A 8

Time to change on mine in a few months and I've started to research which plugs will be best. I know I should post this in the D4 forum but the lifecycle of the D4 is not yet where this level of detail and experience seems to be available (so trying to gather whatever other experience is out there). On my old 4.2 D2 I first changed to NGK but was not at all happy with how the car felt, it was not as smooth so put in Bosch platinum which was the same as the original ones if I remember correctly.
When I try to find something for the D4 The Denso IRIDIUM TOUGH VKB20 comes up most everywhere however I have never heard of them, anyone else? They are supposed to give better performance and last longer, not that I care much about lasting longer but better performance is nice.
Can't find a Bosch alternative, there are NGK. Also, is there any reason to change the coils as well?
Thoughts anyone?

Mister Bally

Whatever the OEM plugs are in the engine are the best. The engineers who designed the engine and tested it with different plugs specified the best ones available. Remove one to confirm what is installed in case any documentation lists more than one.

You can't go wrong buying them from a dealer. Even if they are $3-4 more than some online place; you know you are getting real, non-counterfeit parts especially since the come in a VW/Audi box and have the logo in the ceramic or steel on the plug. My old non-fsi listed both NGK and Bosch in the book. Pulled one out and it was Bosch so that is what I have been using ever since.

MP4.2+6.0

Audi OES are almost invariably NGK or Bosch. For the W12 (at least in USA) it is only NGK though there is a listing for Bosch. Depending on which Audi I have had when they still had the original plugs in them, they have always been one or the other when I pulled one to check.

Denso are fine, but neither NGK nor Bosch are somehow laggards on technology, assuming OE spec. fitment/number and not just generic.

mishar

I would just add that one can't feel any difference between different spark plugs dedicated for a vehicle while they are new. Saying that you can't gain any performance by any spark plugs. Use best of the line NGK and be happy.

A 8

Thanks for your responses, seems I need to pull one before ordering or just get them from the AUDI dealer.

volvopentaman

I will too recommend OEM plugs.

Second best option is to find the exact same plugs as bosch or NGK. As non-oem i prefer NGK plugs, they've never let me down.

I've ran 6 sets of OEM plugs through my Volvo S90 -98 in 9 years and 200tkm without a single problem, so I know exactly what I talk about.

I've had numerous problems with cheap plugs that don't work as intended with the engine.

It's not worth saving 50$ on buying plugs that might work, when you can be 100% sure By buying OEM stuff.

I've bougt Bosch, Denso and NGK plugs for Volvo "whiteblock" engines (Inline 4,5 and 6 cylinders), and have had a few problems with rough idle or performance in some cases, especially with naturally aspirated variants. All NON-oem sellers sell one or two-tip plugs as default, when the OEM plug is ALWAYS 3-tip for NA engines (turbos have iridium 1 tip). This is why i recommend to stay away.

The best joke was, when i thougt about buying NGK NON-oem plugs from an indy dealer, they were one-tip, they cost more than the set of 6 plugs in OEM packaging from volvo!!! NGK plugs were 6,9€ ea = 41,4€, volvo plugs 37€ set!

Filters and liquids are stuff you can play with, you can buy exactly same 5W30 longlife2 504/507.00 spec'd oil in 20L canister from germany for 150€, when the dealer charges 5 times more.

Filters are only MANN and Bosch manufactured for these cars, so you can't go wrong By buying non-oem, as they only lack the audi-logo, and are 100% same stuff as OEM.