what is the best oil for engine longevity and performance for climate 35-75F year round and moderate driving habits?

 

Any name brand oil with the proper API certifications should be good. Chevron oil is normally under $1 a quart at Wal-Mart or Target. It's always best to follow the manual. 5w30 or 10w30 should suffice for you. If it never gets too cold, choose 10w30. The narrower the range of the oil, the better, as it takes additives to give it the wide temperature range. Oil doesn't really wear out, rather, the additives do.

Personally, I use Mobil 1 Synthetic 15w50 (sometimes I get it on sale at $3.98 a quart, sometimes it's like $4.78 a quart) and factory Nissan filters. I used to change every 3000miles, but have changed to every 5000 miles since I drive a lot of freeway and put on about 3000 miles a month.

There's no doubt that synthetic oil is superior to regular dino(saur) oil in measured tests. However, with regular oil changes, the synthetic may be just an extra cost and be too good, i.e. when you're car's running within spec and with regular changes, you're not taking advantage of it's goodness and increased cost, so it's up to you which you choose to use.

Part of the reason you want to change your oil depending on driving habits is to renew the additives. Another is that lots of short trips tends to cause the engine to heat up and cood down a lot. This condensation can dilute the oil, whereas lots of freeway mileage means the engine reaches operating temperature and stays there. Parts tolerance is another. When the engine is cold, parts contract, and blowby through parts such as the rings can contaminate the oil. Another is to drain any suspended particulates like metal shavings in the oil.

Hope that helps.

-V

 

Here's one of the sticky threads with some more info
http://forums.maxima.org/showthread.php?threadid=36551

 

I use mobil 1 10w30 fully synthetic, and mobil 1 filters. I think that the car just plain runs better with the sythetic oil. My oil runs very cool, never above 150, even when I drive it hard.

 

I currently use regular 5W30 oil. For the first 3-4 weeks after I change the oil, it definitely feels as though the car runs smoother, revs faster, and just plain kicks ***. From all the talk from syth oil users, it seems that these properties last a whole lot longer...

 

it's the Synthetic oil or just in my head but the car feels happier, revs easier and has smoother running quality when I use Synthetic. May be just me, but it sure feels good to blow the extra money on the best.