I just performed the swap from ATF to Pentosin 11S. This is the first time I've disconnected the return hose from the reservoir as part of the drain/bleed/fill process (for any car). While more involved than simply removing fluid from the reservoir, filling it, running the engine to circulate, and repeating until mostly clean, the Aston-recommended process is much more efficient and effective. It does require the front wheels to be off the ground though.

Capping the reservoir return feed was no big deal, and I did not use a clamp, etc. I just used a securely-fastened hose capped with a bolt. A silicone plug should be fine as well, provided its a secure fit.

For the rubber return hose from the rack, I inserted a 4-ft section of semi-rigid vinyl hose *into* it about 3/4". Make sure this connection is secure...if it's loose and comes off, you'll have a mess. I was reluctant to use a barb, etc. to extend the line since I was paranoid it would either (a) get stuck, or (b) distort the ID of the hose, preventing it from sealing properly when reconnected to the reservoir.

The bleeding process took a bit longer than I expected, but all seems to be well now.

I'm not sure why, but the steering felt better after the change. The effect was subtle, but effort seems slightly less and feel slightly improved. After seeing what AFT can do to rubber hoses over time (I have a few old BMWs), I'm really glad to be rid of it.

 

I am planning to do power steering flush soon. I see above and in the service bulletin that you need to add lubrizol additive but all I am finding is the mercedes branded one. Is this the same as the jaguar/aston one just it is "for" mercedes?

 

It’s the same stuff. Just use the correct amount.

 

Lubrizol is available on amazon and ebay. Removes the squeal in my MB ps, so I did add to my AM.

 

Awesome thanks E30 Racer

 

My steering was very very squeaky, so I found 50mL Lubrizol 6178 from a BMW dealer for about $15. Apparently, it's pretty hard to find it now, because I called a Mercedes dealer and they said they couldn't obtain it. I don't see the MB/BMW part numbers on Amazon for example, and on Ebay or one FCPEuro/Pelican/etc the total cost is a little more thanks to shipping.

Just to see what happens, I poured maybe a quarter of the bottle into what should be factory fill ATF, and about an hour of driving later the squeaking completely disappeared. I'm going to swap the ATF to CHF-11S soon, but not sure if I even need to add the rest of the additive. If anyone in Northern California wants to try a quarter bottle hit me up lol. There's really no reason to use the whole bottle if the squeak goes away, right?

 

I found 50ml (single serving size!) readily available on Ebay. Stuff really works to remove squealing...

 

I also purchase a 50ml bottle of Lubrizol 6178 (for Mercedes) off Amazon for < $14.00

 

It appears that Pelican Parts has 50ml bottles for under $10 plus shipping. Lubizol 6178

 

This is the right stuff, CHF-11S, CHF-11(5) S. wrong part number

 

This (6178) will cross the the AM part #....

 

After changing the fluid, you'll want to put a label (Part Number: AD43-3F730-AA from Suderia $12.92) on the reservoir cap. Or, what I did, buy the entire new reservoir on ebay (Item 234285634370 $14.82) and replace the cap having the engraved "CHF-11S Only".

 

I recently changed my power assisted steering fluid since it was 8 years old. The old fluid definitely had a brown tinge to the color compared with the green new fluid and there were a few nasty black chunks that also came out.

I followed the aston1936 link to the AM manual to do the job. A few notes that others may find handy.
The rubber suspension grommets for the reservoir bracket have metal liners inside. Be sure to remove these together with the bolts or they WILL fall out during the man handling of the unit and be lost forever.
Getting the return hose off the barb was a bear. 8 years of seal took some breaking. Maybe others have a better technique, but what finally worked was rotating the hose relative to the metal barb with a pair of large pliers. Be sure to have your container in place for removal since about 50ml of fluid will remain in the reservoir.
To drain the old fluid, your assistant will need to spin the steering wheel vigorously from lock to lock, while you watch and drain the container. I could not fit a large enough container under the return hose to take it all in one go. Slow movement of the wheel will do nothing.
Maybe the experts know how to add the new fluid to the required level first time, but in my case it took 3 top ups after I thought I had correctly filled the reservoir for the level to not drop as extra air was expelled during the first few minutes of driving. I just circled my block a few times until this stabilized.

I got the oil additive from Pelican as suggested below.

Philip