Unleaded Petrol Vs Vtech Petrol

[boltz]

Can anyone help me with the answer to this question. What are the problems with using normal unleaded fuel versus super unleaded 91.in an IS259. Thankyou. Boltz.

[Lexus Nerd]

Let's all make sure we understand your question right ... Do you mean to ask,

What are the problems with using normal unleaded fuel versus super unleaded (such as Shell V-Power, 98 RON) in an IS250?

From my recollection of the IS250 Owners Manual, normal unleaded (91 RON) is acceptable, but Lexus immediately follows this statement with what to do if you notice engine knocking. It doesn't give the reader a feeling of confidence in regular unleaded!

I also just learned that lower octane fuels in Australia (even 95 RON!) are likely to have a high sulphur content that will result in greater rotten-egg fumes in an IS250 than what you would normally expect out of the average car.

[LexWizz]

Also some one in the industry told me that 91RON is a dirtier fuel and will eventually clog the system.

So you will have to run some kind of fuel additive on a regular basis if you want to maintain the efficiency of the system. Depending on how many kilometers you do in a year, it might be more economical to buy the better quality fuel.

[evolutune]

Direct injection and very high compression has a lot to do with why high octane will help. A pure fuel will leave less carbon build up. The direct injection on an 4GR has a few teething problems due to running dry valves and no port injectors. It tends to have issues with carbon build up thanks to that. I do wonder if a valve saver injector like you use on lpg setups would aid the issue.