850 requires premium (91 octane or better) gas which is getting more and more expensive. What is the risk with using a lower grade gas like 89 Octane (which is better than regular gas 87 octane), any advice and opinion will help me save some money, obviously do not want to save at the expense of major damage.

 

You should not have any problems running 87 octane gas.

 

Thank you.

 

No problem any time.

 

I have recently got an 01 C70 HPT and it asks for premium gas

To start at the beginning, when I collected it (from a very reputable but non-Volvo dealer) it had a full tank of gas, flavor unknown!

I filled it after 300 miles with premium and 20 miles or so later the ETS light came on - no other effects.

So I worried / researched like crazy and asked a question here (Thanks Tech for your answer!!!)

After a day or two the light went off and has stayed off with no action from me.

I decided that probably the car had been run on 87 Octane for a while and the ETS light was the system adjusting its settings for the higher octane fuel.

Questions:

Is that likely?

Can I revert to 87 Octane (not looking for out & out performance)?

That throttle body....I can see a yellow label with part numbers etc on it - when Volvo replace it do they fit a different part number with the problem fixed so I can tell if this vehicle has been updated or not?

 

I forget I hink the yellow sticker is the latest and most updated throttle body's.You might want to have it cleaned.The throttle body's are pretty sensitive.If they get dirty the will sometimes set a code.But if the light goes off after a little while that means the code was present but is not present anymore.After so many times of not seeing the code it will erase.