Its my dads commuter car, and he wants to know what the lowest octane he can put in there is. I know it asks for 91 or premium but he's not racing it, and i think its only 10:1 compression or so, do you think he could get away with 87 or 89. If they have stereo knock sensors it will just retard the timing and he wont have issues... if not, he should stay with 91 correct?


oh yeah, its a 93 mint condition with 103,000 miles on it.

 

All Lexus engines call for premium fuel, 91 octane is a midgrade, use what it calls for and prevent possible problems down the road, my .02.

 

Here's a strange story... I went to the gas station last week (a full service one) & went inside to make a purchase & also to pay for the gas, Guy charges my card for both gas & purchase.. Then I get outside & tell the attendant to fill my car I tell him 93...he says he's out..? Damn.. Ok 91... out of that too.. DAMN....What DO you HAVE? ..he says 87.. DAAAAAMMNN.. I said "whatever" as I was in too much of a hurry to go back inside & have my debit card credited back,etc..

Here's the Point This was my 1st time using a less than 93 grade gas in my car..and let me tell you.. it "seemed" to acelerate smoother, pick up faster, and overall just "drive better" ..Don't ask me how or why? it could have been psychological, but then I would have expected the Opposite, so I'm ruling out that...anyway just figured I'd share... it ended up being the best gas of my life go figure..??

But under normal circumstances I always use the mfgr's recommendation.. Good luck

 

the 87 would have burned cleaner and more complete as well. Before you guys do smog checks in your car you should go in with 87 or 89 in the tank, especially if you are running aftermarket cats. I wouldnt be surprised if what you were feeling was more power due to a better burn. Alot of new cars automatically adjust for lower grade gas, knock sensors retard the timing. And bring it back up when you put better gas in as well.

 

A local TV station here in the Dallas/Fort Worth area recently followed a state fuel tester making his round at a local gas station. The TV station reported that the 87 octane tested at 89+ octane, the 91 at 93, and I believe that the 93 tested at 95 or 96 octane. I didn't get the name of the gas station, but the interior decor looked like 7-11. Also, there was no comment as to how common it was for the actual octane rating to be substantially higher than advertised. So, maybe you put 89+ and your car adeptly handled it.

 

Hmm..interesting..Coulda' have been.. Either way I was Pleasantly suprised

 

the higher the octane rating actually means the more resistant it is to ignite. so when you used an 87 grade octane it actually burned faster, i dont know about cleaner though. i have pumped all: regular, plus, and premium and i can tell that premium last longer but the cost might out weight the benefit now. especially since now the price in the states are high, i might consider going with plus from now on.

BTW my friend's dad works quality control for an insurance company that insures gasoline companies. he told me that there all the same, gas grades that is. his dad told me that per 1000gal. of gas they add an additive that is the amount of one of those ozarka drinking water bottles. I also have another friend that goes to SMU and one of his professors used to work for exxon or chevron (chemical engineer) and he told me and my friend that gas is all the same very minute difference.

people believe what they want to believe, i have always followed the strick rule of using premium even after i heard all of this. this was a good 2yrs ago but hell im wasting money if it is true.

 

pTown, under most circumstances, our engines don't even "use" all of the octane available. Only under high load conditions such as WOT does the knock resistance of the higher octane become a factor. You are correct that the knock sensors in conjunction with the engine CPU will appropriately retard the timing in those conditions. They are also extremely fast in doing so, to the extent that the driver will never detect knock, but will just be missing those last few lb-ft and hp.........

 

Jusy my own .02 too, but really makes more sense, as I see it, to use 93 in the first place...especially if the engine is still under warranty. It's not just a matter of octane and price......though it varies by brand, hi-test usually has a better detergent package than lower-grades. ( I like Chevron Techroline and the Mobil packages myself ). Yes, you'll save a little money up front with 87 octane, ( or cut-rate brands ) , but you may not really save much, if any, in the long run because you'll have to keep dumping cans of BG44K or GUMOUT in the fuel system just to keep the injectors and lines clean, and to get any water out. So why not just use a good gas with a good detergent package to start with, and not have to worry about crud and water building up inthe system? You often can save a little by gassing up on weekends...many stations drop their prices then.