Wrong oil?

Eris

Good day,

I take my car to be serviced at dealerships; warranty requires so.

When driving, from a cold start all the way up until the oil temp reads 190 - 200, I have adequate, normal power. As soon as it goes above 200, there is a massive loss in engine response... feels like I either lost 50 Hp or there is something wrong with the throttle. It doesn't get too hot. My max oil temp is 230... it usually sits at 220. So its not over heating...
The throttle bodies...fuel injection...fuel pump... etc... no leaks and everything has been cleaned (this due to another issue that arose when I had an error with a Maf sensor, but that was done with and no codes at all anymore).

I was told that perhaps the dealership just used a different oil, given that they have drums of it and don't stock up on more expensive kinds... so they use the same one for the whole range... so by using the wrong kind of oil, it doesn't have the right viscosity when it heats, and thus the VVEL system doesn't work too well. How likely is this?

Its quite annoying... car pulls hard only the first 20 minutes and then feels like a lesser car than it is.

Thank you for your time.

Sent from my SM-G985F using Tapatalk