rongro

I ran 87 octane in my hybrid for the last 8 months that I owned it. It ran fine and still got great gas mileage,25 - 27 mpg. No problems. I now have hte 2013 RX450h and I am using hi-test until the car breaks in at around 8K miles.

Cruiter

You do know don't you that 87 octane is recommended for the 2013. Just saying.....

rongro

87 octane may be rated for RX350, but not the 2013 RX450h. The dealer has advised me that I could use 87 instead of 91 or 93 and everything would be fine, but I would give up some performance. The owner's manual also indicates that performance could be affected by using a lower grade octane. I will be using 91 or 93 in the new car until I complete break-in (about 8 to 10K miles); and will continue to use the same on highway driving. I found that my 2008 RX400h ran well on 87, but used more gas at highway speeds.

Aptosuser

Having just acquired a 2010 RX450h (with only 15,000 on the odometer ), I wanted to know if I absolutely had to use premium gas. I hadn't even thought to check before I bought the car. Anyway, the service adviser at the dealership said to use premium, though I could use mid-grade if I wanted. But I see that the previous model, the RX400h, was rated for regular gas, per Consumer Reports. It looks like it has the same power plant as the RX450h. So does anybody know why the recommended gas grade changed?

Droid13

The RX400h uses a 3.3L engine, the RX450H uses a 3.5L engine. But, the most likely reason for the recommendation to change is the RX400H has a compression ratio of 10.8:1, whereas the RX450H has a compression ratio of 12.5:1.

12.5:1 compression ratio is pretty high and technically a no-brainer that premium gas would be a requirement. However, one thing to remember is the compression ratio is a simple mechanical ratio that does not take into account some unique aspects of the Atkinson cycle engines used in hybrids. Atkinson cycle engines actually reduce the amount of air drawn into the cylinder for efficiency purposes, so the actual pressure under compression is less than a conventional engine at the same compression ratio. This is a potential reason why some people find it satisfactory to run lower grades of fuel.

Aptosuser

Our other car is a 2012 Camry hybrid, which also has an Atkinson-cycle engine, but only a 2.5L four-banger. It takes regular gas. That's why I was wondering whether premium is really necessary for the Lexus. Of course, I'm sure the Camry's compression ratio is lower; I'd have to look it up.

The Camry is a great car by the way. My wife drives it and is averaging better than 41 miles/gallon after 20,000 miles. That makes up for the Lexus's lower mpg, I guess. I'll just have to go lighter on the accelerator to make up for the extra cost of premium fuel. Of course if I valued mpg over a smooth, comfortable ride, I would've bought a Prius v.

Craig123

We have run 87 since we have owned our RX450h. When we ran a few consecutive tankfuls of 91, we were amazed that the gas milage actually dropped. You are correct with respect that the computer adjusts. There has been no noticeable difference in power in our experience. What do you think this vehicle is, a high compression muscle car?

Aptosuser

A Volvo service adviser once told me that our '00 S70 GLT could adjust to regular gas, despite Volvo's recommendation to use at least 89 octane. The adviser at the Lexus dealer where we bought our '10 RX450h eight days ago said we should use premium, or mid-grade at least. I'm still on the first tank of gas. I don't know what they filled it up with. But based on your report, I'll go for 87 and see how the car likes it.

Craig123

Just Google "Bill Wattenburg and gas octane levels". He use to be on the radio in the evenings prior to KGO switching their format here in the SF Bay area. Once I heard his reasoning for the lower octane fuels, there was a switch in our gas usage at the pumps. We never looked back.

falconer

8-10 K for breakin? Dealer told me 1,000 miles for our 2014 450H. I dont recall that the owners manual said the break in is that duration.

marcarl

I have never put anything but 87 in my 2012 450. 35,000 miles and no problem.

camcon007

My brother is a mechanic at the local Lexus dealership and he said that you can put 87 octane gas in any of their cars, however he suggests that once every 4-5 fill-ups an octane booster is added to clean out the fuel injector. Does this save money in the long run??? I don't know since the octane boosters are anywhere from $3 to $5

Aptosuser

My understanding is that all gasoline has detergent additives which are required by federal law. Major brands like Chevron and Union 76 advertise that their detergents are better than others and this article at AutoGuide.com backs them up. Chevron, Union and a number of other brands are rated as "top-tier" gasolines, meaning that their products are engineered to a higher standard than other gas brands that only meet federal EPA minimum requirements. Per AutoGuide.com, for a company's gasoline to meet this standard it must "... pass four tests – deposit control on intake valves, fuel injectors and combustion chambers. Beyond that it must also prevent intake-valve sticking. Basically it’s gas with extra cleaning agents designed to keep engines running their best." Moreover, a company must use the same additives in all grades of gas to keep its top-tier rating. So even if you use nothing but 87-octane fuel, as long as you consistently fill up with a top-tier gas you shouldn't need an octane booster to keep your fuel injectors clean. (While these higher rated brands will clean your engine better than other gasolines, they won't deliver better mileage than cheaper brands.)

cflutist

Newbie here (purchased in SF Bay Area on 1/7/2014).

According to Gas Buddy, Reg (87) is $3.37 and Premium (91) is $3.57 / gal at my local Costco.
So for 17.2 gals that is an extra $3.44 for Premium or $3.30 if you consider the 4% cashback on my Costco Business AMEX card.

So I read the manual and it says to use Premium from "top tier" gas stations.
Will I be harming my RX450h engine by using Costco gas?
Or should I buy Chevron at $3.85 per gallon for Premium.
If I could get away with 87, I would too (but don't want to do anything stupid).

Any other suggestions?

Still trying to read through all of the manuals and so I don't have a clue right now what my mpg is. I do know that being retired, most of my milage will be city driving which is why I got the Hybrid in the first place (past history shows that I drive only 4K miles per year).

Thanks in advance.

Cheryl (2014 RX 450h AWD)

kitlz

Welcome to CL, Cheryl. I do mostly city driving and relatively short commutes too. Fill up twice a month with half a tank left. I've stuck with Shell V-Power (93 octane, NJ doesn't have 91) for the past 4 years. Over the weekend I paid $3.99 which included a $.10 premium per gallon for using a credit card. Yeah, I know but I don't like to carry cash. Plus a credit card is replaceable, cash isn't I don't have any personal experience with Costco gas. Have you used them in the past with positive results? I understand their brand has additives. It probably won't hurt to give them a try. But I'd stick with premium. The cost difference is really negligible with the amount of miles you drive a year.