How long of a drive to Boston is it from northwest Louisiana? I just did a trip to Md (Baltimore area) and back within the last month. What's another 3000 miles on my car? Actually, that would be an excuse to change my oil, huh? And a good way to test out the GC I just installed last week.
So far, my car ('97 Nissan Maxima with 108,000 miles) likes GC. It is quieter than with GTX 5w30, and much, much quieter than with Mobil 1 5w30. It is also smoother, to the point that I want to crank the car while it's idling at a light. I'll be doing a UOA at 3000 miles to check things out.
On a somewhat related note, GC is a 0w30. The US owner's manual calls recommends a 5w30 year round, and a 10w30 for temps above -4*F or so. Someone on Maxima.org posted a pic from a European owner's manual showing their (European) viscosity chart for the SAME car. You can see it here:
http://www.cardomain.com/ride/2146165 If you zoom in to read it, it shows their recommended oils are MUCH thicker. 10w30,10w40, and 10w50 are recommended for temps above -4*F, and so are 15w40 and 15w50! For hot areas (above 14*F), 20w40 and 20w50 are suitable. It also states that "5w30 will positively improve fuel economy". Are the huge differences in recommended oils just because of our CAFE requirements? I seriously doubt Nissan has 2 different specs for their VQ's tolerances, justifying such a wide range of recommended viscosities.
For the gurus, which viscosity would be best for engine longevity? I'm not too concerned with a minor mileage decrease. Temps in Louisiana range from several days of high 20's in winter to 100+ in summer. Trip lengths vary, but are almost always over 5 miles, and about 30% are highway speeds for 35 mile trips each way (over to where bkrell is from). Would a 15w40 suit me better?
Having said all that, and looked at the European viscosity chart, is GC suitable for my car at all when only considering engine protection? Like I said above, my car is running extremely smooth with it, but I'm concerned with protection. I had 2 UOA's show elevated lead when I ran Mobil 1 5w30 2 winters ago, and don't want a repeat. It is also widely recognized on maxima.org that the VQ-30's like heavier oils.
Sorry for the length, but any recommendations would be appreciated. This is also some food for thought (and possibly another thread) if someone would like to start a discussion about US and European viscosity chart differences. Maybe we can get US and European owner's manual viscosity charts for a larger number of cars to compare with each other. This may help us to better understand how US CAFE requirements may be doing our cars more harm than good.
Semper Fi,
Dave