I have been collecting some information that presents a different viewpoint about Amsoil than what has been presented here and in other threads.
Many people trust and use Amsoil signature series 5w-30. I myself was one of those people, but I am beginning to think very differently about this oil, and will probably not use it again.
First, I'm NOT saying that this is a bad oil and that you should stop using it immediately. But the data I am finding is suggesting that Amsoil signature series PAO oil 5w-30 is probably NOT the best oil for GDI motor applications, actually, it has a couple very negative characteristics when used in a GDI motor.
CALCIUM content in oil :
The currently available literature, white papers, and industry leading research projects have definitely noticed the high failure rate of GDI engines and looked into possible causes. There was found a positive correlation between the amount of calcium in the oil the frequency and duration of LSPI, knocking, detonating, and super knocking events. More calcium, more knocking. The research concluded that you should avoid oils with high calcium content.
On both my used oil analysis and virgin oil analysis of Amsoil signature series 5w-30, they report about 3200-3500 parts per million. The very popular Pennzoil platinum oil is around 1800-2200 PPM. So why would we want to use Amsoil oil that has almost twice the calcium content in it and that could stimulate LSPI and engine knocking??
ENGINE KNOCK AND PING :
My first tune was a BTRcc canned tuned and it worked. I was running Amsoil 5w30 and the tune was pinging/detonating while accelerating. On a hunch we changed the oil over to Penzsoil and immediately the pings went away.
FUEL DILUTION :
I send my oil to Blackstone and we've established that my car regularly sees about 4% fuel dilution in the oil. Consulting with Hyundai tech line and my dealership they said this is normal for GDI motors, and to get used to it. My issue is that with that much fuel in the oil, Blackstone is reporting that the viscosity of the Amsoil has dropped to a 5w20 viscosity oil after only 3500 miles of usage.
My Pennzoil used oil analysis reports did show fuel dilution but the viscosity was still stable, and had not dropped below 5w30... Why is the Amsoil so susceptible to fuel dilution, don't we want to avoid this characteristic of and oil in GDI motors?
My concern here is that with the lower viscosity you have a thinner oil film and less film strength to hold up again high sheer and high direct pressures, thus less engine protection.
LOW COMPRESSION :
When we got the last oil report back we decided it might be a good idea to check all four of my cylinders compression.. We did and they read at 155-160 psi compression, which is low. That day we swapped out the 3500 mile old Amsoil and dropped in fresh 5w-30 penzsoil... All 4 cylinders came back up to 174r-178 PSI.
EXHAUST / PAINT CONTAMINATION:
Every time I ran the Amsoil the back hatch of the Veloster, windows, paint, and exhaust would be covered in a yellow nicotine colored oil-like residue that would not wipe off. I had to use a degreaser / detergent at 100% strength to get the exhaust oil residue off.. It didn't matter if I was driving aggressively or slow there was still a residue afterwards. When I switched to Penzsoil, the only residue was little black soot dots that rubbed right off.
All these observations add up to one seemingly obvious conclusion. That with the high calcium, easily diluted by fuel viscosity, and other mentioned drawbacks, that Amsoil is exactly the type of oil we should be avoiding? Even though it is a PAO oil, that doesn't offset the other disadvantages...
Update: Penzsoil for 3 weeks now and my catch can's are not nearly as full as they usually are, and my pinging knocking noise is still gone...