Did you know that all Gaydon era Aston Martins (DB9, Vantage, DBS, Vanquish) use a hydraulic power steering system like many modern cars.  Since it is hydraulic, that means it has hydraulic fluid, or more commonly described as Power Steering Fluid.   Like any fluid in your car it can break down or leak away, so checking the fluid level should be part of every Annual Service.  If you discover that the fluid level is low, the next question is what do you top it off with?  Early model DB9’s even have an issue with the original fluid they used.   Read on to learn what the correct fluid is and what the issue was with early cars.

Aston Martin’s Recommendation

The place I always start is to see what Aston Martin recommends as the correct fluid.   If you open the Glove Box and pull out your owners manual and look at the Fluid Specification Page you’ll see for my early car, a 2005 DB9 Coupe they are recommending Texaco Cold Climate.

Don’t stop reading yet, this isn’t the fluid you’ll want to keep using as it has a problem.

I also wanted to check the official Aston Martin Workshop Manual to see what they are instructing their Service Technicians to use.  Section 11.02 describes it clearly as 33270 Texaco Cold Climate Power Steering Fluid 14315G.  Again, don’t stop reading yet, Aston Martin changes their mind.

Aston Martin Field Service Bulletin SB-11-0300

In April  2010 Aston Martin published Field Service Bulletin SB-11-0300 to all their dealers to warn them of an issue where cars were experiencing a perceived ‘Squeak from the Steering Column’ and ‘Steering Judder’ when the car was cold and the steering was turned at low speed.   For example, backing out of the garage on a cool morning and your steering is heavy and juddering (pulsing, jerking a bit) as you turn the wheel.   The issue goes away as the car warms up or the weather warms up.   My car definitely experienced this issue on colder days.   You can read the FSB article here.

According to the FSB it applied to vehicles:

• DB9 up to vehicle number A12418
• V8 Vantage up to C13358
• DBS up to E01351

[Your vehicle number is usually the last 6 digits of you VIN number – My 2005 DB9 Coupe is A01906 and is one of the affected cars]

It basically describes that they believe the issue is caused by the original Texaco Cold Climate Power Steering Fluid not performing well.   The bulletin recommends that the fluid be flushed (using the highly detailed procedure in the bulletin) and replaced with a different Power Steering Fluid, Pentosin CHF 11S and an extra Lubrizol additive.

Why did they use Texaco Cold Climate fluid in the beginning?  I suspect that it was the influence of Ford (who owned Aston at the time).  You’ll note on the fluids page the engine coolant is also made by Texaco.  I suspect Ford had a deal with Chevron/Texaco to use only their fluids in Ford vehicles.   May not have been the best fluid for the job in this case as the FSB points out.  If you search for this fluid today, it’s pretty obscure.  I found this link to the Chevron Product Data Sheet that has details about the Texaco fluid.   If you are actually keen to buy some, I only found it available as a Land Rover bottled product (Ford owned Land Rover back in 2005 as well).  Just as well we don’t need to purchase it anyways.

I can’t confirm this, but I suspect on later model cars (after 2010?) the owners manual will be recommending Pentosin.   If you find that this is true for your car, can you please leave a comment below and what it recommended and what model/year your car is.   I’d like to share this with other readers to add to their confidence.

Pentosin CHF 11S

Pentosin CHF 11S power steering fluid is a VERY popular choice in many modern cars.  It is NOT a bespoke fluid made specifically for Aston Martin.   My son’s 2006 Mini Cooper S uses it.  My Sweetie’s 2016 VW GTI uses it.   And now you know your Aston Martin’s use it.

Pentosin is a quality brand.  CHF 11S is widely available (since its used in so many vehicles) and this is a great thing since it will be more widely available and hopefully less expensive.  You can learn more of the details about its properties by reviewing the official Pentosin Product Data Sheet here.

You can get a 1 liter can of it in many places like:

• Local auto parts store like Napa Auto Parts for $24.29 USD per 1 liter can
• Online from Amazon.com for $23.30 USD per 1 liter can with free shipping

If you are going to flush your power steering system it holds about 1.3 liters total.  You should probably get two 1 liter cans and then you’ll have a little left over to top up the fluid in the future if needed.

Alternatives

I’m not sure why you’d entertain alternatives when the correct fluid is abundantly available and inexpensive.

In a pinch I would look for power steering fluid from a recognizable quality brand like Castrol, Motul, Liquid Moly, Prestone or others.

In the old days American cars used Automatic Transmission Fluid as power steering fluid.  I get it, the are both hydraulic fluids so it should work.  It probably would in a pinch, but why risk it.

Mixing Fluids

To me I don’t think its a great idea to mix brands of fluids.   In a pinch if you are on a road trip and suffer some issue with your power steering and find you are low on fluid, you could probably top off with any power steering fluid.  But, when you get home I would recommend solving your leak (that cause the low level issue) and then doing a fluid flush and fill with new Pentosin CHF 11S (and the Lubrizol additive).

If you have an early car and are NOT SURE if your car has been upgraded to Pentosin (as recommended in the Service Bulletin) I suggest you opt to do a power steering fluid flush and refill as part of your next annual service.  Then you can be sure you’re running the best possible fluid.

Aston1936’s Recommendation

Since it’s abundant, inexpensive and recommended by Aston Martin the best fluid to use is Pentosin CHF 11S.

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Video

If you’d like to see me chatting with Mike from Bamford Rose, an Independent Specialist Aston Martin Service Center in the UK, about what they use for their customers please check out this video: