Originally Posted by SRT6_Roadster
In addition when the last generation RX-7 was undergoing testing a single synthetic oil resulted in engine failure. Nissan at the time took the route of stating that no synthetic oils were approved for the car. I have been led to believe the oil in question was Castrol Syntec.
I'm sure that you mean Mazda, the manufacturer of the RX-7 and other rotary engine equipped vehicles.
As for me, I swear by Mobil-1...but I have also sworn at it. I had a '90 VW Jetta a few years ago. It was a great runner and I planned to keep it for a long time. So one day I changed oil and filled her up with Mobil-1. At first I only noticed a bit more lifter noise on cold startup. A month later the oil idiot light came on while driving about 25 MPH and the nasty low oil-pressure alarm sounded. I immediately pulled into a service station to check the oil. The stick showed full, and the oil looked and smelled normal. Still, from that time on the Oil light flickered at idle, and the low oil pressure buzzer sounded at low speeds whenever I'd driven more than 30 minutes or so. Of course I drained the Mobil-1, never using it in this car again. But...the "damage" as it were, was done. The car was never the same again.
So why do I still swear by Mobil-1...I guess because I felt it was a freak event, but more than that, I bought into the Mobil-1 story from the first Popular Science article in 1976. That was an amazing article, and other than my Jetta, I've had nothing but good results from it.
As to Castrol, until this thread I'd never heard a disparaging comment about it. In fact, that's what I used in the Jetta while it still ran...and in the end it was a wreck that killed her...with the low oil problem still plaguing my son to whom I'd turned over the keys.