I have lexus GS430 2006 Model, Does it harm to engine If I fill up unlead gas instead of Premium Gas

yhchung

I have lexus GS430 2006 Model, Does it harm to engine If I fill up unlead gas instead of Premium Gas

thecardoc3

Because of the computer controls ability to detect and correct for engine pinging (knocking) you can temporarily run 87 if 91 isn't available. That of course "assumes" that the engine controls are working correctly. The octane rating required for a gasoline engine is a function of the engines design, specifically the compression ratio. The higher the compression, the higher the octane requirement to prevent pinging and possible engine damage. Page 518 of your manual describes the fuel requirements for your GS. Here it is if you don't have the manual.


So if you are looking for advice, use 91 all of the time. If you use 87, the computer will have to react and retard the ignition timing taking away both power and fuel economy to try and protect your engine from damage. That's why it says you can do it temporarily if 91 isn't available, emphasis on the word temporarily.

kyfdx

yhchung said:

I have lexus GS430 2006 Model, Does it harm to engine If I fill up unlead gas instead of Premium Gas

Maybe, we can get @thecardoc3 to weigh in on this.

Mr_Shiftright

Like Doc says, it's fine in a pinch, but I wouldn't make a habit of it. You will notice a difference in how the car runs. You need a finely-tuned ear to tell if a car's engine is pinging (pre-ignition), so if your car's computer (or the knock sensor) isn't working correctly, you might not realize that pinging is occurring. Heavy pinging over a period of time can absolutely damage an engine. Mostly it sounds like a chain dragging under your car when the car is under some load. (hill climbing, etc).