8-Speed Automatic 850RE Transmission Question?

J.Ralston

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Hello everyone. My 2021 JL Jeep Wrangler Unlimited Rubicon is the very first Jeep that I have ever owned and so far I am loving it. When I ordered my Jeep, I ordered it with the 3.6 liter V-6 with eTorque and the 8-Speed Automatic 850RE Transmission. After the engine, transmission, transfer case and front and rear differentials all get a chance to break in, I plan on putting Amsoil synthetics in everything.

I will do my engines motor oil changes at about every 2,500 to 3,000 miles but when my Jeep gets to around 10,000 miles to 15,000 miles put on it, I will then go and put Amsoil in the front and rear differentials, transfer case and automatic transmission.

I was curious if anyone else in here has done the same exact thing? I know that at every automatic transmission fluid change on these transmissions that the filter is integrated into the pan so I was curious if the entire fluid from the transmission, including inside the torque converter, if everything drains back into the pan when the vehicle is not running? I also know that the transfer case also takes automatic transmission fluid too. But I’m assuming that the transfer case is a totally separate system from the transmission. Or in other words, it takes its own fluid and does not share fluid from the automatic transmission right?

Any help and advice would be very much appreciated!
Thanks.
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viper88

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The ZF does not share fluid with transfer case. Totally different components. Torque converters always hold some fluid. I would leave the ZF alone until service is actually required. I would only let someone who knows the ZF service it. I would also only use what ZF specifies.
 

Rogue Toad

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I hesitate to comment in any "oil threads" on a forum, but nonetheless... As a former engine design engineer I have to make the side comment that doing oil changes every 2,500-3,000 miles is 100% unnecessary unless you are sitting idle in a dust storm all day. That is "grandpa" advice at this point, and hasn't been relevant since the 80's. (Though doing a short interval on your very first change is still a good idea.)

With modern synthetics you are perfectly fine at 10K miles in "normal" everyday driving conditions, or 5,000-7,500 if doing a lot of off-roading, towing, etc. So even under the most "safe" strategy there is no purpose to more frequent oil changes.

I've seen literally dozens of engines torn down from fleet vehicles, dyno durability tests, etc. and using synthetic oil the main bearings, for example, showed nearly no sign of wear using the above guidelines.

Let the "but oil is cheap insurance" comments begin...
 
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calemasters

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Hello everyone. My 2021 JL Jeep Wrangler Unlimited Rubicon is the very first Jeep that I have ever owned and so far I am loving it. When I ordered my Jeep, I ordered it with the 3.6 liter V-6 with eTorque and the 8-Speed Automatic 850RE Transmission. After the engine, transmission, transfer case and front and rear differentials all get a chance to break in, I plan on putting Amsoil synthetics in everything.

I will do my engines motor oil changes at about every 2,500 to 3,000 miles but when my Jeep gets to around 10,000 miles to 15,000 miles put on it, I will then go and put Amsoil in the front and rear differentials, transfer case and automatic transmission.

I was curious if anyone else in here has done the same exact thing? I know that at every automatic transmission fluid change on these transmissions that the filter is integrated into the pan so I was curious if the entire fluid from the transmission, including inside the torque converter, if everything drains back into the pan when the vehicle is not running? I also know that the transfer case also takes automatic transmission fluid too. But I’m assuming that the transfer case is a totally separate system from the transmission. Or in other words, it takes its own fluid and does not share fluid from the automatic transmission right?

Any help and advice would be very much appreciated!
Thanks.
The brand of oil is not as important as using an oil with the correct specification that meet/exceed the manufacturer's specifications for SAE, API, FCA material standards, etc. As for the German ZF transmission, dropping the pan and filter will not drain all of the ATF. Some oil will still remain in the valve body and torque converter, thermostat valve, cooler and cooling lines. Dealers have a flush machine that will do a nearly complete flush. Also, the filling procedure to obtain the correct fill level on the ZF transmission is not straight forward.

