days.

Why do people freak out over such temperatures? Did you know that some companies state their fluid will handle 300 degrees without trouble?

 

[Maximus Gladius]

Why do people freak out over such temperatures? Did you know that some companies state their fluid will handle 300 degrees without trouble?

Nobody is freaking out, just being smart as to what to do when temps get “hot” and ZF says it’s being prudent to change the oil. They don’t state what temp they say creeps into the “hot” range so it’s only being prudent that 210 would be in the vicinity of “hot”.

Other companies claim their oil can go 300F, that’s awesome for them but I’ve not read what ZF says is hot and we may not be using that oil. I’m thinking the 8/9 ATF is semi-syn so, part synthetic, part not. Maybe the part that isn’t can’t handle the hot temps so we’ll see the effects of oxidation sooner than a full syn.

I’d like to see what happens when this transmission is pushed to 300F.

 

[ShadowsPapa]

Nobody is freaking out, just being smart as to what to do when temps get “hot” and ZF says it’s being prudent to change the oil. They don’t state what temp they say creeps into the “hot” range so it’s only being prudent that 210 would be in the vicinity of “hot”.

Other companies claim their oil can go 300F, that’s awesome for them but I’ve not read what ZF says is hot and we may not be using that oil. I’m thinking the 8/9 ATF is semi-syn so, part synthetic, part not. Maybe the part that isn’t can’t handle the hot temps so we’ll see the effects of oxidation sooner than a full syn.

I’d like to see what happens when this transmission is pushed to 300F.

210 isn't hot - and frankly, hasn't been.

I don't know where the "being prudent" comes from as it's a safe temp.

Here's from the web -

Operating temperatures between 175 degree F and 220 degree F are considered normal.

This keeps coming up and no, 210 is not hot and it's not a danger area by any means.
210 is no reason to start thinking about fluid changes. That's such old thinking.

You'll find a lot of talk about 200 being too hot, 210 being too hot - that's old old old thinking and even then, wasn't true. Older transmissions ran their fluid through the RADIATOR to cool the fluid - so you'd have fluid hitting temps in the 210-220 range very frequently. If old ATF could handle it, then the new stull will do even better.

I've found people with Ford and GM transmissions talking about towing at trans temps of 230 and they don't bat an eye.

210 is nothing at all.

 

[Vtur]

I've seen mine up to 220f while climbing up some switchbacks. Normal driving is 190-200 on mine.

 

[AmosMoses]

I think shadowpapa is right on transmission temps. 200 is the mean on the digital gage.

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