I've been getting random "cooland level low" errors for 5 seconds and then disappears. I suspect my level is getting to that point that its low enough that makes it seem its too low when i take hard turns

question is: do I need to flush out the system? or can I simply just add more?

Should I get the pre-mixed wather/coolant........or mix it myself?

 

Depends on your service interval. If its never been changed and you're getting near 100K miles, I'd drain and replace it but I'd be shocked if it weren't already changed every 25 to 50K miles along with each iteration of the lousy water pump (is it leaking again?).

I generally mix my own because I've always got distilled water on hand anyway and its a little cheaper. Pre-mixed is merely a premium cost for convenience as you don't need an extra container or any means to measure volume, get the job done 5 to 10 minutes quicker.

 

The "coolant level low" message is only meant to come on once the level in the expansion tank drops well below the "MIN" mark, which is usually between 1.5 and 2 litres below the "MAX" mark (the warning level that is, not the MIN mark).
You should manually check the level, just take the cap off the expansion tank and have a look.
If it's at least at the MIN mark then you probably have a duff level sensor, a fairly common problem on the XF. In turn it's often the "float" on the sensor has stopped working and adding a new float (commonly the little foam stopper on the top of a CD/DVD stack) has worked for others, search and ye shall find.
As pdupler says, if you are not sure the coolant has ever been flushed and renewed then it's possibly overdue and you should get it done.
If you are fairly sure the coolant is reasonably fresh then it may just need topping up, and make sure you use the correct spec of coolant (it's in the Owners Handbook).
No need to waste money on pre-mixed, much cheaper to buy a bottle of concentrate and mix it yourself with de-mineralised water. Either two parts water to one part concentrate or 50/50, it varies, just follow the directions on the bottle.
Last but not least, if the coolant level has dropped enough to validly trigger the low coolant warning then you may have a coolant leak somewhere, and you should urgently get it checked out.

 

Thanks for that heads up.

Im thinking it might me more of a sensor issue. I havent had a chance to check my level yet. but the message appears for 10 seconds on startup (if i leave the car overnight) and then disappears like nothing happened. if i start the car up again no error. It then also popped up once more when I took a turn aggressively...but then went away

 

Isn't the Dexcool, and similar coolant, supposed to be good for 6-7 years? So depending on the year of your car, it probably should have been completely changed at least once, by now.


I don't like to go more than 4 years, so the coolant in my '09 XF has been changed twice.

 

X2, it doesn't hurt to replace the coolant more often. It's in contact with various metals, and slowly becomes acidic as it loses its corrosion inhibitors.

 

i added about 20oz to see if that would settle the issue (help me determine if its a sensor issue or not)....however i havnt driven the car since i added the fluid and im out of town now. so we'll have to wait

the car is 7 years old, so ill probably have it totally flushed soon