I would have answered to go with the QHP 2 days ago but now I say the PP. While I still think the Q synthetics are good oils I am very dissapointed in what I saw in an engine run almost exclusively on it in total, and solely on it for the last 2 years +/-, 2 days ago. It has dropped way, WAY, down on my list now.
I had my Sister stock up on it when AutoZone had such a great deal a couple years back( 5qts w/ filter for $19 ). She has been running it ever since in her 06 3.5L Impala( not known to be hard on oil )and so has her husband in his truck( 06 Colorado I5 ). I was going to have them start using the new Ultimate Durability( renamed/refomulated HP )but not now. I am going to be borrowing her car for a trip so I was doing some maintenance on it as a thank you.
I was working under the hood and on a whim I pulled the oil filler tube( it unscrews )just to have a peak and see how the top end looked( you can actually see quite a bit through the hole surprisingly ). I was SHOCKED to see the valve train all varnished up( VERY dark! ). I also saw what appeared to be some deposit build up. This is a completely healthy engine with no fluid leaks or anything else wrong that would lead to either conditon. The oil in the crankcase at the time was approx 5 months old and about 4K worth of use. The engine is not known for being hard on oil as I said and the vehicle is not abused/beat on either.
I am not impressed with how the oil performed in "this" application. I actually have run it in other things and felt it did much better. The engine didn't blow up but it is filthy inside at just 27K( approx 24K on QHP only ). I have torn down motors with over 100K run on cheap dino oil that had a cleaner valve train than her car does.
What does that say for her lower end and oil pan condition? I may end up pulling the valve covers to get a better look but really I saw enough through the fill hole to know it won't make me happy. I am going to take a look at her husbands truck to see what it looks like next. He runs the oil 7-10K between changes. I am almost afraid to look as I am the one who recommended they run it.
I added some Seafoam and took it for a good cruise down the highay, then let it run at idle for about 30 minutes, to try and clean it out. I then did a swap over to Kendall GT1 synthetic. The Seafoam seemed to remove the deposits I had seen but the valve train is still all varnished and dark.
I know that doesn't mean anything supper bad but it doesn't impress me or mean anything super good either. This out of a supposdely top quality synthetic changed every 5K. I would expect better out of a dino oil in an engine with so few miles that has been cared for as well as her car has.
I may at the next OC for her suggest she do an Auto RX treatment. I wanted to send off a sample of her oil for analysis but I didn't have a kit and I was under such a time constraint I said forget it and just changed the oil.
Hoping the Kendall does a better job.