I have noticed that after three months of heavy city driving my coolant level has gone from the top line to the middle. About 100ml. This seems normal to me. My other cars a VW Golf and a Toyota Sequoia both use up some coolant. Just wondering how often you have to top up your coolant.

 

the simple answer should be "never"

my 30,000 mile 2009 XF started using coolant, it turned out that the thermostat tower was cracked and leaking.

if you are needing to add coolant on any sort of "regular basis" you probably have something that needs attention.

needing to add some coolant every 20,000 miles is reasonable, but not every 100 miles

EDIT: I just noticed you said from the "top to the middle" I'm not too familiar with the XF but on my XJR you can spend your lifetime topping up the coolant to full but it will always somehow end up right in the middle. don't worry about keeping it full to the top, just monitor it if it goes below the middle and if you get a warning light on the dash

 

Depends on the coolant system and wether it has a overflow or not or if totally sealed. Totally sealed will not drop, overflow system will because when it heats up it discharges expanded fluid to overflow tank that its free to evaporate from. Then gets drawn back eventually it will return air instead of coolant and theres your drop
the xf is sealed except everytime you check it

 

No modern car uses an open cooling system. European cars use a full pressure system with an expansion tank. You MUST NOT overfill such systems. the air space is carefully calculated to compress as temperature and pressure rise and expand as they fall, maintaining cooling system pressure. There is a blow off release to ensure the system cannot overpressure. If the coolant was overfilled then the over pressure valve will blow out coolant when hot until the airspace is the correct size. There is a vacuum release to ensure the system does not collapse a hose if it is leaking coolant somewhere.

If the coolant level remains between MAX and MIN then no fault exists. If coolant is still disappearing below MIN after reaching this level you have a fault which must be repaired or you could lose your engine.

I note that north Americans and Japanese cars still use the antiquated external coolant bottle and radiator tank cap which accommodates movement of coolant from the full radiator during temperature variations. These also must not be over or under filled at the external bottle.

Modern cooling systems should not be routinely checked for level. That cap stays on.

Jaguar is unusual in using an opaque expansion tank. Most cars have a translucent tank which is checked for level by eye. Maybe jaguar is supremely confident in its warning light system!

 

My '99 S-Type is about the same. I'm running 50/50 OAT/water. Normal, I'd say - you'll always lose some small amount to evaporation, I think.

 

and Jagular this is why I said open and closed. just because we're in a XF forum doesnt meen others with other cars dont read. The older XK's J's etc are not totally closed. their expansion tank gets filled to the top cold. When it heats its goes into the open overflow tank which is vented to atmoshere and subject to evaporation. Its not a totally closed system

 

I meant to stress you don't remove the "rad cap" anymore. For expansion tank systems the coolant has nowhere to go unless there is a defect causing a leak. For the other systems the overflow bottle should be translucent. No need to take off that rad cap either way.

Evaporation from an overflow bottle would be very slow. I've never had to top up such a system in all the years I owned Japanese cars. I won't buy "domestic" because they use generally antiquated engineering. The new Dodge Dart II looks pretty exciting....but then it is an Alfa Romeo in disguise!

 

Hey Brutal, you seem to be the man with the last word being a Cert Tech.
Do XF loose some coolant do to the "semi vented" as you state?