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Hello,

Owner of a 2019 XC90 T5 Momentum AWD in USA. I have been putting 87-89 octane fuel in my car for the past couple of years, and just now noticed that the fuel lid says 91 octane.

I have switched over now, but just worried about a couple of things:


1) Have I caused some long term damage to the engine?
2) Is there any risk to my warranty due to this? I have been getting the car serviced regularly and have not heard anything from the dealership.


I really love the car, haven't had any major issues with it yet!

Thanks :)
 

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Your car has a knock sensor which causes the timing to be retarded to compensate. Lower gas milage is the only result of running 87.
 

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Now that you've realized the required fuel octane, you should keep at 91+. As you've noticed Volvo lists it as the required minimum octane where as on older Volvos it was the recommended minimum. The engine design is different and while it's true most modern engines have engine management that can retard the timing to allow for variations in octane to avoid premature detonation of fuel (knock) it's typically to adjust for it within an operating range. If the requirement is 91+ now, we don't know how much of a tolerance it has. If you've not noticed knocking while running the cheap stuff, that's a good sign but not a sure sign it won't happen. The VEA engines were designed with different combustion modes and under different conditions it may not have as much tolerance for lower octane.

@TheWhiteWhale found some great technical documents about SPA XC90 and the Powertrain section specifically talks about the different combustion modes the engine has.

 

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No risk to warranty unless it were to be determined that the gas caused the problem... and I've never seen or heard of that. We do sometimes see check engine lights on some older drive E cars that we think has to do with gas, but it's likely as much the cheap low detergent discount gas than the octane. Volvo does also recommend using Top Tier rated gas. It's a direct injection motor so it doesn't hurt to do some induction cleaning now and then as well.
 
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Posting here as I read this for T5s, Volvo site:

Volvo recommends premium, 91 unleaded octane or higher for optimum performance, but your Volvo can run on regular 87 unleaded octane without affecting engine reliability. It is safe to use fuel containing up to 10% Ethanol in your Volvo.
Fuel Requirements (custhelp.com)
 
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