This is VERY interesting information for me regarding the MK4.

Quoting CCFJ1: "It will depend on the laser in the mk4 mate, some repairs are done with the white cap laser and this will only read cd's, black caps will read dvd and cd's

If you have the black cap, then its advisable to use the cd for OS, personally, I would not use a dvd for OS unless I absolutely had no choice."

Hmmmmmm, some MK4s may have white cap laser type installed?? I thought that all MK4s had black cap laser.

I don't know yet but if my MK4 has a white cap laser installed today, is it still possible for me installing the black one?? (I have already ordered a black cap but haven't received it yet). This one: Grandata Online

/Mats