what type gas should i use for 65 mustang inline six....what is the overall diference from using Regularand Supereme

 

The compression ratio of your engine dictates what octane gas you need to run. Your inline 6 uses 87 octane regular because your compression ratio doesn't warrant anything higher. You would be wasting money if you ran anything but 87.

 

what about a 289?

 

How would one go about finding their compression ratio?

 

Here are a few. Any engine with 9.3.1 compression and lower can get by with 87 octane. Anything higher should be using premium.

I200- 8.8.1
I250-9.00.1
289 D code - 9.0.1
289 C code - 9.3.1
289 A code - 10.0.1
302 2c - 9.0.1
351W 2v- 9.50.1
351W 4v - 10.70.1

 

thanks alot