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Luxury Performance Sedans

10006 messages,  Last post on Nov 26, 2009 at 6:59 AM

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What is this discussion about? Lexus GS 430, Acura RL, BMW 5 Series, Volvo S80, Audi A6, Infiniti M35, Infiniti M45, Mercedes-Benz E-Class, Cadillac STS, Sedan

#7875 of 10006 Re: M35 [sfcharlie] by markcincinnati Jul 24, 2006 (10:24 am)
Replying to: sfcharlie (Jul 24, 2006 10:04 am) I believe in this case the word is intended to mean REQUIRED.
#7876 of 10006 Re: Sudden Acceleration [shipo] by james27 Jul 24, 2006 (10:38 am)
Replying to: shipo (Jul 23, 2006 11:31 am) My last car was an Audi A6 with the 2.8L engine. It would run on regular or mid-grade, but felt like there was a potato stuck in the tailpipe. The computer would retard the timing so much to prevent ping that the thing had a much harder time getting out if its own way.   The current car, an Infiniti M35x feels free reving and nearly effortless if using premium, but loses maybe as much as 40-50 HP if you use regular. It will run, won't ping, but it won't accellerate with the abandon that it does running premium. So, depending on how much flexibility the engine management system has, how much power you started with, and your driving habits, you may not notice a difference. if you are perceptive and don't drive like a little old lady, you will probably notice.   If the engine management system cannot compensate for the diverse octane levels, and you dont' put at least the minimum it was required to run with, you will experience pre-combustion and damage the valves and or pistons. This is more prevalent at higher speeds and under higher loads (well, basically the same thing, as you load it with the higher speed, but a hill or mountain pass could make it worse). You don't have to hear it to have it make damage.   As an engine ages, if it is not treated well, it can accumulate carbon deposits. These can increase the compression ratio and turn a car that would run fine on regular into one that requires mid or premium to prevent pinging. Normally, though, the check engine lamp would have come on way before that was a symptom. Replies to this message: markcincinnati (Jul 24, 2006 12:42 pm) sfcharlie (Jul 24, 2006 1:22 pm) shipo (Jul 24, 2006 2:24 pm) markcincinnati (Jul 24, 2006 4:36 pm) warthog (Jul 24, 2006 2:39 pm) james27 (Jul 24, 2006 3:00 pm)
#7877 of 10006 Re: Sudden Acceleration [james27] by markcincinnati Jul 24, 2006 (12:42 pm)
Replying to: james27 (Jul 24, 2006 10:38 am) I have had several Audi 2.8 equipped cars none of them were allowed to run on anything less than Premium.   The fact that the computer attempted to save the engine from internal damage via retardging the spark may well have been the case -- but even my 1982 Audi 100S with the 2.8 V6 REQUIRED 91 octane.   The 1999 A6 w the 200HP 2.8L V6 also required Premium.   The compensation offered by the EMC was INTENDED to allow the temporary use of regular when no premium was available.   I called my Infiniti dealer (I say mine as if), and they told me I could USE less than premium in the M35 -- but that the engine did indeed REQUIRE premium and that the mere retarding of the spark was to allow you to get to the next station where Premium was available.   I assume these are true statements.   My wife's BMW, too, REQUIRES premium -- I just need to see if the words imprinted are recommended or the stronger requires.   The truth of the matter is that these cars will run on less than premium but with some long term risks should you run them on regular or plus over the long term.   Thanks to those who commented about mid grade -- I have, to this day, never seen a car that said MID GRADE was the design point of the engine.   I always wondered.   My 3.2 MUST have 91 (as did my 2.8 and 2.7T and 4.2) and it achieves maximum performance with 93 (I wonder if any higher, were it to be available at the retail level, would be of any benefit?)   Most cars that require regular will run just fine on mid and premium but it is a waste of money to do so.   I would NOT use premium if I didn't have to -- but on a twenty gallon tank the difference is, at most $4. Seems, in the overall scheme of things a small price to pay. Replies to this message: sfcharlie (Jul 24, 2006 1:22 pm) shipo (Jul 24, 2006 2:24 pm) markcincinnati (Jul 24, 2006 4:36 pm) warthog (Jul 24, 2006 2:39 pm) james27 (Jul 24, 2006 3:00 pm)
#7878 of 10006 Re: Gas required [markcincinnati] by sfcharlie Jul 24, 2006 (1:22 pm)
Replying to: markcincinnati (Jul 24, 2006 12:42 pm) This is an old message (#4224 from Aug 18, 2005) on the Infiniti M35/M45 2006+ forum:   The engine in the M35 is almost identical to that found in the G35 and FX35. Both can run on regular. I agree, however, that the V8 should be fed premium (335 hp) and to realize optimum fuel economy premium should be used.    The V6 can run quite well on regular. Infiniti only "recommends" premium in the V6.    As with any grade of gasoline, if you hear the slightest knocking noise from the engine, first try another brand of gas, and if that doesn't work, move up one grade to mid-grade.    Hope this helps   Apparently, not true?   If "Premium is recommended for maximum performance" is intended to mean "Premium is recommended if you want you car to go faster than a bicycle and if you don't want to wreck the engine" it's quite a euphemistic, if not intentionally misleading, statement from Infiniti.
#7879 of 10006 Octane question -- addendum by sfcharlie Jul 24, 2006 (1:57 pm)
