I took a long drive to Maryland this past weekend, and after about 3hours of continutous highway (avg 70mph) driving, I was curious about the inside of my car (don't ask why--really, nothing prompted me to do so, but I did.) I popped open the hood and I saw that the liquid in the power steering fluid reservoir was boiling (bubbling). I have noticed this in prior long drives...and I was just curious...is this a normal occurence that in long drives, the power steering fluid will get hot and bubble up (not much of a concern really) or it could be a signal to that something is wrong?
Has anyone else noticed this? I have read on a few of the posts here that synthetic power steering fluid is better in protection than regular power steering fluid or Automatic transmission fluid (used to fill up the reservoir).

anyone switched over to the synthetic and noticed a difference?

 

There is an important difference between bubbling and boiling. Bubbling means air got mixed into the fluid. I don't know what might cause this but it doesn't seem like a serious problem. Boiling, on the other hand, is definitely a warning sign. There should be little friction and therefore little heat in the power steering system. Petroleum which is hot enough to boil may be hot enough to burn, depending on the flash point of the substance. Perhaps you can use a cooking thermometer, the kind which is a temperature probe with a dial readout at one end, to determine the temperature of your bubbling/boiling power steering fluid.

 

The power steering fluid can get hot and that's why there is a cooling coil. The heat usually only becomes a problem from doing something like autocrossing which has near constant, large steering changes. Highway driving should not cause high temperatures. BTW, oil doesn't boil. Bubbles are either air coming out of the system, or water moisture boiling off.

 

You might want to check to make sure your PS cooling lines (they run on the passenger side of the engine bay, and on some Maximas, also have a tubular metal coil that runs in front of the AC condensor) are not clogged or constricted.

 

I am sorry for the confusion. I think it is more of a bubbling than a "boiling." The bubbling however only comes around when the car has been driven for a long period of time. Usually, short trips don't affect the power steering fluid reservior much, only that it expands from the "old max" line to the "hot max" line...and there isn't much bubbling. The trip that I took down to Maryland did involve a lot of turning--since a good distance was back roads...I do wonder if all that turning and etc...affected the temperature of the fluid.
So from what you guys have said, I am assuming that power steering fluid does get hot similar to transmission fluid...

everything seems to be working fine, aside from that.