AYC Hydraulic fluid top up

[Braddy40]

I was looking to make a start on changing some fluids after reading through some of your very helpful guides. I made a start by checking the colour of the Ayc Hydraulic fluid in the reservoir which was fortunately still a light cherry colour, but the level was quite low.
Is it a simple case of topping up directly into the reservoir?
Also should I be using Amsoil ATF for this job or will Mitsubishi ATF or Dextron III be OK as I have used up all my Amsoil ATF?
I read that it is not so important to use Amsoil in the AYC clutch pack.
I realise I'm being extra cautious, I just wanted to be 100 %.

[Davezj]

the rear diff AYC system has 3 different oil systems.

1. the gears of the rear diff, requires 75W-90 Sever gear oil AMSoil is good for this.

2. AYC clutch pack in the rear diff. AMS oil ATF is the best stuff for this.

3. ther resovoir in the boot that feeds atf oil to the ayc pump. this oil system is not the same oil that is in the clutch packs in the diff they are completely separate systems and never mix.
technically any hydraulic oil can be used for the AYC pump as it is just that a hydraulic pump that produces pressure to move some solenoids/piston valves in the rear diff to compress the right side clutch pack or the left side clutch pack.
However ATF is recommended and i would not want to mix different types of ATF in the pump system. but saying that you can use dexron III and any SPIII compliant ATF, you do not have to use Amsoil ATF in this system, but i always do. as it is the only atf i use on a regular basis. i have used other ATF's in the passed. but AMSoil ATF is my ATF of choice.

[elnevio]

Any of those will be fine, as it is the hydraulic side of the system, and the not the clutch packs side (which is what gets the abuse).

[Braddy40]

Thanks for the advice Dave and Nev.
I was surprised how clean the Fluid in the reservoir was as guidelines advice changing every 6 months. The advice seems to be if its clean/light cherry don't change it. There is a very strong chance Amsoil Atf was used but as the level is safe on a second viewing I wont risk mixing.
My next stage will be the transfer, rear diff and Ayc clutch pack which as you have stated wont be so clean. I have a bottle of the Amsoil Severe oil but will have to buy more as its not quite enough for both Transfer and rear diff. I will be following the guides provided on this site. My only fear is loosening the filler bolts and not damaging the alloy threads.
Do you change all, (Transfer, rear diff and AYC Clutch pack), oils every 6 Months?

[Nick Mann]

Mitsy uk say 5 years or 45k miles for the gear oil parts.

[Braddy40]

Good news ,Thanks!

[eyeballprawn]

If you check the AYC reservoir level after driving it will be low on the dipstick due to the fluid being pumped into the system. You will probably find it's not much higher than the filter mesh.

The best time to check is in the morning, as it takes at least a couple of hours for the pressure to subside. If you have Evoscan you can use a function on that to reduce the pressure too.

If you don't wait until the pressure has subsided and top it up then you will overfill it. Then when the pressure drops the fluid will rise up and force its way past the cap, leaking into your rear-quarter area and sometimes dripping down past the grommet onto the ground.

If you have already topped it up, check it again one morning and remove any excess fluid.

[Braddy40]

Thanks for the info Dylan. A very useful and important point. Fortunately I did give the level a check when it was cold as I would with other oil levels and this is when I discovered my level was OK. As you pointed out, I could have overfilled it.
Sorry, another quick question. As the diff and trans oils only have to be changed every 45,000 and the AYC hydraulic every 9,000 should I change the AYC clutch pack every 9,000?
I can remember seeing a very useful guide on this site with service times but I can not find it again. I have found a downloadable file but my computer does not have the software to open it.

[Nick Mann]

I'm on my phone, so a direct link is tricky, but fundamentally you need to click something like members links, library, maintenance, service schedule. There is a scanned copy of a ralliart UK service schedule in there somewhere.
The ayc clutch pack fluid gets far more abuse than the hydraulic system, that is the one that needs changing most often. How often depends on how you drive.

[Braddy40]

Thanks once again Nick.