Buick 2011 Regal - Manual (Page 229)

Driving and Operating 9-41
The 8th digit of the Vehicle
Identification Number (VIN) shows
the code letter or number that
identifies the vehicle's engine.
The VIN is at the top left of the
instrument panel. See Vehicle
Identification Number (VIN) on
page 12‑1.
Vehicles that have a FlexFuel badge
and a yellow fuel cap can use either
unleaded gasoline or ethanol fuel
containing up to 85% ethanol (E85).
See Fuel E85 (85% Ethanol) on
page 9‑43. For all other vehicles,
use only the unleaded gasoline
described under Recommended
Fuel on page 9‑41.
Recommended Fuel
If the vehicle has a 2.4L L4 engine
(VIN Code C), use regular unleaded
gasoline with a posted octane rating
of 87 or higher. If the octane rating
is less than 87, an audible knocking
noise, commonly referred to as
spark knock, might be heard when
driving. If this occurs, use a
gasoline rated at 87 octane or
higher as soon as possible.
If heavy knocking is heard when
using gasoline rated at 87 octane or
higher, the engine needs service.
If the vehicle has the 2.0L L4 engine
(VIN Code V), 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 the vehicle's acceleration
could be slightly reduced, and a
slight audible knocking noise,
commonly referred to as spark
knock, might be heard. If the octane
is less than 87, a heavy knocking
noise might be heard when driving.
If this occurs, use a gasoline rated
at 87 octane or higher as soon as
possible. Otherwise, you could
damage the engine. If heavy
knocking is heard when using
gasoline rated at 87 octane or
higher, the engine needs service.