As much as I have heard good reps for V12 engine I must admit I have heard some bad reps on it . So, mileage is pretty low but that still doesn't mean the engine should be perfect .
For 5.3 liter engine some infamous leaks are known but don't know about the X300's V12 . However there is something that bugs my mind is that why Jaguar havestopped making anymore V12s since 98 . [&:]
It should be a more reliable engine to bimmers though

 

Reliable car, but I wouldn't really want for it to be a daily driver. The only problem with the V12 that jumps to mind is keeping the engine cool. I would do anything possible to upgrade the cooling system. Keep an eye on that coolant level, and I would make sure that the fans are working properly. First thing I'd do though is put a new water pump and thermostat. A cool V12 is a reliable and strong V12.

 

The 1995 had a 6.0 liter v12. Just FYI. Biggie is correct, keep the engine cool. Jaguar updated the gaskets, so most of the oil leaks went away. I would look at the type of driving you do to make a decision. v12 cars are not for stop and go traffic. If you spend a great deal of time on the open road, it would be a premier vehicle. If you (like most of us) spend most of your drive time in bumper to bumper traffic, flipping off the moron on the cell phone trying to cut into your lane; it's probably not the best. v12's like to stretch their legs. They also prefer to be driven often. Don't buy and put in the garage for the occassional cruise either.

 

Earlier W140 MB 600 SEL models are prone to failures and expensive repair bills . What's said late models from '96 and up for the W140 S600s are quite reliable (no more harness problem ) .
I just remember for what a car mag commented about the engine for the Double Six aka XJ12 :"The engine is very powerful so to drive in short trips" .
I asked about the fuel consumption and for urban driving you get almost equal to Vortec engine (6.0 V8 ) [&:]lol.A german mag gave average consumption as 18lt/100 km for the Double Six[:-]

 

Not that it's built deficient at all, it's just that most engines can handle a waterpump failure or a radiator cracking and over heating a couple of times. The V12 not so much. I wouldn't want it as a daily not due to reliability, but instead because of the gas consumption and the grind of stop and go traffic that I personally deal with. If you want to drive it every day, but it's mainly straight traffic...go for it. I don't know about it wanting to stretch it's legs like Ken says, but he would know WAY more than I would. I don't see the harm in only driving it twice a week or so. That's just me.

 

xj12 is a beautiful car.. just keeper cool. something like 6 cat's on it.. fuel mileage isn't good but man it's a beautiful car..

 

We had 2 750 BMW V12s and an 850 BMW, Mercedes S600 etc All new were great cars although id never buy a used one unless it had low miles and very well maintained. They were very expensive to service( free maint wasnt included back then), never touched the Jag. Although I also wonder why jag doesnt offer a top range V12 in at least the XJ if not the XKs also.

 

They no longer offer it because it proves less problematic and more efficient to simply add a supercharger to their already fabricated V8 and make more power that way while being more cost effective.

 

If your only concern is cooling, I'm sure there are any number of aftermarket cooling fans one could add to suit. However the V12 has had some issues and any repair would be expensive as with any exotic.

You may want tolook at alternate powerplants, such as the old reliable 4.0 six, or the v8.

As to estimating reliability, each car is different and while one model in a type might run perfectly forever,the next one down the line might be nothing but bad news. It's luck of the draw my friend. Jaguars as a whole are somewhat maligned, but most of them are excellent cars if given proper care. The X300 is as are most Jaguars post 1990 reliable and solid. But again it really depends on the particular car... and your commitment to care. You will find owning a cat a unique and hopefully deeply satisfying experience. I know I have...

 

absolutely not reliable to use in the long run, maintenance and repairs are often and expensive.

 

Let’s be honest here. Why are V12’s so hard? The truth is they aren’t. Is a V8 twice as hard to figure out as a 4 cylinder?
No because V8’s are common and if a sensor fails it’s one sensor. Sure there are 8 spark plugs but those last 100,000 miles now days and replacing 8 doesn’t take twice as long as four because you already have the tools out. You don’t have to drag them out again for the second 4. The same policy applies for V12’s
The truth is V12’s imply exclusivity. So a premium must be charged. Mechanics are human. They need to pay bills so getting a little extra from the guy with something exclusive just is normal. I’ve seen perfectly good V12’s totally rebuilt because a vacuum hose developed a leak, the distributor wasn’t properly maintained. $5-7000 charged for a $3 hose or three drops of oil.
Oh it would be rebuilt and cleaned up etc. pictures taken it it coming apart and going back together. Ordinary wear shown as the “fault” good thing we caught this-
The Transmission in them is similar to the transmissions in millions of GM cars that are known for reliability. If you put a little piece of plastic upside down the transmission will delay or hesitate. Bring it back, drop the pan, put it in right and it’s fixed.
But after a expensive engine rebuild, expecting the cost of a transmission rebuild was simply too much. Here take it he said and didn’t want to hear anymore.
Knowledge is power.

 

http://www.jagrepair.com/images/TSB/...Engagement.pdf

The question is if this issue shows up and is acceptable

And how involved do you want to get to swap out to a orange dot later version GM 4L80 - E transmission

Notice the VIN # and is this really the range of effected vehicles

 

Why is this post in the XJ6 forum instead of the X305???

 

If you want a beautiful car that looks like the XJ12 get 4.0 XJ6L or a Vanden Plas 4.0 model. They have a good record for reliability. ( Well you could get a V8 version also) The Vanden Plas are usually long wheel base cars, The Vanden Plas does have nicer wood veneer, higher spec interior with tray tables, different upholstery and rear seat arrangements. I have a '97 XJ6L that I find to be beautiful enough. The long wheelbase X300 variants are all quite rare. The extra wheelbase makes for a very spacious rear seat, noticeably roomier than the standard version. It looks quite impressive to your rear seat passengers. Of course you will probably never ride back there, I haven't. The V12s are legendary. That's why I bought one. Jaguar had the most successful passenger car V12 engine of all time. Well over 150,000 built, mostly in the XJS. Emissions and fuel economy requirements are what killed that engine. Although the H.E. and 6.0 versions were pretty good. Of course the new V8 (starting in 1998) could pretty much match the performance of the V12 at lower cost and complexity. That XJ12 is a real classic but maintaining it properly can be a challenge.

 

Considering the thread was started 12 years ago, I suspect the OP made a decision a long time ago. We have a new member who seems to specialize in tomb raiding to bring long dead threads to life again.

 

Would that be Lara Croft?