ByByBMW

All good questions and I will try and give you at least one answer in the same vein you asked the question.
Have I ever seen evidence................? No. All evidence I have seen says Mobil1 is a pretty good oil.
It's fairly common knowledge that Mobil had the deep enough pockets to get the contract for the factory fill oil. And their oil really is pretty good. If I hadn't done years of reading info on the web about oil, I would probably have the same attitude as you.. That is, if it's good enough for Corvette/GM engineering, it's good enough for me, and I would be happy.

But, Being in the Navy then in civilian nuclear power, it was ingrained in me to ask questions about everything, never accept good enough always strive for the best and safest solution. Even if it wasn't an obvious problem.
That fell over into my own world and I came across Amsoil, then Redline and Royal purple. Now there are also Castrol and Pennzoil synthetics. So I looked at all of them. My initial choice was Amsoil which I have used in every car I have owned since the early 80's, and no problems. Lately, i have perked up my ears about Pennzoil Platinum and Ultra. I will probably start using the Platinum because I feel it is that good. Now based on my training, you would think I should have to use whatever is the most expensive. Age, (and retirement) have allowed me to modify my thoughts a little and allowed me to use the best that is available, that I can afford. I feel that if you lump Mobil1 with Amsoil, Pennzoil, Castrol, And all other synthetics out there, Pennzoil Platinum is probably the best bang for MY buck, (but still feel a lot of loyalty towards Amsoil).

So, my choice is based on Gm engineeering requirements, bolstered by my own research, and since Mobil isn't paying me to use Mobil1, I choose to use something else just as good, and probably, IMHO, better, at the same price point.

Does that help?

AirBusPilot

^ I don't get why pennzoil makes platinum and ultra. I've read their explanation and they say the ultra is superior, but they are vague on why platinum is still available.

I'm guessing it has to do with remaining price competitive with M1 at walmart. Those that are more educated on oil will pay a little more for ultra, amsoil, etc. Those that just want a synthetic oil and shop price probably get the platinum. I dunno.

EX1

The general understanding is that Ultra also has longer periods between oil changes even though it is not marketed as such. The UOAs for Ultra after 8-10k miles have been very good.

EX1

People are not saying that M1 is not good "enough" for the car. Other people such as myself have had oil analysis done and have had the same if not better results with other oils. M1 is a great oil, nobody is discrediting that oil.

Edge and Ultra have both had great reviews and tests on bitog. There is not a lot of information regarding LS7s and Edge but from the UoAs I have seen from other high hp applications, it is a superior oil to most in my opinion. There is some gray area regarding the advertised oil change intervals though. Most people have needed to change it around 10k miles instead of the advertised 15k. Again that all depends on the cars operating conditions but you get the point.

AirBusPilot

I had it analyzed at about 3700 miles and all was great except some mild viscosity loss. BlackStone told me not to worry about it, but check it again at 5k miles. I just went ahead and did an oil change at 5k miles instead.

EX1

That is good. Try Ultra next time and compare the results!

AirBusPilot

I'm thinking all the premium GM4178's will test similarly, though I'm also thinking the mild viscosity loss was because it's a GRP III oil (I think).

Geardo

I agree, Mobil 1 has been surpassed by most major brands of synthetics

BSSN

I have yet to see a car that wore out due to poor oil being used as long as the weight was correct for the application, it wasn't run dry, etc.

I think the main benefit in picking the "right" oil for the user is determining how long you want to run the oil. If it is an NA application and you want to change it every 3K miles, I think regular dino oil would do fine. If you want to change it every 5K, then look to a good synthetic. 8-12K? A true group IV.

Other than that, it's just finding what your car likes. I experimented with Mobil 1 5-30EP, Castrol 10-30, Castrol 10-40, and found that the Castrol 0-30 was the best in my old LS1. It used the least oil with it (1/2 qt every 4500 miles or so, compared to the 5-30EP Mobil 1 at 1qt per 2200 miles or so). It also ran the quietest.

AFVETTE

I've used nothing but the factory fill (Mobil 1) on every vette I've owned since 1995. I also track my vette's and again I use Mobil 1 5-30.

When GM suggests something else or makes the change themselves than I will.

Tom

bass mechanic

i have a question for you.
i am sure you read the thread about lifter ticking. i have found that on my Ls7 the lifter noice everyone complains about was significantly reduced with 15W50 mobile one. i would really like to run somthing less thick like a 5W30 and i am wondering if its possible that its not the viscosity but some other chemical in the oil that perhaps adds some quality to the oil that allows the engine to run with less noise that is unrelated to viscosity.
you said the castrol ran quieter despite it being a thinner oil than others you tried.
can you explain why that would be?
i am seriously considering switching to a different brand and would like to stay within the manufactutrers approved oils.

BSSN

Castrol 0-30 EU is thicker than the other oils I tried except for the 10-40, which was actually the oil the engine was loudest with. Lifter tick in an all-aluminum pushrod engine is normal.

FrankTank

Thanks Yes

Thanks, makes sense.

3 Z06ZR1

My ls-7 is really noise free. No noticeable noise's even with leaving the plastic covers off. I use Edge. My Tuner put in Mobil 1
when my clutch was changed. It's going back on edge when the time comes.

BSSN

I have never heard an all-aluminum pushrod engine where you couldn't hear the lifters on a free-rev decel from 2500-idle. Maybe when I get an LS7 I will hear one.

NORTY

Neither!