| Re: Cadillac Owners Manuals - Download
From the 02 STS manual:
Use regular unleaded gasoline with a posted octane of
87 or higher. However, for best performance and for
trailer towing, you may wish to use middle grade or
premium unleaded gasoline. If the octane is less than 87,
you may get a heavy knocking noise when you drive.
If it is bad enough, it can damage your engine.
From the 08 SRX manual:
If your vehicle has the 3.6L V6 engine (VIN Code 7),
use regular unleaded gasoline with a posted octane
rating of 87 or higher. For best performance or trailer
towing, you could choose to use middle grade 89 octane
unleaded gasoline. If the octane rating is less than 87,
you might notice an audible knocking noise when you
drive, commonly referred to as spark knock. If this occurs,
use a gasoline rated at 87 octane or higher as soon as
possible. If you are using gasoline rated at 87 octane
or higher and you hear heavy knocking, the engine
needs service.
If your vehicle has the 4.6L V8 engine (VIN Code A),
use premium unleaded gasoline with a posted octane
rating of 91 or higher. You can also use regular
unleaded gasoline rated at 87 octane or higher, but
your vehicle’s acceleration could be slightly reduced,
and you might notice a slight audible knocking
noise, commonly referred to as spark knock. If the
octane is less than 87, you might notice a heavy
knocking noise when you drive. If this occurs, use a
gasoline rated at 87 octane or higher as soon as
possible. Otherwise, you could damage the engine.
If you are using gasoline rated at 87 octane or higher
and you hear heavy knocking, the engine needs service. | 
Re: Cadillac Owners Manuals - Download 
