the OEM cap is a POS!... around 15k miles, I noticed the stench and spotting of coolant... I checked all the hoses and when I looked at the cap, I noticed the sizzling water and vapor... took it into the stealership, the service manager (who is also a POS!) told me, "the coolant fluid was overfilled..." so I told him, "You're fahking guys did the service, so they must've overfilled it and jacked up my cap! What you going to do to fix it???" When he figured his guys did the fk-up, he replaced the cap and had the manuel laborers spray out my engine compartment, but the spots that were burnt in are still stuck, so it really didn't help anything... I have since purchased a Nismo cap, and boy does that thing ever seat and seal... My advice... if your stealership will not give you a $3 replacement cap, get the Nismo cap or equivalent, it's worth the money to not having to worry...