Just bought a 2003 c70. manual says it need premium gas. True? what happens if i use reg unleaded?

 

Anything less than 91 octane, I think you run the risk of pinging (pre-detonation) that can damage the turbo and engine if left that way for long term. Once in a blue moon, you may get away such as needing gas in an emergency and can't afford or find 91+ octane. For any gas below 93 octane, you will generally lose horsepower as the engine is not efficiently burning the gas, so you might be only making 210hp instead of 236hp. I believe forced induction systems are more sensitive to octane ratings than NA due to the high compression and fuel mixtures.

 

The Volvo has a knock sensor and so there is no problem with using regular fuel what-so-ever. However, the mileage and performance are affected when using regular and I believe that you will find it is cost effective to use the premium. Shell gasolines put valve cleaners and injector cleaner in their premium grade and not in regular or midgrade...............according to the Shell dealer I trade with. That alone should be reason enough to use premium.

Reg.

 

True, most cars have a knock sensor in them, but the ecu can only retard the timing so far before detonation occurs regardless, especially if the gas is the 'ole no-name 81 octane price special. For short term driving you can get away with it, but if constantly in use you will run into problems. Your car will run like crap and you may actually need more gas that offsets the savings to begin with. As for the detergents in the gas, some is OK, but too much can also deride the purpose of the premium fuel. Mobil had problems back in the eighties I believe because they purposely added extra detergents in their fuel and used that as a selling point, hence the swishing gasoline in the 'O' of the Mobil name in the old tv comercials. But, the more detergents added, the less effective power or BTU ratings the fuel has and it becomes harder to burn. Some people stopped using Mobil because it was it was the equivolent of weasel **** at that time. Things have changed for Mobil since then, namely the buyout by Exxon and the re-engineering of some of the additives to interfer less with the power output of the gas. Also remeber the extra additives will make the fuel cost generally go higher for those companies in comparision to others in certain cases. The general rule is that if the factory recommends a certain rating for the engine, then try to heed that as much as possible to keep a smooth running car. Otherwise you maybe asking for trouble down the road that may take away any savings you had before from the pump with the lesser octane fuel.

- Henry

 

I use mid-grade with no persivable issues!Mid-grade works just fine.

 

My '01 V70 non-turbo manual says 91 is recommended but requires a minimum of 87.

 

I have slowly been going from 93, to 89, to 87 and I can tell you first hand under constant driving conditions through all three grades, the mileage has dropped each time. The engine idle and smoothness seem to be unaffected. There is also a slight power drop from 93 to 89, but definitely more noticable from 93 to 87.

 

I think it all depends on whether you want to save money or save time between fill-ups. I'd rather run the 93 we have here and justify the extra cost by the extra mileage I get per tank and not have to go back to the pump as often.

 

Just from my average results though, I would say, at least with my car, you get what you pay for and the $$ per mile is about the same going through all grades.

 

okay.....i did a little experiment after reading your posts......i ran my car on the highway with straight 87 octane....i reset the trip computer and put it on cruiseat 70....i was getting about 20 mpg on the highway with the 87 .....i then put in half a tank of premium 91....so in essence i ran on 89 octane since they were mixed.....with that i got 27-28 mpg on cruise on 70.....doing the calculations.....there is maybe 30 to 40 cents difference in price. per gallon..thats about 10 percent price difference total.....but the gains are abour 30 percent in mileage....and thats with 89.....im eager to try with just 91....does this sound about right to you guys?

 

That seems a little extreme for a mileage improvement based on a 2 point octane change. Was the outside temp the same? Were you going with or against the wind both times?

 

dont know what to tell you....i was going one direction with the 87 and the opposite direction with the 89.....plus one time was in the afternoon....the other in the evening....you think temperature was a major factor....i doubt wind effects it that much but i can see your point with temp

 

I was just wondering that's all I don't doubt anything these days.