Frank D,
I have the same car('04 w/ 2.5), and I'am very curious. What do you mean when you say that your car loves the Castrol 10W40? Im currently using Havoline 10W30(summer time) and mine seem to be OK as well! Mine is smooth and quiet and fuel economy seems normal. In the colder months, I have used 50/50 of 5W20/5W30 for upstate NY winters and notice no changes. Has the Castrol 10W40 made your engine seem smoother and quieter with better than normal MPG than other oils that you have been using? Im really curious because I've read so little about these engines with the exception of..."Nissan engines like thicker weight oils". Maybe you can shine some light on this subject.
quote: Originally posted by ekpolk: This makes me wonder why Nissan valvetrains showed this tendency. And of course, it's more than idle curiosity in my case.
Well..I haven't checked but I would imagine the VQ valvetrain is quite different than the KA24E so it may not apply the the newer designs. And since I never worked with any of the Nissan engineers, I'm purely speculating on their motivations. Like I mentioned before, I'm guessing that they may simply be waiting until all their engines have been val/ver'd with the newer fomrmulations.