I have a 2010 RX 350 and use regular gas. I have tried premium gas and have notice no difference. Nothing. Nada.
Same gas mileage and same performance. I believe the computer reads the octane delay and adjusts accordingly.
And the octane level has nothing to due with crappy gas. I believe that is a very naive understanding of gasoline. Octane rating does't effect anything other than burn rate. The higher the octane the slower the fuel burns.
So I guess as long as we can be sure that using the 87 is not doing systemic damage to the engine, it seems reasonable to experiment to see what works best for you.
We run regular in our 11. Once I put premium into the tank and an espresso machine came out of the dash and made me a latte. : )
Seriously, one tank of premium gave us +1 MPG and not much else.
If running regular would muck up the engine, there probably would be an escape clause from the legal beagles in the terms of the warranty.
The days of a carburetor gumming up from varnish in the gas are over.
I think the premium recommendation is to keep people away from the new 15% ethanol gas.
Hope this helps.
Well it's been two years since I made the original post and I've been using the regular ever since. Saved a boatload of money and never had any problems.
Excellent! I read through this thread earlier today and wondered what the OP decided to do. Good for you BatmobileX for making the decision that best fits your needs. My wife runs 87 octane in her 2010 RX350 with absolutely no issues. I run premium in my SC because I drive it much harder than she will ever drive the RX. If I drove the RX as often and as hard as I drive the SC, I'd probably run premium in it too. I've ran premium in the RX in the past and can't tell any difference under normal driving conditions.
The 2010, 2011, 2012, 2013, 2014 engine is the same as in the Highlander and for the Highlander all those years the manual says regular. Lexus put the premium in the manual to make the owners feel special, but after the economic crisis hit in mid 2012 they changed the wording to "Regular" in order no to scare the now poor RX buyers.