Yes, I have.
In my defense I'll mention that when I took delivery of the car I did not have an SVT supplement. When I did get the supplement and read that 91 octane or better was recommended I had already run about a dozen tanks or 87 through it. At that point I tried a few tanks or premium and found that there was no difference in performance or fuel economy.
During the life of the car it has had maybe 20 tanks of premium. It now has 131,000 miles on it. I have only heard a very light ping twice, both times on light acceleration on unseasonably warm winter days.
Also, I go out of my way to keep everything very clean in the engine. I clean the throttle body often, clean the injectors often, and change the air filter every 15,000 miles. Oil and oil filter every 3,000 miles. Annual coolant changes. If there were a bit of carbon build up in the intake ports or in the combustion chamber higher octane might be needed. Don't forget that the compression ratio isn't that much higher on the pre 2000 SVT. Non SVT was 9.8:1 and SVT was 10.0:1. The 2000 SVT may not be quite as tolerant since the compression ratio was raised to 10.25:1.
It may not work for others, but it works for me. Believe me, I know and understand the damage that can happen from detination from the wrong fuel and I would not be using the lower octane fuel if I felt there was any real risk.
My main point in my original post on this thread is that I doubt that his problem came from one tank of 87 octane fuel.
