ZF S5-42, S5-47 Fluid Replacement

How to Replace the Fluid in a ZF 5 Speed Manual Transmission

The ZF S5-42 and later S5-47 five speed manual transmissions were used in Ford diesel pickups from 1987 to 1997. Few 6.9L IDI engines were made available with the ZF 5 speed, but it was standard issue for the 7.3L IDI and 7.3L Power Stroke during these model years. The transmissions are known to be rugged and bulletproof, the only major concern being synchro wear. The ZF 5 speed requires synthetic MERCON ATF for lubrication, rather than thicker gear oils. Failure to use the proper fluid will result in reduced performance and possibly premature wear. Changing the fluid periodically is imperative to the reliability of the transmission, and should only take you about 15 minutes once you've got the process down.

Applicable Model Years: 1987 to 1991 Ford F-Series
Applicable Transmissions: ZF 5 speed S5-42 & S5-47
ZF S5-42/S5-47 Fluid Spec: Synthetic MERCON ATF or Castrol TRANSMAX-S ATF
ZF S5-42/S5-47 Fluid Capacity: 3.38 quarts


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ZF 5 speed transmission fluid

• The ZF 5 speed manual transmission calls for 3.38 quarts (3.2 liters) of synthetic MERCON ATF (Ford part number E6AZ-19582-B) or Castrol TRANSMAX-S ATF. Yes, this manual transmission requires the use of automatic transmission fluid due to its tight design tolerances. Thick gear oil is not compatible with the transmission and will cause poor performance, premature wear, and/or driveability issues.

ZF 5 speed drain and fill plug locations

• Park the vehicle on level ground before attempting to change the fluid.

• Locate the transmission's drain plug and fill plug (see image at left if in question). Place a drain pan beneath the transmission and remove the drain plug and then fluid fill plug using a 7/8" wrench.

• Once the fluid has drained completely, reinstall the drain plug.

Filling the transmission with fluid

• Use a fluid transfer pump to fill the transmission with fresh ATF. The correct fluid level is up to the fill plug hole - when the transmission has reached the correct fluid level, ATF will begin to run out of the fill plug opening. At this time, remove the hose for your transfer pump and reinstall the drain plug.

Amsoil synthetic ATF for ZF 5 speed manual transmission

• We've chosen to use Amsoil's Signature Series multi-vehicle ATF for this transmission. This high quality fluid gave us smoother shifts and the peace-of-mind that our gear box is protected by one of the best names in performance lubricants. Though it is a multi-application fluid, it is completely compatible with any manual gear box that requires ATF.