People with model year '14/15, have you guys done this? My car is close to 48k miles and according the maintenance schedule, on the 6th year I am supposed to change the spark plugs and supercharger belt.

Are these items more mileage dependent or time dependent?

 

Judging by your handle I assume you have a V8.
I have a MY2015 V6S, build date Oct 2014, about to hit 60,000 km (around 37.3k miles) so I am coming up to the six year spark plug change point.
I fitted a new SC belt just over three years ago now (larger crank pulley) so I don't need to worry about that for a while yet.
Point is I believe both are much more dependent on miles than age, especially the spark plugs.
I can't see how spark plugs just sitting there are going to wear out or deteriorate and in any event the F-Type Iridium spark plugs are good for at least 100,000 miles before they need replacing.
The SC belt might be a little different in that it might deteriorate a bit with age like most rubber based parts, but I reckon it would be good for at least 10 years unless the car is high mileage and/or thrashed a lot.
I believe that almost all the JLR scheduled part renewal intervals are extremely conservative for two reasons:
1. To make money for the dealerships (check out the brake disc and pad replacement intervals!)
2. To insure against one-in-a-thousand part failures.
The one exception to this is the engine oil and filter change interval of 16,000 miles or 12 months whichever comes first.
That is a sick joke and you should halve that at least for the oil.

 

Mine is V6S with build date early 2014. I am a bit scared to take it on longer trips because I haven't done either service, only did the oil change.

 

Nothing to be scared about at 48k miles, as I said the scheduled intervals for replacing the spark plugs and SC belt are extremely conservative.
Almost zero chance one or more spark plugs will fail at those miles and if the SC belt breaks (very unlikely) then the only problem you would have (assuming the belt doesn't damage anything else) is the SC won't work until you fit a new belt.

 

I would just inspect the belt for signs cracking, tears, and dry rotting, and if none, only change at mileage indicated. And also agree with Oz on the plugs.

 

I replaced the plugs last year (at 6-year service), haven’t worried about belts yet. 57k miles.

 

I have a 2016 with 15K at the moment; I just had my last "free" service and got the print out of what is supposed to be due next year. They are calling it the 72 month service and it includes an oil change which i expected, but they also recommend SC drive belt, Spark Plugs, cabin filter, and alignment. They also like 30 other very important things like inspecting the wiper blades and check coolant level. I plan to do the filters myself, it was just aligned a couple weeks ago, and all the rest they should do anytime the car is there, like check for open recalls/TSBs etc. To me, its really just an issue of changing the SC belt and installing new plugs and whether it is worthwhile to do those both next year when the car will have about 18k and be 5 years old? The other part of that is that they are charging $325 for plugs and a belt plus $1100 in labor. I'm good with using their oil and paying $120 for the oil change, the filters I will do myself, but are plugs and the SC belt really advisable at that point?

 

I wouldnt worry about the plus or belt until you hit the mileage aspect. Inspect the belt for cracks and damage. I havent run across any S/C belts being damaged other than oil/coolant on belt making it soft.

 

I wouldn't worry about spark plugs at less than 60K miles. Unless you have oil burning, regular use of sketchy gas (or other issues that can foul up plugs) plugs last a very long time.

 

Thanks for the feedback - I am all about doing everything to give my rides the best chance at a long life. I use BG products etc. and I will likely change the SC belt and plugs long before the recommended mileage but just not next year. I only drive the car about 2500 miles per year and I am thinking of using my local import specialist for those items when I hit 20-22K- I'm guessing it will likely be about 60% of dealer cost for parts and labor.

 

I have a '14 V8S with right around 20k miles. I'm mostly concerned with the condition of fluids and will change those as recommended in the forum and as seems reasonable. Which doesn't really coincide with MFR recommendations. Hard parts are easier to inspect.

 

My opinion would similarly be spark plugs are more milage based than time.

96000 miles need replacing, six year but significantly less mileage don't bother replacing.

No mention of supercharger belt replacement.
I wouldn't bother unless visual signs of damage.

Service schedule doesn't mention changing supercharger oil, but I would consider doing this.

 

I change my own wiper blades and cabin filter from Rockauto. I know use a private shop for oil changes and he uses the spec oil, about $75 cheaper than dealer. He agrees that plugs are 100k and looked at belt and saw no wear. I'm going let him do brakes, Porterfield, when due. $100 per axel or $180 for both. I have no skills to do it myself. Front pads on our Maser. are $500 after 20% discount at dealer.Car still under warranty.

 

At my yearly service this past Feb the dealer also said at my next service for my '15 R that the SC belt and plugs would need to be changed. Kind of nuts given my car has only 17K miles. Reminds me of my former Ferrari F355 timing belt change which was every 5 years. The belts were usually still pristine, but the issue was the tensioner bearings. I had the tensioners changed to a higher quality part and new owner has gone 7 years now without the belt change. For the belt change, the engine had to be dropped and was close to a $9000 service for belt change + while you in there stuff. Crazy. After getting the Jag, it has been nice to not deal with the huge maintenance costs. I will defer the belt and plugs and change when the mileage is closer to what the service interval says and not by time to not spend $1800 on the unnecessary early service.

 

I would change the coolant at 6 years and forget the plugs until 100K miles.
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I am high on maintenance . After all i make my living from it with Plumbing & Heating . water pump , ancillary and supercharged belt also spark plugs and supercharged oil All changed at 50k miles mark OHH forgot about diff oil and transmission service as well. , brake and coolant fluids changed every 2 years . but I am a True enthusiast , beware of imitations