When I got my IS, I was always using regular unleaded 95RON to fill her up! Recently...and mainly because I keep reading Mat W's signature <--sheep , I have been filling up with Shell Optimax, which as I understand is 98RON...it's great, I actually think it makes the exhaust note louder and the car feel more sprightly.....

However ....reading a couple of recent posts I keep getting a sinking feeling that I'm doing my baby some harm!?!?!

Please help calm my fears guys and girls...I know you will!!

Cheers - Neil

Your doing your baby no harm at all...

I only use Optimax which is rated as a min of 98 RON and have only put anything else in a couple of tmies when caught out....

The difference is noticeable and I am sure there are more than a few threads oin this topic by searching

Just a suggestion....

As with any new engine or fuel modification, (except full ECU remap/upgrade), I'd suggest resetting the ECU.

Gives your ECU a chance to adjust to the richer fuel, and give you a bit more power.

See this thread for a current discussion on ECU resetting.

See [url="http://www.lexusownersclub.co.uk/forum/index.php?act=ST&f=64&t=7142&hl="]HERE[/url]

i was running my car on "optimax" and it started to run as if a plug lead was breaking down . i went to lexus chester and explained what was happening , the first thing he said "are you using shell optimax" which i said "yes" and his reply was "don`t" it won`t harm anything it just does not agree with the car were his words . so there you have it ! as they say the choice is yours ! i stopped and its been spot on !

is optimax just a fancy name for super unleaded?

and can't you use super unleaded in any unleaded car for better performance?

obviously this isnt the case but i'd like to know the reason if anyone knows

Unleaded is 95 RON
Super Unleaded is 97 RON

Optimax is 98 RON

They do RON RON RON they do RON RON..

Optimax has a higher Ron rating than super - but a lower calorific value. It also 'goes off' quicker - so don't use if it takes you ages to empty a tank (not likely with the Lex ) .... Try Esso Super - a lot of those in the know rate this much higher than Optimax, and they can better explain that I can the reasons why.

I tried optimax and the engine management light woke up on the dash. Haven't used it again and the light has gone back to sleep.
Coincidence maybe?

ok
low on fuel on mon filled up with standard texaco fuel

the car is now a dog


we shall see what hapens when i re fill with proper stuff

Thanks alot for the suggestions guys! Most appreciated, mixed....but I feel a little safer about it now!

Mr. G...thanks for the link...gonna try that today!

Hey costs a little more.....but makes the car feel much better!!

[quote name='UltraViolet' date='Jun 26 2003, 10:23 PM']Optimax has a higher Ron rating than super - but a lower calorific value. It also 'goes off' quicker - so don't use if it takes you ages to empty a tank (not likely with the Lex ) .... Try Esso Super - a lot of those in the know rate this much higher than Optimax, and they can better explain that I can the reasons why.[/quote]
Can you define 'ages'? I only drive 7500 miles a year, so I only fill up every 2-3 weeks!