Good day folks,
Looking to see what the experienced forum members recommend for my 3.7 I-5 2008 H3 (132,000mi).

Recently I swapped oil from 5w-30 penzoil high mileage to 10w-30 mobil 1 full synthetic on recommendation of a trusted mechanic friend. I also swapped out the VVT which was giving me an occasional P0014 code.

Anyway I drove the truck apx 700miles and then got hit with the P0017, and now will give me the infrequent rough start (about every 6th start or so) and even gave me a rough start followed by dying out. The truck drives fine otherwise, in fact has been giving me record MPGs (from 15-16 to 17-18) but Ill clear the code, and then it will pop up again on next start up.

I dropped the truck off at the mechanic who said that his computer advised that the problem may be the VVT, oil, or a timing chain issue. He said his shop doesn't have the capacity to open up the block but said this was the most likely issue since 1. I already installed the VVT, and 2. he didnt think going from 5w to 10w oil will make a difference.

So Im on the fence regarding my next move. Should I swap out the oil back to 5w or throw in the towel and assume I have a timing chain problem.

Just for good measure I took out the vvt to inspect the screens, the sensor was totally clean of any screen obstructions.

Thanks,
Mike

 

Bulletin No.: PIP4945B

 

Just curious as to why you'd put in 10w oil.

 

I live in southern VA, our summers are hot. The mechanic friend I mentioned said a 10w was more appropriate for the summer. I thought, wth, might as well give the heavier oil a try.

 

 

Change back to the correct oil, full synthetic 5W-30. Your trusted mechanic friend is not the sharpest knife in the drawer. When the manufacturer lists an oil to use, you should be using it........

2008 H3 Hummer Owner's Manual
"Look for three things:
• GM6094M Your vehicle’s engine requires oil meeting GM Standard GM6094M. Look for and use only an oil that meets GM Standard GM6094M.
• SAE 5W-30 As shown in the viscosity chart, SAE 5W-30 is best for your vehicle.

These numbers on an oil container show its viscosity, or thickness. Do not use other viscosity oils such as SAE 20W-50"

 

Point taken.

Ill swap out the oil tomorrow. Fingers crossed for a resolution.

 

Gents,

Oil changed.

3rd start up gave me a rough start and sent the code back to the dash.

I think I'm in timing chain issue territory...

 

Did you clean the crankcase? I recommend #1Seafoam or BG EPR. Follow the directions and change the oil & filter.
BG
diy

 

I've never done a crankcase clean.

Only 4.25 quarts of old oil came out of this last change after only 1900 miles...