I have a 09 xf SC with 75,000 miles. When do people usually change plugs?
Is it a diy job?
Thanks.

 

I believe the interval is 100,000 miles.

 

I just did mine at 82k on the 5.0L supercharged. They are rated for 100k, but I wanted to do it now for peace of mind.

 

With the proper tools and time it is a DIY job,
https://www.jaguarforums.com/forum/x...change-145292/
but not a job for the faint of heart. Like everything else the manual gives you a long run time on the plugs, But I'd say the max run time on them is 50 to 70k mi. The Champions I used gave 7 yrs and unlimited mi.

 

Earlier engines like the 4.2, both SC and NA were scheduled at 100K miles. This proved over the years to be a conservative interval by a considerable margin.

What makes you say the same interval is excessive for the 5.0?

 

I changed mine at 85k in my 5.0 and they looked in great condition. I guess I did it because I fancied the challenge and I never liked the idea of plugs becoming too seized (though obviously mine weren't).

It was a complete pain to do though, I seem to remember I found the rubber covers that go over the coilpacks to be particularly difficult to remove, even with a heat gun, and the coil pack/injector wiring, where these fiddly little plugs had to be removed one at a time in order to get enough slack in the loom to move it out the way. Access at the sides is very poor.

This was the setup I used for the actual spark plugs (with a BMW thin-wall socket) - If I remember correctly I put the socket with the shorter extension bar and the u-joint in first and angled it so the u-joint socket poked directly upwards, then once that was located on the spark plug properly, slot the long extension bar in and remove. The hardest part of the job by far was getting everything off so the plugs could be removed though.

 

Just peace of mind.

A lot of mfg rate things as "lifetime" and whatnot, but have been proven to be false (much like the transmission oil in these cars, Jag says lifetime, ZF says 60k)

I would rather be safe than sorry. Now I don't have to worry about any major service for the next 70k miles or so. If I even keep the car that long.

 

Thanks but I was curious about another poster who quoted 50K. I agree that if there's no information that supports an interval that appears to be 'cavalier' then some caution can be applied, but the 100K interval for plugs has been around for decades across many car brands.

For fun, a buddy ran a set till they started actually misfiring. That was at the 400K threshold.

 

My experience with plugs has been you don't feel how bad old plugs are until you put new ones in..lol That said, the 100k mi interval is a requirement to meet emissions (80k mi) here in the US.
I generally cut everything maintenance wise in half, or stick to the severe service schedule. If you look at what happens to other maintenance items running to manufacturers recommendations -
Oil 10k mi, but the wear and viscosity packages are all gone by then and it's carrying a lot of dirt, fuel and water.
Coolant 5 yrs, but it gets very acidic by then.
Trans oil lifetime, but is fairly done with a synthetic blend (As ZF fluid is) by 50k mi.
Remember, car manufacturers have a vested interest in letting you run high mi maintenance schedules (From 0-50k mi) that let your car run fine until the warranty is gone at 50k mi? Yep you followed the suggested maintenance schedule, but the damage is done, and your warranty is over, hope them pockets are deep $$$$.

 

Thanks for all the replies. Sounds like I will change the plugs, as much as I'd like to do it myself, itsy daily driver, so can't have it down for days. Probably will pay to have it done.
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