I purchased a 2003 X-Type in August. I had to take it to the dealership for a new key and a tire store for new tires in the same week. Somehow between the two of them one of the nipples on my overflow bottle got cracked off and I have a serious fluid leak problem. The dealer wanted $189 for the bottle and $450 to put it on. I ordered the bottle online for $88 and it doesn't look too difficult to install. However, the dealership told me I have to use specialized Jaguar antifreeze because, "Anything else will turn into glue and ruin your engine". I've looked around, but can't find a definitive answer so the question is, what type of coolant I can use. Do I have to pay $16 per liter for Jag coolant or can I use the standard orange Dex-Cool?

 

There should be a sticker/label near the expansion tank with the coolant spec listed - I believe 03+ vehicle spec calls for Dex Cool - to be 100% sure make sure the coolant spec listed is mentioned on the dex cool as "meeting" or "exceeding requirement.

 

Who ever told you that bull about using only Jaguar coolant is bull s****ing you. I've been using Prestone 50/50 with Dex Cool in my 2003 since buying it in 2007. I run it for roughly 5 years just changed it in July. I get it at Walmart for about $12 a gallon. That's just the dealers trying to scare people into buying their ridiculosly over priced coolant.
You were right not to fall for the dealers price and labor cost for the expansion tank either. I got one online last year also and it takes maybe 30 minutes total to remove the old and install new and drain and refill with new coolant. So I can't for the life of me see where they would ever have the guts to quote $450 for the labor.