Adding fluid to transmission

I have a zf8 and I recently had a small leak in my oil cooler line. It's since been fixed, but I plan on topping the fluid back up. I'm estimating it's less than a liter lost.

The D6 fluid by redline is readily available to me, does anyone know if it's an issue to add the D6 fluid to the existing OEM transmission fluid?

It is compatible but also risky as it has been proven to be too slippery in some zf8's, I'd use maxlife multi vehicle instead, also compatible.

Burla said:

It is compatible but also risky as it has been proven to be too slippery in some zf8's, I'd use maxlife multi vehicle instead, also compatible.

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By valvoline? Interesting, good to know. Saw that and just glossed over it assuming it was too "mainstream" for these transmissions!

Thank you

Most likely due to the operating temps of these transmissions close to oem is what works. The better fluids survive the heat, and in this case it has been too slippery in some transmissions. You can read more here, oem zf8 is actually pedestrian fluid, redline d6 is not. I use d6 in my rav 4 and it works great, c+ in my rfe better then great, but many guys on this board have had issues with d6 in zf8 only. Now, also guys run d6 w/o issue in zf8, but enough have reported slippery I say why risk it. zf8 oem fluid and maxlife line one in base fluid charts bottom graph, redline is line 2 and 5, see link. It is too bad because d6 has great properties in hot and cold that could potentially save some transmissions. But for lack of better words, the fluid is too good for the z8.

base fluids

I second the maxlife over D6. Or just grab a quart of the OEM magic juice if you dont plan to do a fluid change

dork17 said:

I have a zf8 and I recently had a small leak in my oil cooler line. It's since been fixed, but I plan on topping the fluid back up. I'm estimating it's less than a liter lost.

The D6 fluid by redline is readily available to me, does anyone know if it's an issue to add the D6 fluid to the existing OEM transmission fluid?

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You need to use ZF fluid, costs too much, but trust me (200k+ miles) it is worth it.

I'm also about to replace some transmission oil and am put off by the process (temp taking and all) of doing so. My 3.6 has unobstructed fill and drain plugs. Can I just check fill plug can be removed, remove the drain plug, capture and measure all fluid that exits, reinstall drain plug, remove fill plug and then pump the same amount of fresh maxlife multi vehicle back in then replace fill plug? I know it's not a full refreshing, however, if I do this twice more every 3000 miles I should be doing some good.

Can you? Sure. Is it the correct way to do it? Nope. If you're going to the trouble to change the fluid and filter (you should do that too) you'll never know exactly how much came out, or if the guy before you put the right amount in.

Follow the procedure exactly, paying attention to leveling the transmission . Use the temp display on the dash to monitor trans temp, so no big deal with that.

stooler said:

I'm also about to replace some transmission oil and am put off by the process (temp taking and all) of doing so. My 3.6 has unobstructed fill and drain plugs. Can I just check fill plug can be removed, remove the drain plug, capture and measure all fluid that exits, reinstall drain plug, remove fill plug and then pump the same amount of fresh maxlife multi vehicle back in then replace fill plug? I know it's not a full refreshing, however, if I do this twice more every 3000 miles I should be doing some good.

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Yes, you can but take note that the vehicle has to be running with the transmission in Park when you add the new fluid back in. With the vehicle off the torque converter drains and you get a lot of old fluid out. During refill if the truck is off the torque converter doesn’t fill and you’ll never get the amount you drained out back in.

stooler said:

I'm also about to replace some transmission oil and am put off by the process (temp taking and all) of doing so. My 3.6 has unobstructed fill and drain plugs. Can I just check fill plug can be removed, remove the drain plug, capture and measure all fluid that exits, reinstall drain plug, remove fill plug and then pump the same amount of fresh maxlife multi vehicle back in then replace fill plug? I know it's not a full refreshing, however, if I do this twice more every 3000 miles I should be doing some good.

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Why not do it properly,as stated,replace the pan and filter. Cheaper and easier to do it right,then risk hurting the transmission,and then having to buy a new one.The 8 speeds aren't exactly cheap to replace,so suck it up,and do it right.

Wild one said:

Why not do it properly,as stated,replace the pan and filter. Cheaper and easier to do it right,then risk hurting the transmission,and then having to buy a new one.The 8 speeds aren't exactly cheap to replace,so suck it up,and do it right.

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^^^^^THIS!!!!!!!!!!!!!!!!
Listen to sage and experienced advice!

You have convinced me to do it right. Since my 2018 Ram is new to me, is there any way (visually) to tell it the transmission pan/filter has already been changed out? It has 185K on it, very well kept and runs flawlessly.

stooler said:

You have convinced me to do it right. Since my 2018 Ram is new to me, is there any way (visually) to tell it the transmission pan/filter has already been changed out? It has 185K on it, very well kept and runs flawlessly.

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Carfax report might tell you,but i'd guess it's probably never been done. You can also look close at the bolts on the pan,and see if they show any signs of having a socket on them.