Strut leak

WARNING: This page does not describe the selected car, but rather 17 other vehicles, including the 2009 Audi S4, 2009 Audi A4, 2008 Audi S4, 2008 Audi RS 4, and 2008 Audi A4. However, it is still accessible from the selected car via links, so may be relevant.

Struts are frequently rejected and exchanged because of leaks. Examinations on test stand and on the vehicle have shown that the replacement of a large number of rejected strut was not justified.

Slight leaking of oil ("sweating") at piston rod seal is no reason to replace a strut. A strut with oil is OK under the following circumstances:

Fig 1: Identifying Fluid Seepage

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Oil leak (shown screened in illustration) is visible, but dull, matte and possibly dry from dust
Oil leak reaches at most, from upper shock absorber seal (piston rod seal) to lower spring plate - arrow -.

NOTE:

A slight oil leak is advantageous because it lubricates the piston rod seal and extends its service life. This applies to struts on front and rear axles