One might think that a simple specification, recommended fuel grade, would be an easily accessible spec - not so in the Volvo world.

I have been running my 2015.5 V60 T5 on mid-grade (89 pump spec). It runs smoothly and I typically see ~ 35 mpg highway consumption. I was thinking about this yesterday as my tank neared empty, wondering if that was the optimal spec.(Fifty years ago my SAAB 99 had "knock" sensing capability and could, within limits, adjust operating parameters - probably spark advance - to accommodate different fuels.) Might the Volvo have a similar function?

I pulled out my owner's manual. The only fuel related number I could find was tank capacity. There was, of course, about 15 pages devoted to fixing a flat tire. The "on-line" manual advised that 87 RON was the minimum acceptable and two motors, identified by part #, not fitment, were high performance and required "premium" fuel.

As an experiment, I filled up with 93 octane fuel to see if any differences are revealed. I only drive about 5000 miles/A so the cost difference is not a significant factor.

Any insights?

 

Fuel Requirements is what I think you are referring to...

You may find the RON recommendation inside the filler door as well but you are correct in noting the engine management system does have knock sensors to detect misfires which provides feedback to the FI and ignition to either retard the spark and/or enrich the mixture (which cools the cumbustion). The article also notes that premium fuels (particularly big brands) also contains more detergents than regular unleaded so even if you drive around on 87, its recommended to throw in a tank full of name brand premium. Consumer Reports published a test where they showed it only takes 1-2 tanks of premium to get the full benefit of the detergent's action. SO what's the difference - To most it really depends on how you drive. If your car is rated at say 200 HP on premium, you may only realize say 180 HP on regular due to the retarded spark during WOT. Most daily driving barely uses more than 50 HP so for all that time, the extra octane is providing no value add. The energy density of premium vs regular is only a fraction of a point - where ethanol is about 85% as dense as octane so you may want to look for a brand that advertises low or no ethanol (not sure if this is possible any more..) For those who swear they get 1-2 mpgs better gas mileage on premium, I dismiss that as being without science :-)

 

Thank you. That is exactly the information that I was seeking. It does seem to me that it merits inclusion, perhaps in bold letters, on the first page of the "Specifications" section of the manual since the most common non-driving interaction one has with one's car is filling the tank.

I wonder if the additional detergent in premium gas has any effect on spark plug life? In the days when my Austin Healey 3000 was my only means of transport, I discovered that the combination of NGK plugs and Amaco lead-free gasoline significantly extended the time between plug changes.

 

with modern FI engines, the fuel metering is very precise so plugs generally last 50-75K miles. best thing to do is to go with factory maintenance intervals and stick with OEM plugs as that way you get the correct temperature range and proper spark across all driving conditions. If your plugs were to foul, it would likely be due to fuel mix issue, coil issue or perhaps an oil consumption issue - any of which would probably trigger a misfire fault code. Just recently on my car I got a P0303 - misfire #3 and it was due to the coil pack giving it up at 95,000 miles. Replaced the coil and good as new. Back in the day I owned a series of BMW 2002s where I was always tinking with points, changing out plugs for winter/summer temp ranges etc... now its just changing parts when they break or when the maintenance recommends replacing.

 

I'm also trying a bit of an experiment. In my area we only have grocery store gas stations and although they may have the detergent that satisfies the EPA they don't have the top Tier detergents as Top Tier stations. So I was in an area the other day and I tried Top Tier same octane as I normally use.

Just get a tanker driver to talk about this and he'll tell you that yes the gas may come out of the same storage supply but while the gas is pumped into his tanker truck there is also another hose supplying the required additives. It is those additives that make the difference between top Tier and non-Top Tier gas. My driving habits are terribly hard on the engine, short trips, tank of gas shows average MPH at 19-20. So I'm thinking that maybe a bit more detergent might be a good idea. My car isn't running the same as it did when I bought it in March 2019 (getting onto freeway I need more pedal). This is my first tank and I plan on filling up with Top tier gas and I'll see if there is a noticeable difference after several tanks used.


""Top Tier gasoline must contain more deposit-fighting detergents, it also must be sold at all of a fuel marketer’s stations and across all grades of its gasoline, from 87-octane regular to top-of-the-line premium. Additionally, to earn the seal of approval fuels cannot contain metallic additives, which are potentially harmful to automotive emissions-control systems."

Inquiring minds want to know why all we have are stations that are linked to food?

Tanker guy Billiy says --

"On the premesis of the loading rack are several large tanks which can contain everything from gasoline to additives, to which once the fuel starts flowing from the storage container, different additives can and do flow from the some of the tanks on the premesis. Yes the GAS may all be the same, however the additives and amounts can and do differ."

Hm????

"Chris Martin, a spokesman for Honda said “we’ve supported it [Top Tier gasoline] because we’ve seen a benefit from it for our consumers in the long run.” He also said the average driver doesn’t know about detergent additives, they just look for the cheapest gas available but “Top Tier fuel goes a step beyond that.”

“We don’t require that our vehicle owners use Top Tier gas” Martin said, but it helps “make sure the engines are going to last as long as they could.” This is obviously beneficial, especially since Honda drivers historically keep their cars for a long time.

Responding to questions via e-mail, Marie Valentine, the Senior Principle Engineer, Vehicle Regulation and Certification Engineering, Toyota Technical Center, said the amount of detergents in Top Tier gas is about twice what’s required by the EPA. However, it can vary depending “on the base gasoline and the chemistry of the detergent additive.

When asked about the price of Top Tier Valentine wrote, “Toyota does not comment on the true cost. However, generally there is no change between TTDG [Top Tier Detergent Gasoline] and normal LAC [Lowest Additive Concentration] gasoline,” good news for consumers wanting to keep their vehicles for many years.

Top Tier is all about keeping engines clean. As far as fuel economy is concerned, it should perform identically to gasoline with lower levels of detergent, so don’t expect a big efficiency boost.”

"Top Tier fuels feature more of these additives than regular gas. In 1995 the Environmental Protection Agency (EPA) set a minimum standard for gasoline additives. Since then, refiners and fuel blenders have actually reduced the amount of detergent they put in fuel by about 50 percent. In the long run this cutback has impacted the ability of vehicles to meet emission standards.

According to Bill Studzinski, Fuels Technical Specialist at General Motors, a number of OEMs saw this problem and got together to push for higher levels of detergency. He said Top Tier gasoline is a better fuel for engines, and that it takes the mystery out of what a good fuel is and what an average fuel is."