Eddo

Is there a potential for damage to the engine by using 87 octane gasolene in a 2008 RX-350?

Eddo

To answer my own question, Page 439 of my 2008 RX-350 manual states that I can use fuel with an octane rating as low as 87 (Research Octane Number 91). The manual goes on to say, "You may occasionally notice light knocking for a short time while accelerating or driving uphill. This is normal and there is no need for concern."

xfirechief

Anytime there is knocking in the engine it is of concern. That is basically pre-ignition & is a hot spot issue. If it gets too bad could burn a piston or worp a valve. I have been using the midgrade with NO KNOCKING at all.

lexus114

Well,the slight pinging going up hill etc.is not suppose to be bad.That is when you supposedly get your best fuel millage too.

SugarRush

You mean down hill --> best fuel economy perhaps? I just find those 2 statements contradict them selves.

lexus114

That is what I learned when I worked for GM. Wether they were blowing smoke up my you know what,is another story.They claimed that when you hear that slight ping,every thing is adjusted properly.Meaning ignition timing,air/fuel ratio etc.is all @ the proper settings.

harleydjce

There are a number of other threads on this topic. Suggest you try the search facility under octane rating.

Mods - Can we make a sticky out of the largest thread on this subject?

biff44

If you drove like my little old mom, and stayed on the flat lands, you will be ok.

If you drove like me, you would be foolish to not use at least 89!

Boognish

Not this again! lol

lexus114

I know,this always comes up.

catdaddylo

Just got the latest Consumer Report magazine and they have an article on regular vs premium gas. The bottom line is if Premium gas is suggested by your owners manual you can use regular 87 octane but if your manual states Premium gas is required than you better use premium 91 or 93 octane. This is due to engines with higher compression. My Z3 has a compression of 10.5:1 and requires premium.The RX350 engine is 10.8:1 thus it requires premium. I alternate between 93 and 89 octane when my fuel gage is at the halfway mark, trying to keep a 91 octane blend. No problems and great gas milage 26 mpg highway @ 73 mph.

CK6Speed

iTrader: (1)

Most modern cars that require or recommend premium fuel can run safely on lower octane gas because they are equipped with anti knock sensors that detect knocking and will adjust ignition timing accordingly. As it retards ignition timing if needed, you will have a reduction in performance though. It may or may not be noticeable to the owner. By the way, this is in the owners manual, but the systems have been around for decades in most luxury cars.

Joeb427

iTrader: (1)

89 here on an '09 without any problems.

jfelbab

I use premium in my RX and I do this for three reasons.

1. The owners manual recommends it.
2. I get better performance and mileage (+ 1-2 mpg) when I use premium.
3. My car stinks of rotten eggs every time I have used 87 octane fuel. (Yes, I've had the car back to the dealer to verify it is tuned and operating properly.)

It only costs me, on average, $2.50 more per tankful to put premium in the tank. This is still true today with gas at $4.00 a gallon. You could say that premium is a better value today than it was 10 years ago when gas was selling for $1.10(87 octane) - $1.30(91 octane) per gallon.

When I use premium I have a car that performs perceptively better and no longer stinks. I also burn real gasoline and not that 10% Ethanol crap which gives me another 1-2 mpg. I consider myself lucky to live outside the mandated area for E10 fuel.

Using real gas (non Ethanol) and mostly premium I have averaged 22.1 MPG over 40,000 miles of combined 40/60 (city/highway) driving in my RX.
MIN MPG 17.2
MAX MPG 27.2
AVG MPG 22.1

What you choose to burn in your RX is your choice. I've made my decision on what to burn and these were the reasons for my choice.

CK6Speed

iTrader: (1)

You are lucky your area doesn't used E10. I too used to get at least 22 MPG bone stock before E10 was mandated. Even with my 20" rims the lowest I used to get was 20 MPG. As soon as E10 came along it dropped to 18 MPG over night.