How to choose the right power steering fluid

Using the right power steering fluid is critical to the long life of your power steering components

Cardone, the largest power steering pump rebuilder, has issued a service bulletin warning about the damage caused by using the wrong power steering fluid. It’s important to note that not all fluids are alike. In fact, despite what you see on the bottles of P.S.fluid at the auto parts store, there is no “universal” P.S. fluid. Some car makers recommend a specific transmission fluid, while others require a synthetic P.S. fluid that meets a different specification. So, the takeaway is to always use the right fluid when topping off or flushing the P.S. system.

Why Cardone’s started testing power steering fluids

Cardone encountered a situation where a shop replaced a customer’s power steering pump multiple times using Cardone’s rebuilt pumps. Each time, the power steering was noisy, and the fluid temperature ran close to 320°F, way above the normal 180°F temperature range. The shop then switched to a different fluid, and the problems disappeared.

In further testing, Cardone discovered that using the wrong power steering fluid caused pump damage in as little as 20-30 minutes. This image shows the scoring on the pump shaft from using the wrong fluid.

This image shows power steering pump damage from using the wrong power steering fluid

P.S. fluid properties

P.S. fluid specifications vary based on the fluids’ viscosity, detergents, additives, and other components of the fluid. Meeting these standards ensures the fluid is safe for a specific vehicle.

Fluid specification standards are created by standardization organizations. For example, DIN 51 524T3 is the standard given by the German Institute for Standardization, while ISO 7308 is the standard given by the International Organization for Standardization.

Certain vehicles require power steering fluid to meet DIN 51 524T3 and ISO 7308 standards. There may be other power fluid standards for certain types of vehicles, like those made by Japanese automakers.

In addition to using the correct fluid, all car makers advise against using a P.S. fluid with sealers and conditioners. These fluids can clog delicate flow control valves and tiny orifices in the pump and the power steering gear (rack), causing far more damage than you would incur if you just fixed the leak the right way.

Stay away from fluids containing stop-leak additives

As tempting as it may sound, P.S. fluid leak sealers and conditioners rarely work. The power steering pump generates upwards of 2,000 psi, and no chemical sealer can possibly stop a leak when under that kind of pressure. Seal conditioners work by causing a hardened seal to swell. So you may get temporary improvement in leak stoppage, but the swollen seal will fail due to its softened state.

Finally, most car makers do NOT recommend P.S. flush procedures. This is important as many shops push these expensive services to improve profit. Clear P.S. fluids will turn dark grey after use. That does NOT mean they must be flushed. If the shop recommends a P.S. flush, consult the manufacturer’s maintenance guide before agreeing. If it’s not listed by the manufacturer, DON’T do it.

There’s no such thing as a Universal P.S. Fluid or a Multi-Vehicle power steering fluid

Here’s a small example of the different power steering fluids required by Audi and GM

Audi/VW P/N G 002 000
Audi/VW P/N G 002 012
Audi/VW P/N G 004 012
Audi/VW P/N G 004 000 M2
Audi/VW P/N G 004 000 M7
Audi/VW P/N G 004 000 M8
Audi/VW P/N G 055 145 S2

GM P/N 89020661
GM P/N 89021182
GM P/N 89021184
GM P/N 89021185
GM Spec 9985835

Using the wrong fluid or a universal fluid that doesn’t meet the manufacturer’s specifications can destroy a power steering pump. The correct specification is listed in your owner’s manual. Write down that spec and ensure the fluid you choose lists that specification on the bottle. This is critical!

©, 2014 Rick Muscoplat

©, 2013 Rick Muscoplat