I brought my new to me 2006 R52 S JCW in for a check up from what I was told was a local garage that had lots of experience with Minis. I bought the car as a project to learn about fixing a car, and figured I would start down that journey by getting a professional opinion on what needed to be done on the car. All good and they picked up a few things that I should tackle, including a leaking power steering reservoir, and he topped up the reservoir and sold me the rest of the 1L bottle to keep it topped up until I fixed the leak. So for the last year I have been topping up the power steering fluid until I got around to fixing the problem (did as part of dropping the subframe to replace worn bushings and more), and used up the last of the bottle to almost fill the the power steering reservoir.

What the shop topped up my power steering with and what I have been using for the last year is Pentosin ATF 6. On further reading (and in the Bentley Manual in all caps letters) I only should have been using the Pentosin CHF11S power steering fluid, and the ATF fluid will wreck the seals.

At this point, should I pick up a couple liters of Pentosin CHF11S and try to flush the power steering pump and lines? or is the damage done and just keep filling with the Pentosin ATF 6 fluid?

Any insight would be helpful, ideally I don't want to be replacing the power steering pump and lines.

Sidenote, the forums here and ModMini videos were indespensible in dropping the subframe and doing a refresh of the bushings and suspension this summer (although I will admit every 1 hour job takes me about a week to do, but I am learning).

 

Hello.

Here is all the info, it happens sometimes when they dont select the correct fluid. Time to do the flush asap.

https://www.northamericanmotoring.co...ering-res.html

 

Yes flush it asap.

For those in Europe, Pentosin CHF11S is not available. Instead I use Febi Billstein CHF11S and it has been working great for the last 6 years in 4 different Minis.

 

^^^DITTO^^^
When my PS lines started to fail (back in 2017) losing a ton of fluid per day, I'd made the same mistake topping off the fluid tank with ATF every so often for about a week.
I quickly made it a point to change the lines and flushed the system when I'd also discovered the mistake of adding the wrong type of fluid. I purchased 2) liter cans of Pentosin CHF11S. @ $19/can back then - I still have 1-1/2 liters sitting around. After 7 years, since then, My PS is still functioning perfectly but has just started to leak again at the upper hose clamp.

 

Pentosin CHF11S is available in Europe, except it's been renamed Titan a few years ago (no clue why). It's still, as far as I know, the same fluid.

You can also use Motul Multi HF, which is much cheaper but does have the required BMW specification to be used as CHF fluid (I've double checked, because it wasn't marked compatible in the parts store system that I bought it from, but it's the same green color and have the BMW spec written on the bottle).