sleepybobcat

Quick poll: do you use regular or premium gas in your RX300?


I have used premium since day one... it now has
17000 miles after 10 months... premium gas
is usually 10 cents less at the local stations, so I
could have saved about $100...(10 cents times 1000
gallons @ 17MPG)

All the vehciles in my family requires premium, and
I had not noticed the RX300 only specified regular.
I only discovered this while looking in the owner's
manual for the first time recently....

Bob

MikeK

I have about 1900 miles on my RX and have experimented with both 92 and 87 octane gas. The 87 octane (mid-grade regular Chevron) actually produces better gas mileage and what appears (SOP) to be the same power.

mikey00

I currently have a 2001RX SS and previously a 2000RX. I use regular. Tried premium in both, but no advantage in gas mileage or performance.

malhokc

87 Octane is all that is recommended.

William Zimmer

My owners manual says 87 octane is fine but for improved performance use 91 octane. I compromise and use 89 mid-grade.

malhokc

The 2000 Owner's manual only makes statement on using at least 87 octane, does not mention 89 or 91, as fas as I can recall, will double check.

DIP_RX

I have been user 87 regular but stick to a decent brand
Mobil, Amoco, or Sunoco. I use 91 once in a while but don't notice any difference. 87 octaine has come down to $1.29 here in Jersey

quazi

I have found that mid grade 89 octane works the best.

Regular does not perform well, and I have noticed a slight decrease in gas mileage (16/22 mpg). But the real issue for me a regular is performance.

Premium performs very slightly better, but I get worse gas mileage when I use premium. (17/22 mpg.) That makes no sense, but it is what I have observed. I keep a log of every fill-up, so I know what I am talking about. Maybe I enjoy the performance of the 91 octane better ;-)

Mid grade provides me with about 20 mpg in town/23 highway and provides very good performance. For me, it is the best bang for the buck.

RXKen

91 will NOT give you any better performance in the RX-300, the car does not adjust performance based on the octane level of the gasoline. What it will do is retard the timing if the engine knocks on a low grade gasoline. If you aren't knocking on 87 octane placing 91 in your tank is a waste, the engine doesn't do anything differently (it doesn't advance timing if it finds higher octane).

If you it makes you feel better do it, but there isn't really any reason to if you don't experience engine knock.

ObiDon

The computer in the RX and most other vehicles run a constant test on the knocking or pinging that may occur. If you run higher octane you will get more performance because the computer will advance to a point of ping based on the fuel you are running. Premium all the way and it shows

RXKen

I disagree, according to Toyota, so I assume Lexus is the same, that the software merely checks for ping, if ping is present timing is retarted until ping stops, if ping isn't present, timing is not adjusted.

Real world driving will tell you that this is true, otherwise the computer would always be bumping up the timing to the point of detonation, meaning that as soon as I put the car under stress, say a large hill or stomping on the gas pedal that initially I will get some ping until the computer can compensate and that simply isn't true because the engine is not always adjusting itself to the limit of the octane.

I've had this discussion with a Toyota engineer so I am pretty certain that I am accurate, but if you have a better source that says otherwise let me know and we can dig deeper. An easy test would be to take your car into the shop and have them put it on the computer, run it 5 minutes on regular gas and note the timing settings, drain the gas, fill with premium and run another 5 minutes and note the timing settings, I bet you get the same results both times, at least according to Toyota, you should.

BTW, the engineer told me that the only way to reset the timing higher after it had been retarded was to reset the computer (pull battery cable for awhile I guess), then the computer would hunt again if it detected knock, otherwise if you've been running regular gas and knocking and it retarded timing, it won't "un=retard" it.

ObiDon

The computer does not let the engine ping, but to an approach of ping so you would not hear it. You are correct that the computer adjusts because of the quality of gas, but it works both ways.

RXKen

It's a moot point anyway, gas just jumped 30 cents a gallon this past week! Evidently some refinery in Chicago had a fire and so now gas prices in the midwest just got jacked...

MrSypher

I only use mobil 91 octane.... Because it makes me feel warm and bubblie on the inside...

TexRB

I use 87 octane with no problems. A higher octane is just wasting your $$ IMHO