Just wanted to know thoughts on brand of brake fluid for our vehicles. Is it okay to use any good quality Dot 4 type brake fluid in a 98 S70? I know the cadilac of brake fluid is ATE Dot 4, but is it really needed? Thinking of using Napa Dot 4, in replacing a frozen caliper. Thanks to all.

Yup, seemed the drivers side rear caliper froze up, which over time warped the rotor. Replaced that caliper, and both rear rotors, pads. We are good to go now. Thanks to Klaus and all.

Just to be sure, is the brake line end that goes into an ATE rear caliper for the S70 sae or metric thread? and what diameter?

well, I just replaced the drivers side rear caliper. It did seem frozen, so I thought this would correct my problem. It didn't. I still get a shudder rotor pulse when hitting the brakes at 50-60 mph. I replaced the front rotors, pads 6 months ago. Have no idea why the rotors would be worped at this time. Is it possible, this had something to do with a wheel speed sensor and abs? I am not getting any codes for this. I plan on buying a cheap caliper, and checking out of round/worp on all the rotors, but I still don't believe this is the problem.
Any thoughts? Klaus? Should I pull all the wheels, and clean the wheel speed sensors?

Did YOU replace the front rotors or was it a shop. I was just thinking about my project 850 which had shuddering brakes at higher speed:

I loosened the lug bolts and torqued them to 81 lbs. No more shuddering! A few of those lug bolts were a bear to get loose.

If you use a shop, buy yourself a torque wrench and always store it at zero pounds, and get a deep well 19mm socket for the lug bolts. Never use a torwue wrench to loosen nuts/bolts.
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My back feels better when I sit in a Volvo seat

Klaus, yup all at 81 ft lbs. I bought a dial indicator, and measured all 4 rotors. The fronts were all with in spec for run out. The rear drivers side rotor (where I replaced the frozen caliper) was out .04+ is some spots. I am going to replace both rear rotors. I think the frozen caliper warped that rotor at some point, and that is what is causing my shudder on braking at higher speeds. Hopefully that finishes it. I never felt the shudder in the stearing wheel anyways. Thanks again for the advice.

I had some weird shudder when braking at speed, and it turned out to
be the first clue that my left lower control arm/ball joint was going bad.

You can compare boiling points of DOT4, the higher the better.
Better still flush the fluid every two years or sooner if you have severe service.

Bill

I have replaced the left lower ball joint/arm last year. I checked the right, and it seemed tight. I cleaned both front rotors and pads as Klaus had suggested. It seemed maybe a little better, but still getting a "rotor rumble" when braking, more so at high speeds. I used a stationary dial type caliper, and both front rotors were well within tolerances, so my front rotors are not warped. Is there any chance the tires could be doing this? I do not get any shimmy in the steering wheel, while driving or braking. It is time to rotate tires, they are a very good brand. After driving all wheels seemed warm to the touch, with none really more than the others. I don't know what to do next. Any suggestions would be appreciated. Thanks!!

A bad tire can do that yes. Rotate front to back to see if it's a bad tire.

Make sure the tires have the same air pressure.

Don't assume that the new control arm is OK, check that one too.
I had one fail almost immediately.

Bill

It's not the speed sensors, don't go there.

Rotors seldom "warp". Usually it is a buildup of pad material on the rotor. And I would suspect the front brakes and not the rear, unless the vibration is definitely coming from the rear.

I found that cleaning the pads and both sides of the rotor with brake cleaner did wonders for 'warp'.
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My back feels better when I sit in a Volvo seat

What counts is the DOT4. ATE is not that expensive, but NAPA works.
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My back feels better when I sit in a Volvo seat