With the awesome help of everyone in the forums I hope to drive my 57 around the area before doing a complete restoration. I know we touched on this slightly in another post but I am curious what I should use for fuel. Most gas stations in California sell 87, 89 and 93.

- Should I be using 93?
- Should I add an additive, if so, is there a specific one everyone likes?
- Should I re-add the fuel filter that was placed between the fuel pump and carb. I removed when I was having starting issues.

Thank you in advance for any suggestions.

 

Look in your service manual and it should tell what your engine's compression ratio is. If it's 10:1 or higher use the highest available octane fuel you can get. 9:1 range you may be able to get by with 89 octane but you want the lowest octane that doesn't cause detonation or dieseling. You have to consider California fuel blends too as they are formulated solely with emissions in mind, not driveability or performance.

Putting a new filter inline shouldn't affect anything and will for sure make the inlet screen in your 4GC stay clean longer. Metal body or transparent plastic only. No 3-piece metal and glass job. That's a fire looking for a place to happen. Some of us put it on suction side of the fuel pump, since a good strong f/p should be able to pull fuel thru it.

 

The 1957 Oldsmobile shop manual shows a 9.5:1 compression ratio for all series. (Vehicles produced for use in USA.) The owner manual for the 1957 Oldsmobile indicates that "premium" fuel should be used. This will likely translate to 93 in today's fuels. You might be able to get by with 89, but as noted, pre-ignition or knocking should always be avoided. If possible it's best to use non-ethanol fuel.
A fuel additive is not needed unless you want to pursue a particular task like added upper cylinder lubrication or higher octane rating.
The fuel filter can do no harm and may help to keep the carburetor cleaner.

 

Ozzie, thank you. I'll start putting premium fuel in the Olds moving forward without the additive. I'll also re-add the filter just in case to keep the carb cleaner. Thanks for the advice.