I am trying to buy new spark plugs here, but they donīt have the
original ones (bosch FR5 DTC) so they offer me the Bosch FR56 that has
4 electrodes instead of 3.
Has anyone tried this FR56? are they usable in our cars

thanks in advance for your help

 

That's what I put in after the rebuild. They are working fine.

 

Thanks sundog, I am going to buy them even if my mechanic is not very happy with the change

 

After recent "research" on Bosch spark plugs for the 964, I have found that what Bosch recommends in Europe (and Australia, etc.) is different from what they recommend in the US. Their US web site suggests only ONE plug, which is part number 7403, and which their parts catalog lists as a plug numbered FR5DTC. From what I understand, this three pronged electrode design is the original application plug for the 964 from the outset.

Now, consulting the current Bosch website in Europe (English version, of course), one finds that Bosch recommends a new plug type called "Super 4". Oddly, the "Super 4" model does not appear in the US market according to their US website. The specific plug number for the Super 4 in the Europe catalog is "512", and in some other Bosch material it is cross-referenced as "FR56". From reviewing the Bosch material you can clearly see that the Super 4 is a four pronged plug and that Bosch also promotes the plug as offering a two heat range capability.

Checking with US suppliers, I found that FVD in Florida could supply the Super 4 plug and I have placed an order with them. I have not yet installed the plugs. My local Porsche dealer, when advised of my research, speculates that the difference in 964 plug selection between the US and elsewhere is owing to differences in gasoline quality. That may well be the case, but I speculate that there are some marketing issues at work as well.

 

Blu thanks a lot, your answer was very informative, the same happens here I guess, they offered me the FR56 (4 electrodes) as a replacement for the FR5 DTC (3 electrodes)
I am certain that no damage to the engine could be done with this new plugs

 

any other user of Bosch FR 56????