DANG! ... @
iamhubert ........ I sure hope you don't carry your paranoia into the dealership with you.
What you might do is to create a journal, with the dates of what you did, service wise with your car, along with the receipts for purchase of oil and filters.
This will make it easier for the dealership to document the service.
When you have the car taken in, I would just say something like ...... my car stopped running and I have no idea why. I would like it fixed.
If you are all defensive up front, mixed in with paranoia, they may suspect you aren't telling them the whole story.
Now, it's there move.
IF they ask about the different weights of oil you used, just be honest with them.
I have a feeling the dealership will do the right thing and fix your car, with no out of pocket cost to you.
humfrz