Oil for 2005 Impala w/ 3.8 Series II

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Ok, this motor for years was spec'ed with 10w30 by GM and ran for a very long time. They are extremely reliable. My 05 impala has a 5w30 oil cap. I have ran 5w30 for 25K and have not had a problem.

Did anything in the L36 change for GM to recommend 5w30 or is this their way of getting more MPG across the fleet like Ford did with 5w20?

I have a stash of Shell 5w30 that I had intended on using up in this car but with Pennzoil Platinum and M1 coming back down in price, I might switch it over to synthetic. Just wondering what grade to run for the next 100K. I am really interested in M1 0w30.
 
5w is just your cold flow number. Pretty much means you can start the car in colder temperatures and still be fine.

The change probably happened because oils got better. The oils got more shear stable which made making the 5w30 easier. If we ever find a way to make cheap shear stable 0w30s I bet those will be come recommended from oem, but for now they require synthetics and that makes them expensive.
 
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Originally Posted By: wapacz
5w is just your cold flow number. Pretty much means you can start the car in colder temperatures and still be fine.

The change probably happened because oils got better. The oils got more shear stable which made making the 5w30 easier. If we ever find a way to make cheap shear stable 0w30s I bet those will be come recommended from oem, but for now they require synthetics and that makes them expensive.


+1
 
it will be ok to run 10w-30 but i would stick with 5-30 for cold like it said above. or 0-30. or really that motor likes synthetics as well
 
I have a 1999-spec 3800 Series II. It runs fine on 5w-30. I have dino in there right now since it was in the stash. It's seen a little bit of 10w-30 and lots of 5w-30 since it sounds better on startup with 5w-30.
 
Originally Posted By: 04SE
Ok, this motor for years was spec'ed with 10w30 by GM and ran for a very long time. They are extremely reliable. My 05 impala has a 5w30 oil cap. I have ran 5w30 for 25K and have not had a problem.

Did anything in the L36 change for GM to recommend 5w30 or is this their way of getting more MPG across the fleet like Ford did with 5w20?

I have a stash of Shell 5w30 that I had intended on using up in this car but with Pennzoil Platinum and M1 coming back down in price, I might switch it over to synthetic. Just wondering what grade to run for the next 100K. I am really interested in M1 0w30.



0W-30 AFE would probably work great. These engines run fine on either 10W-30 or 5W-30 and my old 1990 Buick LeSabre 3800 actually called for 5W-30. I'd use the Formula Shell in the warmer months and try the 0W-30 in winter...
 
Originally Posted By: Ram01
That's true but plenty of people on this forum may have the wonderful 3800 series from GM. And want info on which grade to use
That's a good point, but there is also this thing called an "owner's manual." Lot's of good info. in there!
smile.gif
 
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