What About Gasoline Ratings

[Frankie L]

OK ........Heres a good question................What is the absolute low down on using Premium gas, I've used Sunoco Plus, 89 Octane in both my 325 & 525 and to date have never had any problems, pinging, loss of power, etc ???????. When I look at the rated horesepower of 184 BHP in the 25's I don't know why I just can't used regular.............Any answers would be much appreciated

 

[northyork]

I find that I get far better gas mileage using super over regular. I didn't notice much by way of power loss. I figure for the few extra bucks at the pump it's worth the peace of mind that I am providing for some preventive maintenance.

 

[Average Jae]

sounding like a broken record here again..

modern cars don't PING, or KNOCK! they have a knock sensor which retards the engine perf if the engine happens to run too hot for the fuel you are using. (higher octane rating basically means, higher heat tolerance before the carbon chain breaks.) if an engine normally runs hot, (designed that way to extract as much perf as possible) the fuel may prematurly combust before going into the firing chamber if the octane rating is too low. causing the knocking sound. knock sensor detects this, and makes sure the engine runs at a lower temp, (at less than peak performance) so there is no premature burning.

the drop in perf thanks to the knock sensor may not be too noticible, but as i've been asking for a while now, why would you spend extra money for higher perf (namely the 3.0 i6, or the 4.5 v-8) then be a miser about gas prices to lose performance? that to me is the dumbest thing, but most people cite couple bucks saved at the pump and lack of the knocking sound to justify such dumb decision.

btw, as unscientific as it maybe i agree w/ Todd (northyork) about super getting better gas milage. (this isn't a point of argument, just my observation from dring different cars and filling them up w/ different gas.)

 

[codex57]

I get better gas mileage. Depending on the car, the difference can be from a little to a ton. Oftentimes, what you lose in gas mileage wipes out any savings you get in the cheaper gas price.

 

[bahnstormer]

did u read your owners' manual?

 

[midtownkoi]

Heard a story, not sure if it's true, from the place I get my gas from. They had a customer that had a leased Mercedes Benz, and they always used regular, even though the manual and the gas station owner said that they should be using premium. When the car was turned in after the lease, Mercedes Benz ran some type of test and found out that the engine had been damaged due to the use of the wrong type of gas. The car owner had to pay for all the repairs to the engine, which was way more than they saved in using a cheaper grade gas.

 

[Frankie L]

Thanks all... for your comments. I'm convinced.....................Effective immediately I'll be using Premium

 

[connectionsav]

After asking more then a handful of VW mechanics they also told me that higher octane fuel will give better milage because it gives better (more efficient) burn and produces more power. This in turn gets you there quicker and with less foot into it. They also said to try putting in a dollars worth of Desiel before you put in a full tank. It is a good fuel system cleaner and prevents vapor lock in winter. Make sure you put in the Desiel first and then fill the tank completely to the top so that there is not too much Desiel to foul up your injectors. I have been doing this in my VW for all 4 years that I have owned it and it havs never done any damage. Starts in 2 cranks in -35C without pluging it in though!

 

[northyork]

Hrm... it would be hard to convince me that putting diesel into my baby would be a good thing. But hey, if it works for you great.

 

[Big Daddy]

They also said to try putting in a dollars worth of Desiel before you put in a full tank. It is a good fuel system cleaner and prevents vapor lock in winter. Make sure you put in the Desiel first and then fill the tank completely to the top so that there is not too much Desiel to foul up your injectors. I have been doing this in my VW for all 4 years that I have owned it and it havs never done any damage. Starts in 2 cranks in -35C without pluging it in though!

Vapor lock is usually a result of heat and high fuel pressures, it usually occurs in summer months not winter. However vapor lcck is a thing of the past: (Vapor lock is highly unlikely with today's fuel systems. Vapor lock occurs when the vapor pressure of the fuel is higher than the surrounding environment. In older engines with "sucking" fuel pumps at the engine the pressure in the fuel line to the tank was reduced by the sucking action of the fuel pump drawing fuel form a fuel tank nearly twenty feet away, and when heated, the gasoline actually boiled creating a vapor of gasoline which the fuel pump could not handle, thus the name "vapor lock". )

Diesel fuel gels in cold weather and I would not use it in a gasoline motor. They make fuel conditioners, such as Redline's SI-1 injector cleaner which manny BMW personnel recommend.

Just some thoughts.

 

[Average Jae]

i've been a huge proponent of the 93 octane gas. at least of using what is recommended. but recently i came back from a service appt, and found some interesting info. my car has an irratic idle during cold starts. my service rep told me to put in the regular stuff in the winter months, rather than the typical premium. it'll give smoother idle he says, i imagine due to the gas being little easier to break down or something, but who really knows.

well i guess i'll find out the next time i fill up, and report back on whether that myth proves true or not. he has an m3, and swears by the regular stuff. just a fyi incase you guys have some cold start issues.

 

[newguy]

Refineries blend gasoline somewhat differently for winter use. The RVP of gasoline is critical. This is Reid Vapor Pressure. It needs to be higher in the winter so the gasoline Vapours will ignite in cooler temps. This is usually done by adding more butane to the blend of gasoline. In the "summer" months, this spec us usually relaxed somewhat. Also, if you use gasoline with ethanol in it, you really do not have to add any gas line anti-freeze..I really wouldn't add diesel to gasoline under any circumstances...its too risky..it will coagulate in extreme cold, and gum up the works..

 

[epj3]

Wouldn't diesel fuel be like, putting 32 octane gas in your car? I know it's not quite the same, but still... In a sense you WANT diesel to ignite the same way pinging happens....sort of?

 

[geneo]

the dealer can see what rating of gas you, use but i never heard of any one paying that big of price, dont buy a mercedes

 

[Average Jae]

merc sounds better than audi. my friend's engine was under warranty but was busted .(advised by the service rep, to take for a spin.. he thought something was amiss.) within a mile from the dealership, his car just up and died! and the dealership claimed that my friend didn't get regular oil change. they were correct, if by oil change they mean, OIL CHANGE AT THE DEALERSHIP ONLY!! it was utter BS, and my friend had to drop a few grand to just get his car back, After his car was in the shop for 3 weeks for a collision repair.

after hearing something like that, i don't know if i'd go for an audi.. (even if i'm sure things like that happen w/ all the compaines, but a BS is a BS no matter what!)