Watch this video to see the correct procedure for checking the fluid level:

Check ATF Procedure

At 2,000 miles, I did my first engine oil/filter (diesel) change and at 10,000 miles I changed the front and rear differential oil and transfer case oil. I am a long way off for flushing the TORQUEFLITE 8, ZF 8HP70 TRANSMISSION, but when it is time, I will have the dealer do it since I do not have the correct equippment.
 

viper88

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I hesitate to comment in any "oil threads" on a forum, but nonetheless... As a former engine design engineer I have to make the side comment that doing oil changes every 2,500-3,000 miles is 100% unnecessary unless you are sitting idle in a dust storm all day. That is "grandpa" advice at this point, and hasn't been relevant since the 80's. (Though doing a short interval on your very first change is still a good idea.)

With modern synthetics you are perfectly fine at 10K miles in "normal" everyday driving conditions, or 5,000-7,500 if doing a lot of off-roading, towing, etc. So even under the most "safe" strategy there is no purpose to more frequent oil changes.

I've seen literally dozens of engines torn down from fleet vehicles, dyno durability tests, etc. and using synthetic oil the main bearings, for example, showed nearly no sign of wear using the above guidelines.

Let the "but oil is cheap insurance" comments begin...
It's surprising to me how people think they know more than the engineers and manufacturers who have to warranty the engines. A friend who works in the automotive world told me the same. He said follow the owners manual. He said he would not hesitate going 6K-8K miles between quality synthetic oil changes if driving cycle is normal. He also said 90% of engine wear happens at cold start ups. Synthetic oil's improved flow and lower viscosity help greatly with cold start up. He said engine air filter replacement helps with reduced engine wear under extreme use is dusty conditions.
 
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LongTimeListener

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I hesitate to comment in any "oil threads" on a forum, but nonetheless... As a former engine design engineer I have to make the side comment that doing oil changes every 2,500-3,000 miles is 100% unnecessary unless you are sitting idle in a dust storm all day. That is "grandpa" advice at this point, and hasn't been relevant since the 80's. (Though doing a short interval on your very first change is still a good idea.)

With modern synthetics you are perfectly fine at 10K miles in "normal" everyday driving conditions, or 5,000-7,500 if doing a lot of off-roading, towing, etc. So even under the most "safe" strategy there is no purpose to more frequent oil changes.

I've seen literally dozens of engines torn down from fleet vehicles, dyno durability tests, etc. and using synthetic oil the main bearings, for example, showed nearly no sign of wear using the above guidelines.

Let the "but oil is cheap insurance" comments begin...
I mean, it is cheap insurance. You are far better off changing too frequently than too infrequently.

However, based on my own research, every 3,000 miles is clearly overkill. I usually go 7,500. If the vehicle has been operating extensively in harsh conditions, I’ll do 5,000.

I acknowledge that you know more than I do, but pushing to 10k+ still makes me uncomfortable. It comes back to the “cheap insurance” point. I’ve drained some synthetic oil at 7,500 miles that was pretty dark.
 

SilverSurfer

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I want to refrain from typing a very long message so I will stick to the most important facts, based on (Thank you Isaac) thermodynamics;

1. Moving parts generates energy in the form of heat.
2. Heat degenerates oil viscosity.
3. Temperature is simply put a way of measuring heat.
4. Oil has an optimal operating temperature.
5. If the oil operates frequently above its optimal operating temperature, the life cycle of the oil is shortened.

I would highly recommend that If the oil in the ZF 8-speed automatic transmission operates frequently above 230 degrees Fahrenheit (All things being equal) then one should half the OEMs recommended replacement (In miles and not time). In other words if the recommended replacement cycle is every 40 000 miles then one should replace every 20 000 miles.

Replacing at less than 20 000 miles would be unnecessary (Considering the average operating temperature of 230 and above degrees Fahrenheit).

Note: There is no such thing as a "sealed for life" transmission.
 

Rogue Toad

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It's surprising to me how people think they know more than the engineers and company who have to warranty the engines. A friend who works in the automotive world told me the same. He said follow the owners manual. He said he would not hesitate going 6K-8K miles between quality synthetic oil changes if driving cycle is normal.
Yes. Keep in mind that there is basically zero incentive for automotive companies not to error on the safe side and tell you to change the oil MORE than is strictly necessary. Even in the instances where the maintenance is "included" (you are paying for it somehow anyway), they don't want to be replacing engines or even get a reputation for problems.




I mean, it is cheap insurance. You are far better off changing too frequently than too infrequently.

