3.9

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How sensitive are the 3.9 engines to oil viscosity? I've read that you absolutely have to use 5-30 in my 08 impala but I have 10 jugs of PP 10-30 that I wanna use up, probably next summer and fall. I have disabled the active fuel management if that matters, but believe it or not, this is my first Chevy @46 yrs old. Anyone have some testimony here?
 
there is no real difference in viscosity between 10w30 and 5w30 until its below 0f out.
use accordingly.
 
I figured as much but many on the impala forums state that the vvt is sensitive to a 10w.
 
Originally Posted by Rand
there is no real difference in viscosity between 10w30 and 5w30 until its below 0f out.
use accordingly.


Very true. To muddy it further, lots of Xw30s shear down to a 20wt anyway!
 
I have the 3900 in an '06 Malibu. Probably the same basic deal other than the cylinder deactivation on yours I bought mine used in '09 with 18k miles. It was a bit of an oil burner right off with 'in town' driving, but not that much on the road. I figure it had 5-30 conventional oil and I went to 5-30 synthetic and at 82k miles, it will yet burn a quart in around 2000 miles.all along. Maybe next year I'll run some 5-40 Rotella
 
Originally Posted by D1dad
I figured as much but many on the impala forums state that the vvt is sensitive to a 10w.

That's not possible. When oil is cold all winter grades have a high viscosity and apparently most vvt mechanisms are inhibited when cold anyway. So the winter rating is irrelevant to vvt operation.
 
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