I'm looking to buy a 2004 C70. Owner's manual says 91 octane recommended. In Volvo-speak, does this mean "required" or just "recommended"? Can I get by with 87 octane?

Any car that requires premium fuel is a deal-breaker for me.

Thanks very much!

 

It is not required. 87 will be fine.

 

I get a definite loss in power if I put 87 in mine. Turbo seems lazier and engine in general is less responsive. Use 87 if you're just daily driving it, but remember to run 91 through it every so often.

 

I would compromise & use 89. Wife's Lincoln recommends 91, we use 89.
13 yrs no problem! I put 91 in about every 4th tank to clean it out and use Seafoam in spring/fall to clean out injectors etc. 1 can in each 3 tank fulls.
JMHO.

 

If you have a definite loss of power with 87, you have other problems going on.

 

I'm exaggerating a bit, and it may just be psychological, but hypothetically what issue would there be?

 

It's probably psychological. You would have something causing knock with 87 and not 91, like carbon deposits or the wrong plugs.

Octane is not a measure of performance or cleanliness. It is simply a resistance to knock.