Is250 super unleaded or regular?

[Rebecca]

Hi guys I'm due to collect my new is250 this Friday as decided the diesel is not best suited to me as don't do enough milage to justify keeping it and from what I've read on the forum it very problematic . Yes I know I should have done my research beforehand . 

As regards to the is250 will the car benefit from more mpg. cleaner engine and better response using fuels such as shell nitro and bp ultimate or will regular unleaded be fine?

[NemesisUK]

Regular will be fine but for the small additional expense per tank I would (and have for my RC300h) use the likes of Shell V-Power, even if only to keep the engine/fuel system cleaner.

[ahmedali44]

Hi Rebecca good choice u won't be disappointed with is250. 

I use shell regular it's perfectly ok but occasionally use shell v power which does make a difference. make sure u post pictures when you pick it up

I had is220d se-l 2006 for 2 yrs only sold it due to doing not enough miles, at that time I made mistake like u didn't do my homework. 

[peachy]

Rebecca I've only had my is250 a little over 2 weeks and only filled up with shell nitro so far so I can't comment on better mpg or better response but it's nice to know the extra detergents added to the fuel will be keeping the v6 nice and clean.

A posh lexus deserves to be run on posh fuel 👍

[madasahatter]

I run on Bp 95 ron fuel, no need for and to pay the extra for a supposedly better fuel. There is a good utube video on fuel proven to be not needed for non

performance cars, no extra bhp as claimed by shell bp ultra etc. I never buy from asda morrisons and the likes. If i find the video i will post it.

It will open your eyes of all you people who think shell vpower is the bees knees. Its amazing the lies we are told.

 

[Verbout]

Normal fuel all day long, if you use the supposedly posh stuff, well........you know.

[NemesisUK]

Well you know.. it won't do any damage... (approx £8 extra per tank, no big deal)

[wendle]

as an X driving instructor for 21 years, i covered over 1 million miles, driving small 1ltr Austin metros, rover 100's and 1.2 ltr vauxhall corse's, each car covering around 160,ooo miles each before being replaced, now thees car did not belong to me, i paid a franchise every week, but the petrol money came out of my pocket, so of course i was only interested in buying the cheapest petrol around, which in my case was my local sainsbury's or asda, in all that time i never had any issue related to bad fuel, or engines clogging up.

so i think its down to each person to decide, but according to every report and TV program i have seen or read the outcome was the same, it only really made any difference, and only a small one at that if you are tracking your car.

 

 

 

[J Henderson]

Normal unleaded most of the time for me, but I will occasionally buy V-Power for it's supposed engine cleaning properties.

I could certainly feel the benefits of using V-Power in my old IS200 as the engine felt like it was burning more cleanly (smoother, sharper throttle response etc), but I don't think the same benefit can be felt with the IS250's V6.

[NemesisUK]

Some modern engines and certainly those of the German marques for many years have knock sensors and can adjust the engine ignition timings to make best use of the fuel presented. Definitely the case in my old CLS55, I could feel the difference when switching to V-Power.

Now, I know the engine in the 300h is nowhere near the performance tune of the AMG but it certainly can't hurt the engine to feed it with higher octane fuel and with increased cleaning additives. 

Does anyone know if the Lexus 4 pot engines have the ability to automatically adjust timing to account for octane rating?

[Linas.P]

Until now I have tried probably all possible brands of fuel and for a year have noted them in excel spreadsheet, with MPG etc. There are no difference what so ever in terms of performance or MPG (ASDA regular gives marginally best MPG), but from time to time I treat my car with some premium fuel just to help burn some carbon deposits etc. (premium fuels has additives to do just that). Overall, use of premium fuel only has benefits for long runs as engine accumulates carbon deposits slower, one thank would not change anything and even if you use only premium fuel engine still going to surfer from decreased efficient and power due to carbon and other deposits.

I would say better investment would be save money on premium fuel, but instead have engine "decarb" service once in a few years.

[Rebecca]

Thanks for the replys guys. My weekly fuel bill is only £20-£25 per week so filling up with super is probably only going to cost me a couple of extra pounds each week and worth it if it keeps the engine cleaner.

