what is the required power steering fluid for 2007 xj?

 

Originally, it was filled with Mobil Dexron III. That is the specified fluid (Dexron III) by both Jaguar and ZF who produced the unit. You can still find Mobil D/M which meets the Dexron IIIH spec, and is the right viscosity. It also contains the right anti-foaming additive for this usage.

 

Thanks much Box!

 

This is very interesting and confirms what I always believed to be the case. I have a Jag, BMW, Volvo and RR which all have ZF power steering pumps and racks. The boards are filled with proclamations about never using this or that power steering fluid as the seals cannot handle it. Yet here the Dexron III is the right choice.

I will wager trusty and cheap Dexron III will work in every ZF system provided a proper flush is done.

 

 

The Servotronic power steering system operates using a conventional hydraulically operated rack and pinion, equipped with a rotary valve and added electronics to control the system’s hydraulics. This system provides the driver with steering assistance proportional to the vehicle’s speed:

• with full hydraulic power assistance provided at low vehicle speeds, for example when parking the vehicle, and

• a gradual reduction of hydraulic steering assistance as the vehicle speed increases, allowing the driver a precise feel of road contact.

The operating function of the Servotonic system is explained below:

• Road speed data, as measured by the electronic speedometer is transmitted to the FEM by the instrument cluster, via the SCP bus.

• Using the variable assisted power steering (VAPS) curve data stored within its memory, the FEM calculates the amount of current needed to supply the VAPS solenoid, which is an integral part of the Servotronic transducer.

• Based on the amount of current received from the FEM, the VAPS solenoid controls the hydraulic reaction of the rotary valve.

• This hydraulic reaction determines the amount of torque (effort) the driver needs to apply to the steering wheel at various vehicle speeds. A further advantage of the Servotronic system is the fact that the oil pressure and flow are never reduced and can therefore be utilized immediately in emergencies, where sudden and unexpected steering corrections become necessary. The power steering pump is mounted to the engine and is driven by the accessory drive belt. The pump provides a constant flow rate of 7.5 liters per minute and has a maximum pressure of 110 bars. The fluid reservoir incorporates a 10-micron internal filter to ensure cleanliness of the system.

Steering Rack

The steering rack is a variable ratio design, providing ease of parking maneuverability while maintaining the on-center steering precision required at high vehicle speeds. The steering rack is a compact unit, mounted via dual-rate rubber bushes to the rear of the vehicle’s front subframe. The rotary motion of the steering-wheel is transformed by the pinion into the axial motion of the rack. The tie rods, attached at each end of the steering rack, transmit the steering motion to the wheel knuckles. From lock-to-lock the steering rack requires 2.8 turns of the steering wheel.

 

Just a bit more on fluid and fluid selection. As stated above, original fill was Mobil ATF DEXRON III, (EU market Mobil ATF 320, which is Jaguar part # JLM21703 @ >$25.00 per Liter US) and is not widely available in the US market outside of purchasing at dealer networks. It's moderately high cSt @ 100°C is 8.2, which is much higher than most newer types of ATF available out for newer specs like DEXRON VI. When tested, most off the shelf bargain basement ATF, stated to meet DEXRON III fluid specs, generally tested out to actually be over time to have a cSt @ 100°C in the 4's. (cheap fluid) This is actually a little too low for the intended purpose. ZF specifies fluid under the ZF TE-ML 09 spec (power steering units) Mobil ATF SHC which is rated at cSt @ 100°C of 7.4 and has a very modest thickening at -cP @ -40°C of only 7000, meaning its fluidity is still relatively thin at very cold temps in comparison to Mobil ATF 320 with it's -cP @ -40°C at 17,900. (thicker)

Now comes what I stated above for the Mobil ATF D/M which at cSt @ 100°C of 7.4 and at -cP @ -40°C 16.670. (at around $5.00 a quart, a high quality fluid widely available in the US market) Also available is Mobil 1 Synthetic ATF which is also DEXRON III approved with cSt @ 100°C of 7.4, and at -cP @ -40°C of 10.040, but at around double the price of Mobil ATF D/M. Traditionally, synthetics will retain viscosity better than non-synthetics over a longer period of time in change intervals.

The important take-away here is retention of the original "feel" of the steering, and since there are no clutch pack slippage issues here, just the original programmed curve in the FEM that changes it's feel, you would want to make a selection as close to the original fluid as possible as it pertains to viscosity, especially at high temp performance. Cheap DEXRON III fluids can thin too much to retain that special "Jaguar" feel of the steering components, and that is a something we as owners know all too well in comparison to all the other brands we drive out there. Happy motoring!