Bosch Platinum 6730 Plugs for S60 2.5T

estrekal · Post by **estrekal** » 14 Oct 2019, 10:35

Hi everyone,
I know the spark plug debate/discussion is a topic that's been beat to death regarding these cars, but I did just want to get a second (third, fourth, or even fifth) opinion on these plugs.

I received some Bosch 6730 platinum plugs in the mail the other day and set to replacing them Saturday afternoon. I noticed immediately pulling the old Bosch platinums out that the thread count on the new plugs was significantly smaller.

Anyway, I replaced all five and fired the car up. It seems to be running, idling, and accelerating just fine, but I am concerned that perhaps these aren't the right plugs. I don't want to have any problems down the road (no pun intended). On several parts sites that I looked at, I see that this are listed as being not compatible with my vehicle. A few other places say that they are, so I am confused.

Any insights or advice would be much appreciated! Thanks as always! My car is a 2004 S60 AWD with the 2.5T.

estrekal · Post by **estrekal** » 14 Oct 2019, 10:41

I guess I'm wondering if I should pull these plugs and replace them with something else. As far as I can tell, there doesn't seem to be a lot of information out there about these plugs for this specific application.

Post by **June** » 14 Oct 2019, 10:50

You knowingly put plugs with different threads into a soft aluminum head? I would worry more about the now damaged threads in the head. If it is running fine and you are blessed that one or more does not blow out, I would never, ever, ever remove them again. June

estrekal · Post by **estrekal** » 14 Oct 2019, 10:55

June wrote: ↑14 Oct 2019, 10:50 You knowingly put plugs with different threads into a soft aluminum head? I would worry more about the now damaged threads in the head. If it is running fine and you are blessed that one or more does not blow out, I would never, ever, ever remove them again. June

Thanks, June for the response. If this is indeed the case, that's going to be a real bummer.

I wonder if it's actually a different thread pattern, or if there are just fewer threads? I guess inevitably fewer threads would indicate a different thread pattern...

I thought that I read somewhere else that these were the current iteration of the Bosch platinum plugs--but I could be wrong

.

-Edan

https://www.ebay.com/itm/5-X-Spark-Plug ... %7Ciid%3A1

Post by **June** » 14 Oct 2019, 11:24

estrekal wrote: ↑14 Oct 2019, 10:55
June wrote: ↑14 Oct 2019, 10:50 You knowingly put plugs with different threads into a soft aluminum head? I would worry more about the now damaged threads in the head. If it is running fine and you are blessed that one or more does not blow out, I would never, ever, ever remove them again. June
Thanks, June for the response. If this is indeed the case, that's going to be a real bummer.

I wonder if it's actually a different thread pattern, or if there are just fewer threads? I guess inevitably fewer threads would indicate a different thread pattern...

I thought that I read somewhere else that these were the current iteration of the Bosch platinum plugs--but I could be wrong .

-Edan

Let's say the the Genuine Volvo plugs have 10 threads per inch and the Aftermarket Bosch you installed had 12 threads per inch, your head had 10 per inch. Now the new 12 per inch aftermarket plugs have cross threaded some of those threads in the head. So any correct aftermarket plug would have the same thread pattern as the original, that would never change. So either the aftermarket plugs you pulled or the ones you installed are incorrect, but both have been installed in that head. Therefore the threads are damaged in any event.

Hopefully the current set is the incorrect, and they stay in place. As likely they will run fine for 100K or more with platinum. Really will you have this car for more miles than that? Deal with it when either plugs blow or they get so worn they misfire. With luck neither will happen during your ownership. June

estrekal · Post by **estrekal** » 14 Oct 2019, 11:30

I've had the car for about three years now, it's at roughly 123K miles now. This is the third set of Bosch platinum plugs that I've used now since I've owned it. I can't recall if there was a difference between the first and second set, but I did notice it immediately this time.

Well, I certainly appreciate your input, and I've got my fingers crossed and I'll cross that bridge when I get there. I know everyone says that genuine Volvo plugs are the way to go, but I've always had good luck with Bosch in my older Audis, Saabs, and Volvos. Shoot, I even had excellent luck with Champion plugs in my old V70 (that's what the manual suggested).

MRScott · Post by **MRScott** » 14 Oct 2019, 12:10

It was stated there was a "thread count" difference, as in not as many. This says nothing concerning the TPI or threads per inch. He states there is less thread not a change in pitch. So ruining the head comment is not applicable. Ideally the threads should not enter the combustion camber to an extent that they become covered in deposits from the combustion process. Coated threads can be difficult to remove when they come out. The installer needs to be aware that the right thread depth is maintained with the correct plug. Commonly referred to as "reach".

Post by **June** » 14 Oct 2019, 13:01

MRScott wrote: ↑14 Oct 2019, 12:10 It was stated there was a "thread count" difference, as in not as many. This says nothing concerning the TPI or threads per inch. He states there is less thread not a change in pitch. So ruining the head comment is not applicable. Ideally the threads should not enter the combustion camber to an extent that they become covered in deposits from the combustion process. Coated threads can be difficult to remove when they come out. The installer needs to be aware that the right thread depth is maintained with the correct plug. Commonly referred to as "reach".

The OP stated the thread count was smaller, not the plug was shorter. So to me I understood that to be reference to threads per inch.

If it is just a shorter plug not a reference to threads per inch, than he just installed cooler plugs correct? June

estrekal · Post by **estrekal** » 14 Oct 2019, 14:21

I should maybe re-phrase what I observed. The threaded area on the plug that I removed was longer (and therefore I'd guess has more threads) than the one I put in. I'm not sure if the overall length of the plug differed or not--I didn't bother to look at the two side-by-side.

Post by **abscate** » 14 Oct 2019, 14:25

The critical thing is the thread per inch or mm per thread count - that has to be the same for the plugs and the head. If you can, you can put the threads into each other and see if they mesh - if they do, you are ok.

Of course, if you have cross threaded the wrong pitch plug in, don't remove it until you are near a shop.