87 Octane?

[smyrnagc]

Just wanted to get some feedback on what octane you guys are running in your RX 300's? Since we bought it we have been using 87 octane but I saw in the manual that it recommended a higher octane. What has been your experience?

THanks, Hal

Nashville

[Grumpa72]

What does your owner's manual say is the minimum octane? This info may also be on the fuel filler door. I have an older Acura Legend, 2007 BMW 328xi, and a 2005 RX 330. All three say that premium is recommended "for maximum performance or power", or some phrase that implies the same thing. They also go on to give the minimum octane for each car. That said, I run the regular 87/89 octane, whatever the minimum is for that station, in each car. No problemo!

Fuel injected cars typically have a knock sensor that listens for knock in our engines. If you are demanding too much from your engine or the fuel isn't of sufficient octane, then the knock sensor detunes the engine slightly until the knock goes away.

You can test your car by letting the fuel tank get low and then adding 1/2 tank of the fuel. Drive it in your normal situation and see what happens. From what I read, very few cars have such a high performance engine that they will absolutely need premium. Imo, using premium guarantees maximum horsepower, which gives the manufacturer bragging rights for their TV ads - you have seen the ads where they claim X horsepower and often say that it is better than the competition.

[wwest]

Just wanted to get some feedback on what octane you guys are running in your RX 300's? Since we bought it we have been using 87 octane but I saw in the manual that it recommended a higher octane. What has been your experience?

THanks, Hal

Nashville

I've been fueling my '01 AWD RX300 with nothing but regular from the very beginning, purchased new and now with ~70,000 miles

No adverse affects.

[mccldwll]

Just wanted to get some feedback on what octane you guys are running in your RX 300's? Since we bought it we have been using 87 octane but I saw in the manual that it recommended a higher octane. What has been your experience?

THanks, Hal

Nashville

I've been fueling my '01 AWD RX300 with nothing but regular from the very beginning, purchased new and now with ~70,000 miles

No adverse affects.

wwest knows far more about this than I do, but I do have a question/concern about running octane too much lower than recommended. Yes, the knock sensors (more than one, I believe someone said, I don't really know) do adjust engine timing to handle it, but I've heard about some people experiencing premature failure of these sensors, and they are pricey. I have no idea to what extent there may or may not be a causal connection, but it would make sense that the more that's demanded of a sensor, the faster the wear. And for Lexus it's a win/win--set engine for higher octane, advertise higher horsepower. recommend higher octane, sell you a new part/service if you don't adhere to advice. And if the sensor doesn't take care of it, the pinging may have longer term consequences. Not saying use premium, but might want to use 89. 2-3% cost increase might be worth it. Again, I don't know the answer, but I do hedge my bets.

[mikey00]

Both my 2000RX and now my 2001RX use regular. I did experiment a little with higher octane to see if there was any benefit and there wasn't. My 01 is now at 130,000 miles. I have never had a valid check engine light or any sensor failure and the plugs looked new when changed at 125,000. If you find better performance with higher octane it is only because your wallet is lighter.

Some older RXs may benefit from a higher octane if they have a lot of carbon buildup due to many short trips,etc. or maybe you bought it used and are not sure of it's past use. In this case I would be more inclined to investigate carbon removal products before going to a steady diet of preimum.

There has been at lot of discussion about fuel requirements in the past. Do a search on "octane" in this forum for info. Even a survey at this link:

http://www.clublexus.com/forums/showthread...ighlight=octane

[KBRX330]

My 2004 RX330 has never seen anything other than Shell or Marathon or Sunoco 87 in 143,000 miles. Never a CEL and the spark plugs went to 140k. However, I do use techron or redline s-1 fuel systems cleaner every 20,000 miles to prevent deposit build up. When I disassembled the throttle body at 140k for cleaning it was still fairly clean.