I would possible use 87 octane on a long highway trip but I feel that 93 octane gives me better acceleration around town. I only drive around 5K miles a year, so using Premium gas is not going to ruin my finances...

 

That's just the mileage running 87 octane in my '01. I've run 87 in my 1990, 1995 and 2006 LS's, and adding up all of those miles without any ignition / combustion issue ever (even on an occasional full open throttle), the miles add up to somewhere near 650K+ miles across all 4 LS engines. Knock sensors manage timing to avoid any engine knock. Never had to replace a knock sensor, so it's not like the sensors are working more or harder with 87 octane. It's really a matter of personal choice IMO. With gas so much cheaper, the savings isn't that much, but I wasn't running 87 octane over the last 20 years for the savings anyway. My gas mileage is mid-20's at 75 mph A/C "on", near sea level, no headwinds, Michelin MXV4s at 35 psi. (Note: as your tires wear, gas mileage increases too due to less traction / friction on the road surface. This may not hold true for the new Michelin Premier though.) 87 octane starts the LS quite well in the driveway at -10* F.

 

Don't keep us in suspense ... why WERE you running 87 then?

 

For me regular versus premium it is really not a budget issue since I drive 6-8 k miles a year. I'm just an old geezer that does not like to waste money so I was interested in running the experiment when I had opportunity to drive 2k miles in a couple of weeks.

I have been using only Premium for about 20 years in cars that were recommended premium use (LS430 and Acura RL) and may likely continue to do so because I drive so few miles on a normal yearly basis, unless I am doing a long road trip when I will definitely use regular.

 

In my experience, the octane rating makes little difference in mpg, but rather the ethanol blend. And since my local stations sell ethanol-free premium gas about the same price as regular "pure gas", I just go for premium. Now, I have had no choice before but to fill up with regular octane gas with a 10-15% ethanol blend, and saw a significant drop in mpg. So my conclusion: ethanol sucks

 

Simple, because the engines run just fine without 91 or 93 octane. Back in the day before computer-controlled (variable) both crank and camshaft (valve) timing, I had to run 93 octane on my high-performance big block muscle cars, occasionally adding Steed or similar octane boosters to prevent knock, since combustion and timing could only be "controlled" with a fixed crank timing setting (ex. 12* BTDC). Sure there would be spark advance from the distributor, but it was often too much and caused low octane engine knock. If you're interested, do some independent research on the topic to find a thorough explanation.

 

I understand all of that ... but that still doesn't answer WHY you were running 87 all this time. Given that it doesn't matter whether you run 87, 91 or 93 why'd you choose 87? Because it was cheaper than 91 and 93, maybe?
FYI - I've run 87 on my 03 since I bought it new and I did it because, in light of the fact that 87, 91 or 93 makes no difference with my style of driving, it was cheaper. Why spend money on something you don't use or need (91/93 octane fuel)?
I guess you could say that about the entire prospect of buying an LS430 - you don't 'require' it so why not just buy a Corolla?!

 

This subject matter will continue through eternity. I used regular gas in my LS430 for years before I traded it and it ran as smooth as ever. Took it in for all it's maintenance and never once had one engine mishap. With that said, it doesn't change the fact that the sticker on the inside of the gas cap says use premium.

 

My Ls will always feel sluggish and slow compared to my soarer. It really just does not feel like a car that is meant to be drivin fast-ish at all. IMO. But as far as milage goes, i find that i get so much more milage running 94 grade fuel that the additional cost is well worth it.

 

In 6 years of LS430 ownership I burned 5,123 US gallons of gas driving 115,534 miles. When I purchased in 2009 premium was 20 cents more than regular and somewhere along the way it increased to 40 cents more. So I did a simple average at 30 cents per gallon and figure I saved $1,536.90 over the last 6 years. There were never any consequences, mechanical or otherwise to burning 87 RON gas. You can do what you want but I have that money in my pocket.
http://www.consumerenergycenter.org/...s_premium.html
http://www.businessinsider.com/what-...ium-gas-2012-9
Again, you can do what you want.

 

It must suck to have to worry about deciding if you HAVE to run 93 octane or if you can get away with 87.

 

I think if you're talking long highway trips, once the LS get's rolling, it doesn't take too much (under 2000 rpm) to keep it rolling at 70 mph. So, getting regular won't matter too much on long trips. I had to get regular once about 1/2 year ago for some reason, and I felt the drop in response on local driving. The car felt sluggish and the pickup was not as good. The local mpg showed it too, what usually was like 17 mpg, I only did about 15 mpg for that one tank. I have not done regular again since.


For me, I don't really care about the extra $.30/gal over regular for premium. I'd rather treat my baby to something good and have her last a while, than to cheap out now, and possible get big repair later. It might not happen, but that's why we get insurance. I look at it as cost to play.

 

This is a great thread.....props to Jabberwok for running the experiment and reporting the results.

I've always run 87 octane in my LS430......I also drive the LS in a mild manner, with the occasional WOT punch (maybe once every 1,000 miles) to about 80 mph. The technology on the LS allows the car (ECU) to adjust for a wide range of parameters, including the fuel's octane rating.

Simply said, if you want maximum performance out of your LS or have a lead foot, then you should run premium (91+ octane) fuel.......if you're okay with not getting the full 290 hp/320 tq (or whatever the manufacture rates the LS for) and don't push your car to the ragged edge, then regular (87) fuel is just fine. My guess is that Lexus tuned the car for premium fuel to make the hp/tq numbers look better against any LS competitors at the time.

As far as fuel economy, I would think it's more of a function of ethanol content rather than octane count but that's just my guess. The higher the ethanol conc, the lower the fuel economy.....but the premium fuel may have increased fuel economy over regular fuel as the engine won't have to retard timing.....so I guess it's really a toss up....and all pretty interesting stuff.

Randy G.

 

First World problems, right?