Just to illustrate how varied the thinking is about this, I'm quoting a post from "http://www2.freshalloy.com/showthread.php?t=152476" which is not about the same car, but addresses the same issue:   For the first 3 years of ownership of my 03 6MT sedan I put nothing but premium gas in the car, mostly due to Nissan's recommendation for highest performance. Just for reference, 03-04 sedans with the 260HP rated motor are speced to run regular and IIRC all other G35 models do not allow the use of regular on a full time basis. With the 100% change in gas prices since I bought I car in early 03, and an almost doubling of my daily commuting distance, I decided to do a test and run 87 octane for a while. I've been running it for a couple of months now looking for a change in mpg, pinging, reduction in performance etc. So far, I've been pleased to find that I have had no measureable change in mpg, no pinging even under heavy load (uphill, low gear,AC, 100 degree temp, WOT), and no seat of the pants noticeable degradation in performance. While the rest of traffic slows down from 75 to 70 to 65 while climbing a long grade on the highway on the way to work the G35 still climbs without even quarter throttle in top gear while keeping the inside at 68 while the road cooks at over 90. If I took it to the track maybe a performance difference could be measured, but it still pulls strongly everywhere in the rev range and delivers the same smiles per gallon that it always has. My local dealer has a small fleet of 04X cars and puts nothing but regular in them. I had one with 40k on it the other week, it ran perfect, you know those loaner cars get hammered daily, and get fed the worst possible gas. If you have an 03 or 04 sedan, give it a shot. May take just a bit of the sting out of the gas price increases. Replies to this message: lexusguy (Jul 24, 2006 2:19 pm)
#7880 of 10006 Re: Octane question -- addendum [sfcharlie] by lexusguy Jul 24, 2006 (2:19 pm)
Replying to: sfcharlie (Jul 24, 2006 1:57 pm) Those older Gs had engines pretty close to the VQ35s in Nissan products that are spec to run on regular. I don't think running a current 298hp G35 on regular would be a good idea.   I'm sure our RX300 can run on regular, as it basically has a Camry engine. However, my wife puts midgrade into it because she thinks it runs a bit smoother. I always use premium in the LS430. Probably not absolutely necessary, but considering the amount of miles I put on it, I'm not going to take chances to save a few bucks here and there.   I definitely wouldnt even think of trying to use 87 in the XKR.
#7881 of 10006 Re: Sudden Acceleration [markcincinnati] by shipo Jul 24, 2006 (2:24 pm)
Replying to: markcincinnati (Jul 24, 2006 12:42 pm) The fact that the computer attempted to save the engine from internal damage via retardging the spark may well have been the case -- but even my 1982 Audi 100S with the 2.8 V6 REQUIRED 91 octane."   Mark, that must have been some rare car (as in one made in entire world). I bet you wish you still had it.   Best Regards, Shipo Replies to this message: markcincinnati (Jul 24, 2006 4:36 pm)
#7882 of 10006 Re: Octane by warthog Jul 24, 2006 (2:39 pm)
Replying to: markcincinnati (Jul 24, 2006 12:42 pm) A related question: Have you ever seen a street car that required more than 91? In North Carolina, premium is routinely 93; mid-grade is 89, and regular is 87. In other states, premium seems to usually be 91.    Anyone know why. Replies to this message: james27 (Jul 24, 2006 3:00 pm)
#7883 of 10006 Re: Octane [warthog] by james27 Jul 24, 2006 (3:00 pm)
Replying to: warthog (Jul 24, 2006 2:39 pm) Go up into the high mountain areas, say Santa Fe, NM which is somewhere around 7500' or so, depending on where you are in the city, and see what the octane levels are. The altitude limits the amount of air you can stuff into the engine (unless you have a supercharger or turbo), so they won't ping on the lower octane. Couse, they don't have the same power, either. Prior to electronic fuel injection, cars just didn't run well up there without adjusting the carburator, either. Most cars are power rated at sea level. They can make significantly less at altitude, regardless of that the computer does.
#7884 of 10006 Re: A Premium experience. . . [markcincinnati] by james27 Jul 24, 2006 (3:36 pm)
Replying to: markcincinnati (Jul 24, 2006 6:45 am) This is a quote from the Infiniti owner's manual, page 9-3 Printing March 2005, number OM6E-0Y50U0 (I might have the o and 0's mixed up - hard to tell) for the M-series, 2006 model year:   VK45DE engine In order to maintain engine and exhaust system durability and performance, unleaded premium gasoline with an octane rating of at least 91AKI number must be used."   It goes on to say in an emergency, use 87 to get you to the next gas staion with the minimum amount of 87 you can get by with and to avoid full throttle accelerations and abrupt acceleration.   FOr the VQ35DE engine   "Use unleaded regular gasoline with an octane rating of at least 87 AKI number.   For improved vehicle performance, INFINIT recommends the use of unleaded premium gasoline with an octane rating of at least 91 AKI number."   So, The V-8 REQUIRES premium, the V-6 RECOMMENDS premium. I can tell you from personal experience that I notice the difference in merging on the interstates around here where they are often going at 80-85. With premium, it just goes, with regular, you have to plan ahead (not much, but more). I think it idles smoother with premium.   I no longer have the Audi, so I can't look up their recommendations, but seem to remember it being almost exactly the same as Infiniti's is for the V-6.

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