DaveJ

Since I have no idea if the former owner of my CPO RX330 used premium or regular gas, I was wondering if I need to reset the computer before testing with either premium or regular. If so, is the easiest method to pull the battery cable for 30 minutes?

In addition, there are some people including my dealer that recommended alternating between regular and premium every other fill up. After reading many threads here I haven't noted many people using that strategy. Anyone here following that method?

Thanks.

dhamaka127

In my 04 RX 330, I just put in 91 or 93 octane. This one time this one guy in NJ put in 87... ( i was very pissed) ...i am saying this one guy because in NJ, you are not allowed to fill your own gas....well anyways....i saw a HUGE difference in mileage and mpg....and i didnt even get the same type of response that i get with the 91 or 93

I am saying 91 or 93 because if i dont find 91 (the octane level that the car is ment for) then i fill it up with 93.

My personal suggestion, I would just put in 91 or 93.....max 89...but that is still iffy with my perspective....you can check it out....with the mpg you get.....for me with 87 i got like 17 or 18 with about 75% hwy....normally i get about 23.5 with 91 or 93 octane....with 75% hwy.....

I hope this helps...good luck...

crosborne

I always use 87 octane and get between 23 and 24.5 mag hiway and 20-22 city. I tested higher octanes and saw no difference in MPG.

The last page of the manual even says "select 87 octane or higher."

DaveJ

Which model and year RX do have?

tfischer

DAVE:

The book calls for 91. What your dealer may have meant by alternating grades is that if you fill the tank with 93 and use half of it up, and then you fill it back up with 89, your tank of half-and-half has the octane of the average of the two, so now you have a full tank of 91. (That's how the stations mix it; they usually just have 2 large tanks underground which is mixed at the pump in different proportions.)

Since the stations here don't usually have 91, I alternate between 93 and something less (like 89), but I would never fill it up from near empty with something as low as 87. Should that happen for some reason, I would suggest burning off a quarter of a tank and then adding some 93 to get the octane rating on its way back to something the engine was designed for.

crosborne

2004 RX330 FWD.

If you feel better putting in higher octane then use it. Bottom line is that its your car and your money. Only higher compression motors need higher octane and its to prevent detonation (knocking).

Lexmex

I have thrown 116 octane racing gas in my RX300 once. The ECM picked it up pretty quickly. Was using it more to clean my system out, but no ill effects from the stuff. To get any effect on the track you need to advance timing primarily.