98 V70 power steering - fluid recommendations

Post by **98v70dad** » 15 Sep 2016, 13:26

The fluid in my power steering reservoir is absolutely filthy. Its dark brown. I'm going to flush it this weekend. Other cars I maintain have you flush the fluid at around 75,000-100,000 miles. The owners manual for the 98 V70 indicates to just use "ATF" and to keep it topped up. Dex III is what I've seen others on here use. What got me looking into flushing the fluid and changing it out is symptoms Im gettingthat match up with having some air in the fluid. I understand that ATF tends to take on air bubbles more than some of the specialty hydraulic fluids and it got me wondering if the ATF callout in the manual was a mistake. In later model years they changed the required fluid to something other than ATF which makes me wonder - would you get just ordinary ATF in the PS reservoir in a 98 V70 if you took it there today to be serviced?

Has anyone installed a magnet/filter in the return line to keep the nasties out of the rack and the pump? Its actually a little late for that now, but my car has relatively low mileage for its age so it might be worth the small expense of money an time ... an easy modification.

kippster41493 · Post by **kippster41493** » 15 Sep 2016, 13:57

I've never had experience with this, but the seals may be designed for ATF. "Hydraulic oil" is a very loose term in sense not all if it is designed the same way. It could seep past the seals, or be too thick for it to run through efficiently. The only reason I can see ATF "commonly" pulling in air is because it gets old and breaks down like any other fluid in the vehicle so I wouldn't 100% worry about it happening when you flush it out and put new fluid in there right away anyway. Another possible cause being the lines maybe cracked and is sucking in air/ moisture just like a brake line, or seals could be bad as well. I imagine any other fluid will do the same eventually. Just my 2 cents, correct me if I'm wrong though I'm curious to learn.

Post by **98v70dad** » 15 Sep 2016, 14:10

kippster41493 wrote:I've never had experience with this, but the seals may be designed for ATF. "Hydraulic oil" is a very loose term in sense not all if it is designed the same way. It could seep past the seals, or be too thick for it to run through efficiently. The only reason I can see ATF "commonly" pulling in air is because it gets old and breaks down like any other fluid in the vehicle so I wouldn't 100% worry about it happening when you flush it out and put new fluid in there right away anyway. Another possible cause being the lines maybe cracked and is sucking in air/ moisture just like a brake line, or seals could be bad as well. I imagine any other fluid will do the same eventually. Just my 2 cents, correct me if I'm wrong though I'm curious to learn.

I'm not in a hurry to change it to something else, but I've read that others have tried Mobil 1 synthetic ATF with good success. I've also wondered about using synthetic ATF blend for older cars since it might help the aging seals. I have some of that left over from a transmission flush just about a month ago.

When the 98 manual was written ATF was a very limited number of choices. Today there are many to choose from

kippster41493 · Post by **kippster41493** » 15 Sep 2016, 14:56

98v70dad wrote: I'm not in a hurry to change it to something else, but I've read that others have tried Mobil 1 synthetic ATF with good success. I've also wondered about using synthetic ATF blend for older cars since it might help the aging seals. I have some of that left over from a transmission flush just about a month ago.

Makes sense, should act the same as synthetic blend oil so I don't see why it wouldn't.

Post by **tryingbe** » 15 Sep 2016, 18:16

I use synthetic ATF.

Post by **erikv11** » 15 Sep 2016, 18:19

I use Mobil 1 synthetic ATF.

Post by **98v70dad** » 16 Sep 2016, 18:05

Since my system is so dirty I decided to go with the walmart supertech and flush a lot of it through. I bought a gallon since they were all out of quarts. After a few weeks I'll flush it again and pu tin something better that has seal conditioners for older cars.

Post by **98v70dad** » 17 Sep 2016, 15:43

So today I ran thru several reservoir's full of fluid thru to flush the system. On the last one I put in about 3 oz of ATP AT-205. I took it out for a high speed drive and although the vibration isn't completely gone it is dramatically improved and almost gone. I'm shocked. We'll see how the commute goes Monday.

The problem with an old car is that there may be several things contributing to the issue which makes troubleshooting more difficult.

Post by **shiloh51933** » 18 Sep 2016, 08:11

Pentosin CHF PWS fluid, comes in a rectangular green or silver can.

Post by **98v70dad** » 18 Sep 2016, 17:18

shiloh51933 wrote:
20160918_103108.jpg
Pentosin CHF PWS fluid, comes in a rectangular green or silver can.

Thanks but too late. I already flushed it yesterday morning. The Petosin is what I was thinking of ending with. I flushed with cheap stuff and will end with something better. Do you use petosin in a 98 model car? The 98 only calls for ATF. I posted this thread hoping to find what people have had success with in a 98 that exceed the minimal requirements of ATF.