Frayzn

I just purchased an 08 RX 350. I filled up for the first time yesterday for $55.00 using their 93+. Had I filled up with 87, it would have cost $52.43. I think I'll pay the extra $2.57 to prevent any problems. I just don't think it's worth the risk for that little money. Granted, I know it will add up, but so does running cleaner. It all comes out in the wash IMHO.

That's just my $0.02

JLeffler

I guess I meant mid-grade. I see your point. When I drive to Arizona it would be 87 too, but the cheaper gas. Makes sense....and $200 isn't that bad when you put it that way. Thanks for the help. Don't want to hurt the new baby to save a couple hundred.

JLeffler

93? We don't even have that available. $2.57 hardly seems an issue even over time. Good to know!

takeshi74

AS RX330inFL stated, altitude acts as an anti knock agent. You can try 85 and see how it goes. You'll know if you get knocking. If you want to play it safe then stick with 87.

Depends on the RX. Our 400h is designed for 91 though there are certainly those that have run lower octane in the 400h without adverse effects.

JLeffler

I think I'll play it safe. Worth the extra few cents!

lexus114

It`s only something like $3.00 and some change more per tank. Is it really that much of a deal breaker??

JLeffler

Nope! For some reason, I'm bad at math and didn't look at it that way. So much enjoying this car right now, that cost is so negligible.

RX330inFL

If your circumstances were different I might have said for you to go with the lowest grade of fuel available if you wanted to do so. Without any hard data from Toyota/Lexus to rely on the next thing to go with is to look at the facts you do have. In your case living in or near Denver is an important piece of data. No matter where you go you will be going up and down hills and some can be substantial. You are also more likely to have a family, meaning your vehicle will be loaded with people and things on a regular basis. Those alone would give me pause and think about using a fuel grade or two higher than regular unleaded regardless of price. The fact that when you work the numbers it is not really all that much extra makes it an easier decision.

Personally, down here in Flatland, FL I run 87 octane regular unleaded for my day-to-day driving needs in my RX330. Not much of a strain on the vehicle going up and down hills as there are few, the vehicle is rarely carrying much of a load and I am not in a hurry to get any place in particular. I have seen little change in MPG when I dropped from premium to regular fuel. However, when I load up for trips it is not unusual for me to put in 89 or 93 octane (we do not have 91 octane in this area) as the RX is fully loaded and I will be going up and down in elevations of notice. There is more strain on the engine and having that little bit of extra kick comes in handy.

As for the price of fuel, one might save more by checking sites like gasbuddy.com or to download their app to your smartphone to see what is available in your area.

chimera

The 87 octane is just fine. The higher octane rated fuels are ideal for higher compression engines (the higher the octane rating, the more compression the fuel can take without ignition). If you are not getting engine knock (pre-ignition) with 87 octane, that is the fuel to use.

lexus114

10.8:1 is a pretty high compression ratio for a street motor. That is the comp. ratio of the 3.3L

JLeffler

I have a new stalker You hit the nail on the head on all fronts. Live just outside of Denver in a very hilly area (we call them mountains here!) and it's my family that rides around all day. thanks for the tips and yes, I do use Gasbuddy....it's amazing the range of gas prices in town. Even the cheap of the cheap, there can be an 85 cent difference from one place to the other.

RX3302004

I would go with the lowest octane recommended in the manual. There's no reason to go over that for me. It's not a performance car and the lower grade gas has the additives to keep it working.

Frayzn

This thread provided an itch of curiosity. I mentioned before what the difference in price would be between 93+ and 87. I've quoted it below to refresh your memory.

I had to drive to St. Louis a few days ago and I took the RX. I started on empty and filled up with 87 at my local Shell station. I put in 14.8 gallons at $3.399. This was a total of $50.31 price paid. On the trip there, there was a small crosswind over I-70, blowing at about 5 kn to from southwest to northeast. I was traveling West. The total trip was 268 miles. I used 14.1 gallons, averaging 19 MPG.

Driving around the city, I used most of the gasoline in the tank. I filled up again, at a Shell, right before I left to head home. This time I put in 93+ fuel. I put in 15 gallons at $3.52. This was a total of $52.80. On the drive home, there was a stiffer crosswind, blowing at roughly at 8 kn North to South. I was heading East. Driving the same route home, the trip was 268 miles. I used 11.55 gallons, averaging 23.2 MPG.

This is where the math gets interesting, so bare with me.

Trip to St. Louis from Indianapolis
Distance: 268 Miles
Fuel: Shell 87 @ $3.399
Fuel Used: 14.1G
MPG: 19

Total Cost: (14.1G @ $3.399) $47.93

Trip from St. Louis back to Indianapolis
Distance: 268 Miles
Fuel: Shell 93+ V-Power @ $3.529
Fuel Used: 11.55G
MPG: 23.2

Total Cost: (11.55G @ $3.529) $40.76

Analysis
Total Cost at Pump
Regular: $50.31
Premium: $52.80

Total Savings Using Regular: $2.49

Total Fuel Costs for Trip
Regular: $47.93
Premium: $40.76

Total Savings Using Premium: $7.17

Total Net Savings Using Premium: $4.68

I think this speaks for itself. Premium fuel runs cleaner, yields higher performance, is recommended for your engine, and saves you money in the long term. Don't pinch pennies at the pump, because you'll spend more in the end.

Though to thoroughly prove this, more testing would need to be done; however, the wind was even in favor of the regular (87 Octane) gasoline. This is proof enough for me. I hope this wasn't a waste of time to read for you.

RX330inFL

The concern from the OP is that while in most locations in the US we have a fuel selection at the pumps of 87/89/91 or 87/89/93 octanes, when you are told to use regular unleaded you know to select 87 octane. However, in regions of Colorado the octane selections at the pump are 85/87/89 due to high elevation. Now, do you run 85 octane as that is regular unleaded there?

Turns out that if you go by the Owner's Manual, which was my recommendation, you end up using the mid-grade fuel in that area which of course is more expensive than unleaded regular.

RX330inFL

No need to stalk. I spent some time at the Academy. Only a few real metros in the state. If you asked someone on the street in any place other than CO to name a city in CO you would more than likely get Denver as your answer and not Vail, Colorado Springs, or Fort Collins. You could do the same for most any individual in most any state and have good odds to be right.

As for Flatland, FL... my old office complex was at 6ft above sea level while I live up in the hills where I am at 95ft of elevation. Plenty of oxygen down here.