Spark Plugs

[Redline]

It seems that many recommend NGK Iridium spark plugs, but, they are considerably more expensive than Bosch - by the tune of £30 or even more expensive a set, even using the cheapest prices from uk based reputable web-stores. That's a great bit of money to spend just for a tiny bit of metal that is less electrically conductive than platinum or copper cores. That's getting towards a whole tank full of smile juice!

Spark plugs have up to 40,000V or more discharging across them, so, I don't see many metals surviving too long without being eroded.

On the basis that they are supposed to be longer lasting, is it worth paying the extra, or, is more frequent inspections and changes with cheaper parts the better way to go?
Is IRIDIUM it just a way of getting more money without any real long term quantifiable advantage?

What is the received wisdom on spark plugs?

 

[Sean d]

I just can't bring myself to pay NGK prices and use bosche, being old school I just use plugs for 6-7000 miles so I just change them more regularly.

 

[Redline]

That's the conclusion I was coming to as well Sean.

We're never likely to leave the plugs in long enough to get the benefit of their longevity.
A better performing cheaper plug seems the best option.
Am looking at the Bosch Double Platinum - Platinum core and a V in the ground conductor that presents two edges for the spark to land on without the heat sink and flame quelling that 4 ground conductor plugs have. Less than half the price.

 

[t-tony]

It is more than likely most of us could fit a set of new spark plugs, without going the Iridium route, and never need to change them again. Some platinum tipped plugs don't get looked at, let alone changed, until they've covered 70,000 miles.

Tony.

 

[Redline]

It is more than likely most of us could fit a set of new spark plugs, without going the Iridium route, and never need to change them again. Some platinum tipped plugs don't get looked at, let alone changed, until they've covered 70,000 miles.

Tony.

I'm rapidly heading towards that mileage Tony

Back in the day checking the plugs regularly. It tells you a great deal bout your engine. The electronics do all of that now.

 

[t-tony]

I'm rapidly heading towards that mileage Tony

The point I was making Ian, is will you do another 70K in that car? You're absolutely right in your comment about engine management too, modern engine electronics keep an engine in tune many times better than even the best mechanic ever, ever could. Plugs last much longer, engines carbon up less etc.etc.

Tony.

ps. We usually fit NGK plugs at work and I cannot remember the last time we had to change a defective one, we change them routinely on regular customer's cars who have a "full" service each year and we throw away spark plugs which have not even done half their work. Seems a waste to me.

 

[Mint]

I ran my last set for 29,638 miles. I did not notice any difference with the new ones only a gap in my wallet. The old ones looked fine as well.

 

[Redline]

The point I was making Ian, is will you do another 70K in that car? You're absolutely right in your comment about engine management too, modern engine electronics keep an engine in tune many times better than even the best mechanic ever, ever could. Plugs last much longer, engines carbon up less etc.etc.

Tony.

ps. We usually fit NGK plugs at work and I cannot remember the last time we had to change a defective one, we change them routinely on regular customer's cars who have a "full" service each year and we throw away spark plugs which have not even done half their work. Seems a waste to me.

A bit of margin on new plugs as well as charging for the time to replace them, needed or not.

Must be a market for part used plugs

The ones in at the moment are NGK but they don't have a model number - only "BMW" on them, so, while they work fine, who knows if they are the correct ones. I guess some engines have different height for the central core etc.
The gap is 0.7mm but I cannot find anywhere that says what they should be.

 

[t-tony]

I'll check on Autodata tomorrow Ian.

Tony.

 

[t-tony]

A bit of margin on new plugs as well as charging for the time to replace them, needed or not.

That is the result of so called "menu servicing" people are quoted a set price depending on engine cc. it makes someone's life simpler.

Tony.

 

[Mazza]

I get a third off on the cost of any plugs for mine..

But thats because I’ve only got 4 cylinders whereas you all have 6

 

[t-tony]

Are you an enlisted member of the T**t!! club yet ?

Tony.

 

[Mazza]

I applied but rejected as too stupid!

 

[t-tony]

Not any more mate.

Tony.

 

[Ianmc]

I get a third off on the cost of any plugs for mine..

But thats because I’ve only got 4 cylinders whereas you all have 6

And use less oil and petrol, cheaper to buy. M44 is best kept secret , ever!

 

[Redline]

And use less oil and petrol, cheaper to buy. M44 is best kept secret , ever!

Ah. Good point, well made.

But, to counter that, we don’t have to spend lots of time and money on replacing rusty bits and perished rubber
It’s well worth it feeding those horses

 

[Ianmc]

Ah. Good point, well made.

But, to counter that, we don’t have to spend lots of time and money on replacing rusty bits and perished rubber
It’s well worth it feeding those horses

Good to know that 6 cylinder cars don't rust

 

[Mazza]

Good to know that 6 cylinder cars don't rust

That’s because of all the oil leaking out of the 6 cylinders due to the added pressure of all those horses

 

[Stevo7682]

Ian Lynne's zed uses Bosch twin electrode plugs.
But my Dakar uses Iridium plugs with a 60k change when I got my zed still had original plugs in at 84k
Cost me £62 for the 4 plugs but they will stay in 60k .
If you spend the extra money on the Iridium plugs they are long life so will last an extended period of time over standard plugs

 

[t-tony]

Exactly what I said Steve but not many of us will do 60K in our cars.

Tony.