Viscosity recomendations for Nissan VQ4.0L. Opinions wanted.

[Dude-Man]

Hello!
Have a newer Xterra with the 4.0L VQ engine. I've been hearing that the VQ's prefer a little thicker oil. Manual states the now common 5w-30 but also lists either 10W-30 or 10W-40 for temps over 0deg.
Well, I generlly prefer thicker oil films for better protection and fuel milage is a secondary concern. I will be running Amsoil with no more than 8000 miles or so between changes.
I'm actaully leaning toward the 10W-40 but am concerned about it thickening up from use. I live in CO where it can get cold (but rarely like it does on the East Coast).
Any opinions?

 

[bighead]

Me, I'd stick to a thicker 5w-30 as opposed to diving head first into a 40 wt. If you plan on doing extended OCI's and are worried about the oil thickening (which obviously you are since you are planning on Amsoil [not a knock on Amsoil]) then I'd just run what is recommended. I think the VQ's preferring thicker oil is perhaps due to noise issues (can't say for sure as I don't own one) but I don't think it's due to better wear numbers as is the case with the 4.0L that is in the Jeeps...FWIW.

 

[marco246]

Dude,

I have a new Frontier with the same engine. Have some Mobil 1 5W-30 on hand and will probably use that whenever I change out the factory fill, which has 1300 miles on it. The Mobil 1 5W-30 is moderately "thick" with a higher viscosity at 100 deg C. (11.3 cSt) than many 10W-30s. As for the noise issue, I find the motor pretty quiet unless you stomp on it, and will be alert to any audible differences (obviously subjective) once I change the oil.

 

[427Z06]

quote:

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Originally posted by Dude-Man:
I've been hearing that the VQ's prefer a little thicker oil.

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That may have been the case 10 or 15 years ago with certain Nissan engines, but I don't believe it is true with Nissan engine designs of the last several years. Unfortunately we have only a few UOAs of thinner oils in Nissans since this mindset is firmly entrenched. But the few I've seen indicate that current engines can do very well with thinner oils.

In your case, start with the mid-range manufacturer's recommendation, then after the engine is broken-in and a couple OCIs have taken place, have a UOA with a professional interpretation done. That'll eliminate the personal prejudices, old wives's tales, and other anecdotal evidence not worth spit.

 

[Dude-Man]

Sounds good guys.
I changed out the factory fill at 1204 miles with 10W-30 Amsoil (had a bunch laying around). Ran that for a couple thousand miles as a 'flush fill' and changed again with same stuff. Will run an analysis or two over the next 7500 miles so we'll see what happens.