rfcbuf Posted November 10, 2011 Share Posted November 10, 2011 Following the owners manual I use regular gas (87 octane) in my 2004 RX 330 with no problems. Mileage is always in the 19-20 MPG range. Newer (2009) RX 350 owners manual recommends 91 octain gas. Is 91 octain really necessary with the RX 350 engine and what would be the negative result of using 87 octain in the either the 330 or the 350 engine? I pose this question because my daughter has just purchased a 2009 RX 350. Quote Link to comment Share on other sites More sharing options...
jaswood Posted November 10, 2011 Share Posted November 10, 2011 Following the owners manual I use regular gas (87 octane) in my 2004 RX 330 with no problems. Mileage is always in the 19-20 MPG range. Newer (2009) RX 350 owners manual recommends 91 octain gas. Is 91 octain really necessary with the RX 350 engine and what would be the negative result of using 87 octain in the either the 330 or the 350 engine? I pose this question because my daughter has just purchased a 2009 RX 350. No negative results other than the loss of few PEAK HP. Engine/transaxle ECU simply enriches the mixture slightly if low octane results in detonation occuring under load. Quote Link to comment Share on other sites More sharing options...
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