ZF Lifeguardfluid 8 ATF, 7-Liter Service Fill for 8HP70

Shopping for fluid for an 8HP70 in a Ram 1500 Hemi, a Grand Cherokee, a Charger or a BMW 5 Series usually ends with a cart full of single liters and a trip back to the parts counter halfway through the fill. This pack is seven sealed 1-liter bottles of ZF Lifeguardfluid 8, ZF part number S671.090.312, the fluid ZF approves for the main 8HP family. Seven liters is what a pan-and-filter job actually goes through once you count what stays in the old pan and what you spill.

What Lifeguardfluid 8 does in a ZF 8HP

The 8HP does not use a band or a one-way clutch to time its shifts. Every gear change is two clutches trading load under electronic pressure control, and the transmission learns how long each clutch takes to fill. That only works when the fluid's friction and viscosity stay where the calibration expects them. ZF's data sheet describes Lifeguardfluid 8 as a semi-synthetic fluid made for these units, and warns that other oils can cause anything from poor shift quality to transmission failure. In practice, a generic multi-vehicle ATF shows up as converter lockup shudder at light throttle and flares on the upshifts, which then sends the adaptations out of range.

Symptoms of worn or wrong fluid

• Shudder or a rumble-strip feel when the converter clutch applies around 35 to 50 mph
• Harsh engagement into drive or reverse, worse when cold
• Flared or slipping upshifts, often 2-3 or 3-4
• Dark fluid with a burnt smell
• Fluid weeping from the overflow after a long drive, which usually means the level was set at the wrong temperature

Which transmissions take it

ZF's lubricant approval list, TE-ML 11, puts the 8HP45, 8HP50, 8HP51, 8HP55, 8HP65A, 8HP70, 8HP75, 8HP76, 8HP90 and 8HP95 in the Lifeguardfluid 8 group, along with the 6HP28AF. The Chrysler-built 845RE is an 8HP45 and the Hemi and diesel trucks run 8HP70 or 8HP75, so 2013-and-up Ram 1500, WK2 Grand Cherokee, Charger, Challenger and 300 with those units are covered, as are the BMW F-chassis cars on the 8HP45 and 8HP70. Two cautions. The 8HP60, 8HP80 and hybrid units sit in a different group, so read the variant off the transmission tag. And for the later 850RE, FCA's bulletins call for Mopar 68218925AB, so follow that. Our ZF 8HP fluid type and capacity guide lays out the full cross-reference. Parts for the family are on our ZF 8HP parts page.

How to confirm it is a fluid problem

Pull the fill plug and look at a sample before you spend money on hard parts. Dark, smelly fluid with a shudder complaint is a fluid service first. If the unit slips under load, will not engage, or has clutch or solenoid codes, fresh fluid will not put friction material back. The Ram 1500 8-speed fluid change guide covers the truck-specific checks and costs.

Install notes

• Shake each bottle for at least 15 seconds before pouring, as ZF's data sheet instructs.
• Start cold. The level is set by overflow at the fill hole inside a temperature window, 30 to 50 C for most units in ZF's filling specification, with exceptions for BMW, hybrid and some other applications. Overshoot it and you have to cool down and start again.
• Fill with the engine running in park until fluid just runs out of the fill hole, then fit a new plug seal and torque the fill plug to ZF's 35 Nm spec for the common 8 mm hex plug.
• On plastic pans the filter is built into the pan and the bolts are only 10 Nm. Over-tightening is the usual leak after a first-time service. A BMW 8HP pan and filter kit pairs with this fluid on those cars.
• If the cooler or lines were opened, budget close to an extra liter for the cooler circuit. A leaking 8HP70 transmission cooler should be replaced in the same job.
• Add nothing to it. ZF's service information says additives alter the fluid's chemistry.

Is seven liters enough for an 8HP70 fluid and filter change?

Yes for a normal pan and filter service. A pan drop drains roughly 5 to 6 liters, and the rest stays in the converter, clutch circuits and cooler. Buy more if you opened the cooler lines or plan a second drain and fill.

Can I use this in my 845RE Grand Cherokee or Ram?

The 845RE is an 8HP45, and ZF's TE-ML 11 list places the 8HP45 and 8HP70 in the Lifeguardfluid 8 group. For the later 850RE, follow FCA's bulletins, which specify Mopar 68218925AB.

Can I mix this with what is already in the transmission?

Topping up an 8HP45, 8HP70 or 8HP90 that already runs an approved Lifeguardfluid 8 equivalent is fine. Do not mix it into a unit filled with a generic ATF; change the fluid instead. Never add additives.

How do I set the level correctly?

Engine running, selector in park, fluid inside ZF's temperature window (30 to 50 C for most units). Fill through the side plug until it just trickles out, then install a new plug seal. Use a scan tool for the temperature.

What should I replace with the fluid?

On most units the filter is built into the plastic pan, so the pan is replaced with the filter. Fit a new fill plug seal, and replace cooler line O-rings if they were disturbed.

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