I ran mobile 1 for two oil changes, just switched to the dealer 0w-40 pennzoil. I think the jeep runs better with the pennzoil. It could all be in my head, but it feels different. I changed the factory fill oil at 300 miles. Ran Mobil 1 0w-40 until 9k miles. Have 600 miles on the pennzoil now.
The pennzoil 0w-40 does exist. I saw the 5 gallon container and read it with the techs during my last oil change fiasco. It's a new product, maybe a dealer only blend? I don't know. But, I've yet to see any quart sized for sale at auto stores.
I'll stick with pennzoil with the WK2 since thats what the SRT engineers recommend (per recent chat session, info a couple post up). For the WK1 it was always mobile 1 for my 07.
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