Winter blend gas?

[loud2004marquis]

I've heard of winter blend gas being lower than advertised octane. Was wondering if anyone knows if you had a 93 octane tune in a daily driver, should you get a different tune setup for the winter?

Not sure if this matters or not; but it would be for a non-boosted application. Stock except for a tune.

[boatmangc]

I know that crap is driving me crazy down here, Marne engines, 80 degree ambient temps, our winter has been non existent but we still get winter blend.
Vapor lock anyone?

[RF Overlord]

I've heard of winter blend gas being lower than advertised octane. That's not true, and in many states would be illegal.

The difference between summer and winter blends is the Reid Vapor Pressure, which is the tendency of a fuel to evaporate. The RVP needs to be lower in summer to keep the lighter components from boiling off due to increased ambient temperature. Nothing to do with the octane rating.

[loud2004marquis]

I see...thanks for the clairification. Learn something new everyday!