Spark plugs quality

[crankedup5]

My 550i is due for spark plug replacement, I understand that I should fit iridium tip plugs but see prices vary wildly from £12 - £24 each. Unsure which is sensible and which is just throwing money about? Comments and advise welcomed.

[illmonkey]

OE, always, cost is not relevant!

[ChocolateFrog]

Personally wouldn't use anything other than NGK, still made in Japan IIRC.

The difference between the cheap ste and the good ones is a couple of beers and they last years.

[chrisgtx]

I bought some NGK off eBay and they were misfiring after a short time. I suspect they were very convincing Chinese copies.

[E-bmw]

How many miles have they done?

Iridium plugs basically last forever.

[Huff]

ChocolateFrog said:

Personally wouldn't use anything other than NGK, still made in Japan IIRC.

The difference between the cheap ste and the good ones is a couple of beers and they last years.

That, in any car.

[danb79]

OEM or NGK as stated above; never had any issues with either

[rottenegg]

E-bmw said:

How many miles have they done?

Iridium plugs basically last forever.

Oem ones do, but aftermarket ones don't, such as the NGK Iridiums, as they're only iridium coated on the electrode. The ground strap is plain steel. Oem ones have iridium (or platinum) pads on the ground strap as well.

[Depthhoar]

chrisgtx said:

I bought some NGK off eBay and they were misfiring after a short time. I suspect they were very convincing Chinese copies.

Bought some suspiciously very cheap 'BMW OE' plugs on eBay which I returned to the seller as counterfeits. The resistance of the 8 plugs varied from 7.5k OHMs to 12.5k OHMs. Legit equivalent NGK and BMW plugs should be between 4K and 5K OHMs. Not surprising you experienced a misfire. There were also a few visible manufacturing issues too:


(Above) The knock off plug is on the left, legit NGK BKR6EQUP on the right. Note the difference in colour of the threads between the two plugs, OE plugs should have a faint lilac colour.The electrodes of the copy weren't quite right either. Also, the embossed lettering on the plug was slghtly misaligned.



(Above) The counterfeit plug came in convincing packaging but the crush washer, which could be removed by hand, was another giveaway. Shouldn't be able to remove the crush washer from a legit plug without the help of a cutting tool.

I checked the eBay seller's feedback and he's sold hundreds of these to unsuspecting buyers.

Edited by Depthhoar on Saturday 19th October 14:21

[Richard-D]

They are some convincing copies. I've had some suspicious parts from a local motor factors, one that supplies all the garages near me. It's frustrating because I want to support them but It's so difficult to know whether they've been duped too.

As much as anything I'd like to buy from them because it's more convenient, that and preferring to support local businesses over GSF/ECP etc. There isn't always a convenient local dealership.

[crankedup5]

E-bmw said:

How many miles have they done?

Iridium plugs basically last forever.

Over 50,000 miles, the BMW indy I use advised me at last years service it was time to change plugs next time you are in. I will ask them to fit OEM.

Thank you for all feedback.

[g3org3y]

chrisgtx said:

I bought some NGK off eBay and they were misfiring after a short time. I suspect they were very convincing Chinese copies.

From a rando seller or one of the legit companies (eg PartsinMotion)?

FWIW, NGK for me.

[chrisgtx]

g3org3y said:

chrisgtx said:

I bought some NGK off eBay and they were misfiring after a short time. I suspect they were very convincing Chinese copies.

From a rando seller or one of the legit companies (eg PartsinMotion)?

FWIW, NGK for me.

Random seller. So I suppose I’ve only got myself to blame.
I told them what happened and they refunded me in full.