$15 spark plugs ?
 

Can anyone tell me why the spark plugs for my 1976 911s are

999-170-017-90-M14
Bosch W-5-DPO Spark Plug (6 per car, sold individually), 911S (1974-77)
Brand: Bosch [More Info]


$15.00

But these which would also seem to be appropriate

999-170-165-90-M14
Bosch WR-5-DC+ Spark Plug, 911 (1969-77), 911SC (1980-83) [More Info]


$2.75

Does anyone know the difference or have a good reason to buy these.
Regards michael

Watch out for Bosch plugs for older cars.....most are made in S America and the quality sucks just like the dead on arrival Bosch Coils....try NKG's.

+1 on crap from S. America.

I got a new Bosch coil for my 74 BMW Motorcycle. DOA. It got so hot it burned my hand.

Right now, Bosch is 2nd in my "hated replacement parts", right behind URO.

Which NGK plug for a 1976 2.7 911S ?

Ngkbp7.

Thanks Gary

+1 on using NGK plugs in EVERYTHING I own...have for years, no regrets. When I went to replace some Bosch's for some lawn equipment at the local NAPA, some of the NGKs were around 2 bucks, others (R types) were more than double but I needed them for those chainsaws NOW. Got home later and looked online....took both boxes of 10 back, caused I was PO'd at the markup ripoff on the R-types. All NGKs should be in the 2$ range...if not, keep shopping :). I bought mine online (free shipping), and got my next set for the 911 essentially free when all was said and done (with the savings)...

Update to Spark Plug Question
 

Hi all,

New to Porsche 911 ownership and repair; my plugs are solid, checked them when I was adjusting valves and all were perfect, but according to service records they were most recently replaced in 1998. So, just in case, I want to replace them and keep a few spares in the car.

The Bosch plugs I found in the car had "WR 5DC + Russia 311 +15" written on them, so not made in South America like the problematic coils. Replacing with like appears to be a costly endeavor at $11/ea on Amazon, and there's a gazillion different options according to a cross reference website:

https://www.sparkplug-crossreference.com/convert/BOSCH_PN/WR5DC

Thoughts? Waiting for a new rotor, so I have some time before I plan on replacing (and the $20 off $250 from Pelican is absolutely BURNING a hole in my pocket, LOL).

Thanks!