I just purchased a 2004 S60R AWD, so researching the parts stores looking for the correct spark plugs, 2 different thread reaches are advertised for the 2.5t. The ones in the car were 19mm but I see 26.5mm are also advertised as correct. Volvo dealer here is not much help. Where can I find the correct tech reach for this model?
Bought with less than 100K miles, great shape,it runs pretty good now but want the right ones. Not really wanting Volvo plugs ...

 

I would recommend the Volvo ones.

 

I believe that the thread depth has to do with turbo vs non-turbo. ?
And I must also recommend ONLY using genuine Volvo plugs.