Gas Question - Toyota Nation Forum : Toyota Car and Truck Forums

b0r1cha · 07-28-2008, 01:55 PM

So my mom has the Lexus Rx350. i tihnk the 07 model. anyways iw as wondering would it be THAT bad to put in 87 octane rather than 91?

workerant · 07-28-2008, 02:04 PM

It's GOOD to save $$$.

Unless the manual said the car need 91.

Mike Gerber · 07-28-2008, 02:37 PM

^ Exactly. GO with what the owner's manual says. If it says it requries 91 octane, it may ping on 87. If the manual states that 87 octane may be used, you have been wasting money on 91 octane.

Mike

geoff5093 · 07-28-2008, 02:45 PM

The reason it says it requires premium is because as Mike said, the car wrongs optimally on 91+ octane, and using lower rated octane may cause pinging/knocking. I'd bet though that since it's an '07 Lexus, they expect some people will use regular so it would probably knock down the timings to accommodate for the difference, but again that's just what I think.

TRD VVTi · 07-28-2008, 02:49 PM

Quote:

Originally Posted by Mike Gerber

^ Exactly. GO with what the owner's manual says. If it says it requries 91 octane, it may ping on 87. If the manual states that 87 octane may be used, you have been wasting money on 91 octane.

Mike

+1

You probably wouldn't hear it, but the computer would see it. Performance would suffer if the car's designed/programmed for the higher octane. Usually when performance/efficiency suffers, so does fuel economy.

b0r1cha · 07-28-2008, 05:53 PM

hmm ok i guess its best to just use 91 octane then. haha. just thought i would ask and see.

gdanaher · 07-28-2008, 05:54 PM

The manufacturers advertise a certain mpg rating, a certain horsepower and torque rating, and all of this is related to the octane rating of the fuel used in the tests. If they said openly that it was ok to operate with 87 octane instead of 91 then they would be stepping on their own toes with respect to mileage and performance, so they don't. But the car will in all probability run just fine, less a couple horsepower, and will not ping, knock, or cause other problems. It should run just fine.

Now, having said that, it IS possible to drop the octane rating down to the point of causing a knock. Some years ago I had to settle for a tank of Nova at the friendly Pemex station. They were out of anything above 76 octane, so Nova it was. Thought the valves were going to fall out until I got up the coast to Veracruz where I found much better fuel. They don't make Nova any more!!

geoff5093 · 07-28-2008, 08:34 PM

Quote:

Originally Posted by b0r1cha

hmm ok i guess its best to just use 91 octane then. haha. just thought i would ask and see.

Around here 91 octane is generally just 10 cents more per gallon then 87, so you are only looking at $1.5-$3 more for a fill up.

coolbeans · 07-28-2008, 08:53 PM

Lucky you... where i live its 91 is usually 20cents more, some times 25 cents more if ur really having a sh!ty day....

CamrySExxx · 07-28-2008, 09:46 PM

whats the owners manual say

b0r1cha · 07-29-2008, 01:03 AM

havent read the manual but on the gas cover thing it says premium fuel only. which i know i should follow, but i was just wondering about the downfalls of using 87 octane.