Service engine soon light on approximately 4 days after I changed gas from 87 grade to 89 grade ( my daughter told me I should have been using premium gas, but I never knew). Car is 5 years old has been running fine its starts up the same. I have not been able to get to a dealership to check it out I tighten up gas cap. I am hopeful its a minor problem...but what??

I suggest a tune-up.

87 will be fine. But I always run 89 seems to be a little better burning gas. But with the price of gas these days I'd run 87. Just run some fuel injector cleaner once in a while.

This is true. The only time you need to apply gasoline with higher octane is when preignition is present. If it sounds like marbles are bouncing in your engine when you are driving then get higher octane. However if the car is in good mechanical condition (cooling system, oil serviced regularly) then 89 octane is perfect.

You should always use premium fuel on the high conmpression V8 engine. Cheaper fuel can cause a PING, and possible engine damage. 87 octane is definitely not recommended at any time, but sometimes you can get by with 89 for a small period of time.

Gas mileage and power will both be down with lower octane fuel, so do not use it all the time.

87 octane is just fine for this vehicle, unless you live in a very high altitude location, in which case you may need to run 91 octane.

87 octane ,,,you kidding ---more like 95 octane .But this has nothing to do with the vibration and check engine light,forget having the codes read get the dealer to look at it

I have the exact same problem it took awhile before I figured it out.This car requires the medium octane gasoline .The 87 octane gas causes the engine to run on the lean side and triggers the "service engine soon light".By putting in a higher octane gas (middle range 92 octane) the light won't come on.Or you can get your service mechanic to set a richer gas mix for your car,however you'll lose about 2-3 mpg .

87 octane is ideal for your accent.

It's a little commuter car. It's designed to save you money.
Anything over 87 is just a waste of money, UNLESS your engine is knocking at 87. Then you should step up to the next highest grade.
89 is a made up octane. It's just a mix of the lowest grade and the highest grade. I used to work at a mobil gas station for a year, and the only grades i knew wer 87 and 93, but 89 was an available option. it's just a way for oil companies to benefit off of ignorance.
91 and 93 is for high performance engines, turbo-induction, superchargers, that sort of stuff.
you should be fine sticking with the 87 though, but move up to "89 octane" or 91/93 if your engine knocks a lot.
hope this helps.

Volvo is a good car. if you maintain you volvo by changing the oil on time, maybe after every month according to how you drive and changing you fuel filter, using 93 grade fuel or 89. I advice you to keep your volve. do your oil change on time don't wait until three to five months before changing your oil and don't use poor fuel (87) grade. change your tranmission oil after 18 months then your volvo is yours for life.