Just had my 1st oil change at 1300 miles. I noticed that it now takes a bit longer for oil pressure to normalize after startup and under similar load, the oil pressure seems to be higher. I know the dealer uses Castrol 10W30 for oil change. the question is, when the car was built in Japan, did they use 5W30?

 

I don't know for a fact but I believe that they factory fill with 5w30 since that is what they want everyone to use and that is probably what they did their EPA certification with. Slightly higher pressure at startup would be expected with 10w30 due to higher viscousity cold. Why did they use 10w30? Not that it matters with summer here.

 

I wondered the same thing. I'm pretty sure it came with 5w30, but the first oil and second oil change my dealer(I got like 4 free oil changes) put Castrol 10w30. It doesn't really matter here since it is like 80 when I start my car in the morning and 96+ when I come home from work. I plan on changing to Mobil 1 synthetic 5w30 at 10,000 miles.