Fuel - Regular? 99 Lx470

[Bick Montana]

Have a 99 LX470 -- can you run regular and if so what are the potential issues if any -- Thanks for your thoughts

[denslexusgx470]

Bick Montana,

First of all, welcome to the club.

I'm not really familiar with the 99 LX, but I will say that it probably requires premium unleaded.

Now folks, correct me if I'm wrong but please be mature and keep this topic problem free w/o any arguments against the different grades of gas as I don't want this to turn into one of those gas/oil debates that get really nasty.

Thank you

[Bick Montana]

................ BUT I DO WANT SOME FEEDBACK - IT SAYS TO USE PREMIUM -- BUT CAN IT RUN REGULAR AND ARE THERE ANY PROBLEMS IN DOING SO?

[Jim_Chow]

What does your owner's manual say? IIRC, the earlier LX/LC's (98-02) were spec'd for premium while the '03+ says to use 87 or better. You only get the advertised performance if you use premium, as the engine ECU will alter the mixture/timing to accommodate the lower octane. I get about 2mpg worse w/ 87 vs 91, so it's cheaper to run 91, plus better on the engine. I get 16/19 running chevron 91, stock sized bridgestone dueller HT tires inflated to 32psi front & rear.

[LXPearl]

The 98 takes 91 octane. It will run on 87, but with less power and less MPG. My 01 is rated for 87 with a "recommendation" to use 91 for added power. Mine does not have as much difference on MPG as Jim mentioned - I see less than 1 mpg difference, so it is a wash on using regular or premium. However, I run premium because it has better torque around town and seems to run smoother, and I like the slightly better MPG and throttle response. I get about 14.5 overall, and essentially equal the sticker on specifics (13/16) with premium.

I had an 01 LC that I routinely ran regular in (except when loaded) and it was about 0.5 mpg lower than the LX.

[Shareque]

I've cleared 101K on my 2002 LX470 and used regular unleaded for just about every one of those miles. I did try premium for a couple of tanks, and felt no difference in power or efficiency. There have been no breakdowns and the vehicle has been in the shop only for regular scheduled maintenance. I continue to run a '93 LS400 (155Kmi) the same way.

[Lucky13]

These vehicles say that they need premuim because the engines are designed with the ignition time of the higher grade fuel in mind. So when you say wil regular give you "problems" probably nothing you would notice but it is not what the engine was designed for.

[congo34zulu]

I've cleared 101K on my 2002 LX470 and used regular unleaded for just about every one of those miles. I did try premium for a couple of tanks, and felt no difference in power or efficiency. There have been no breakdowns and the vehicle has been in the shop only for regular scheduled maintenance. I continue to run a '93 LS400 (155Kmi) the same way.

I agree with this statement. I have run Regular vs Premium and have noticed NO difference !

[Lucky13]

I've cleared 101K on my 2002 LX470 and used regular unleaded for just about every one of those miles. I did try premium for a couple of tanks, and felt no difference in power or efficiency. There have been no breakdowns and the vehicle has been in the shop only for regular scheduled maintenance. I continue to run a '93 LS400 (155Kmi) the same way.

I agree with this statement. I have run Regular vs Premium and have noticed NO difference !

Thar because you are a driver and not an engine.

[congo34zulu]

I've cleared 101K on my 2002 LX470 and used regular unleaded for just about every one of those miles. I did try premium for a couple of tanks, and felt no difference in power or efficiency. There have been no breakdowns and the vehicle has been in the shop only for regular scheduled maintenance. I continue to run a '93 LS400 (155Kmi) the same way.

I agree with this statement. I have run Regular vs Premium and have noticed NO difference !

Thar because you are a driver and not an engine.

You're right, I am the driver and my engine told me there was no difference !

[LXPearl]

The engine is designed for 91 octane and runs best with premium. However, the computer is also designed to adjust to 87 octane and runs without knocking on regular. The difference is usually slight, but there are differences. The most noticeable is driving along a hilly terrain with cruise control on. With regular gas the transmission will downshift more often than with premium, and the heavier the load, the more it occurs. Admittedly, this is not major for many people, especially if living in flat terrain and lightly loaded.

The Toyota technical course on the TIS site covers the ignition control for all Toyota engines with the adjustable ignition feature. Toyota found that all perform better with premium fuel, even those rated for regular (mostly Toyotas). For Lexus, they went back to recommending premium because enough customers noticed the difference in drivability when using regular and complained about it.

If you want to run on regular, it will most likely do so very well. It might get a little less mpg depending on conditions. It will get less horsepower and torque, but most will never notice a difference of about 5 HP. If you run regular and have a load and it starts knocking, you can add premium to get it to stop. The computer is designed to adjust quickly when changing from premium to regular, but other than adjusting to the knock, the computer has a staged timing adjustment when moving from regular to premium, so it will take multiple tank fulls to fully realize the true difference in performance when using premium.

[Texasoil]

By Federal LAW, all gasoline engine vehicles sold in the US MUST be capable of operating without damage on 87 AKI gasoline. Higher compression engines like the LX and other cars that 'require premium' are equipped with sensors that detect fuel knocking (detonation) and generally !Removed! the ignition timing enough to stop the knocking (and likely engine damage).

However, the engine will not deliver its rated power or fuel economy if it is more than lightly loaded. Under light loads, fuel octane really is not a power limiting factor and the timing is adjusted normally. When more power is asked for,, the fuel octane rating comes into play and the ignition timing has to be retarded from that optimal for higher rated fuels. This reduces the power output somewhat, will cause higher heat loads on the radiator, and lower fuel mileage.

If you don't use or call for the power potential of the high test stuff, 87 might work just fine. I would NOT recommend pulling a load up a long grade on a hot day though.