However, based on my own research, every 3,000 miles is clearly overkill. I usually go 7,500. If the vehicle has been operating extensively in harsh conditions, I’ll do 5,000.

I acknowledge that you know more than I do, but pushing to 10k+ still makes me uncomfortable. It comes back to the “cheap insurance” point. I’ve drained some synthetic oil at 7,500 miles that was pretty dark.
Personally, I change every 7,500-10,000 miles "to be safe" since I know I would be fine even at 12K or more. (I do the very first one at 4k-5k.) The thing with these longer changes though is to make sure your oil level is correct. While synthetics are good for much longer mileage, it's easy not to check to see if your vehicle is burning / losing oil.

Darkness of the oil is generally a sign of age and contamination, but isn't a sign of viscosity breakdown per se. I don't much like oil that is "too dark" either, but mentally I know the synthetic is still doing fine. You are taking a reasonable approach though.
 

SilverSurfer

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Yes. Keep in mind that there is basically zero incentive for automotive companies not to error on the safe side and tell you to change the oil MORE than is strictly necessary. Even in the instances where the maintenance is "included" (you are paying for it somehow anyway), they don't want to be replacing engines or even get a reputation for problems.






Personally, I change every 7,500-10,000 miles "to be safe" since I know I would be fine even at 12K or more. (I do the very first one at 4k-5k.) The thing with these longer changes though is to make sure your oil level is correct. While synthetics are good for much longer mileage, it's easy not to check to see if your vehicle is burning / losing oil.

Darkness of the oil is generally a sign of age and contamination, but isn't a sign of viscosity breakdown per se. I don't much like oil that is "too dark" either, but mentally I know the synthetic is still doing fine. You are taking a reasonable approach though.
You change the transmission fluid every 7500 - 10 000 miles?!?
 

FloridaLarry

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Lets separate facts from conjecture. The cleaner (newer) the oil, the less engine wear. Oil deteriorates slowly from the moment you change it until you moment you dump it, each mile offering slightly less wear protection than the pervious mile. Thus, all things being equal, the more your engine runs with clean oil (the more intervals), the less wear it will have. There is no mechanical downside to changing 'too often'.

The argument some keep making is that the difference in wear between 3K, 5K, and 10K intervals is so minute that the long term wear difference is a non-factor, so why waste the time and money? They say the increased wear will be within the tolerance of the parts so performance it maintained throughout the useful life of the engine, or... if the engine 'only' lasts 200,000 miles instead of 250,000 is a moot point since the Jeep will be crushed for scrap at 175,000 miles, for example.
 
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J.Ralston

J.Ralston

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Lots of good information here and I appreciate everyone’s input. Where I live at now we have winters that can see temperatures go well below zero but that average winter high are probably in the 20’s to 30’s. In the summer time we get temperatures in the high 90’s to low 100’s and have a decent amount of humidity.

With my Jeep, this is the first vehicle that I have owned that calls for 0W-20 motor oil but since it does, that is what I’ll use.

I’ve always preferred to do oil changes early because it seems like even after using full synthetic motor oils and quality OEM filters, (I will never use a Fram) that the oil start to darken and get dirty around the 3,000 mile mark, which also means less protection because the oil is starting to break down.

Back when I was doing 60,000 miles a year in my trucks, and they were hard miles too, I liked having the little extra security.

Now, I only drive maybe 5,000 miles a year to maybe 6,000 miles a year. But like someone in here mentioned, the most damage is done during cold start ups. And with us having very severe winters, combined with the fact that I am literally doing and oil change only once every 5 or 6 months due to how few miles I now put on my vehicles, I still don’t have an issue with doing an oil change only about twice a year.

With the other fluids, I prefer having trusted synthetic fluids in the vehicle. But with the automatic transmission, if I have to take my Jeep to the dealership to have the Amsoil put in it so everything can be fully flushed first, I also don’t have a problem with having them do that just as long as everything is done right.

I also wasn’t trying to suggest that I know more than the engineers who designed and then built the drivetrain components. Clearly they do know more than me when it comes to these sort of things but with vehicles getting more and more expensive every single year, I want to do everything that I can to make mine last as long as it can. Although I sure do miss the simplicity of vehicles from times past.
 
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