Only 3 days to go before I get my lovely new is250. it's a 2011 model with only 23000 on the clock.

[Brechin Slate]

Enjoy your new car, you won't be disappointed. Lexus customer service is another benefit of owning an IS250, all round it's a great package!

[Vintagesixtysix]

Nitro all the way for me.... 😇

Sent from my Iphone using Lexus OC

[cidersteve]

sainsburys regular seems ok for me ,also seemed ok in my 325i msport

[NemesisUK]

8 minutes ago, cidersteve said:

sainsburys regular seems ok for me ,also seemed ok in my 325i msport

I'm sure it's perfectly fine but wouldn't your MSport develop more bhp on V-Power? BMW and Mercs are held up as examples of engines that sefl-adjust to take advantage of the better fuel.

[cidersteve]

i'm sure it would Peter ,but just a 7 mile commute every day in traffic and the occasional blast down to devon and cornwall i don;t think i would notice a small increase in bhp ,just my personal opinion, but in this day and age they aren't many places in this country where you can go for a blast .

[Linas.P]

55 minutes ago, NemesisUK said:

I'm sure it's perfectly fine but wouldn't your MSport develop more bhp on V-Power? BMW and Mercs are held up as examples of engines that sefl-adjust to take advantage of the better fuel.

Same are true for Lexus IS250 which has "smart" ECU, which adapts to the fuel and drivers style.

There are no mystery about premium fuels... they have additives which improves RON numbers and can clean (or prevent accumulating) various dirt, sludge and carbon deposits in the engine. Same is true about £1 additives you can get in same Tesco or Asda, pour the bottle with your refill and you have yourself tank of premium fuel. In my calculation it works out cheaper to buy premium fuel, then regular + additives (varies between station and over time).

One way or another the improvement in power will be negligible ~ some argues 0.2-2%... and even that only in certain RPM range e.g. at 1500-3000RPM you can loose power due to higher RON, thus lower detonation, but gain power from 3000+RPM where higher RON actually enables your engine to run smoother due to less detonation and knocking. However, if you don't reach that certain range.. you will never get even that 0.2-2% increase and you can even loose power.

It is more to slowdown mentioned dirt from accumulating, whenever it could completely prevent it is a question... I guess it depend on the engine, the way you drive, other factors.. But anyway if you only goal is to prevent dirt accumulation.. then "decarb" service works out cheaper then premium fuel.

I must agree that probably the best ways is to use both premium fuel and decarb, but equally we are talking about several years and maybe 100k miles before you can actually feel any difference... by which time you probably going to upgrade car anyway. So really it is not beneficial to anyone (except future buyer) unless you planning to run same car for million miles.

[NemesisUK]

" the 2004 BMW 330 also does this, according to the driver’s handbook it makes 231 BHP on 98 octane and 221 BHP on 95. "

https://www.petrolprices.com/about-fuel.html

That's a significant increase?

[Linas.P]

It is indeed significant... I mean 4.5%. It is hardly enough for anyone to feel it, unless they "floor the car".

Again the article does not provide any evidence except "one user has commented", but if we look at what he commented about is that is mostly true an common sense:

1. Some engines can detect knock and reduce power - IS250 engine does exactly that.

2. Some engines requires higher RON fuel - that is because standard compression is higher on them, hence increased risk of knock 

The "231 and 221 hp" story is more likely to be range of HP to which ECU can adjust the timing to reduce the knock and therefore is roughly related to RON number ,but other factors should be considered e.g. time of the year, cold hot weather (air temperature), quality of the fuel which can increase or decrease RON number.

Now here we are talking about engines designed to run on higher RON fuel and ability to retard timing in case inferior fuel is detected, if the engine was not designed to run with 98 or 99 RON, then it would unlikely gain power.

Finally, we need to put car on dyno and run on both fuels to see... first of all find out where it delivers that 231hp on 98 or 221hp on 95. Maybe it delivers 221hp@4500RPM on both fuels, but whereas 95RON goes flat from there, 98 still rises to 231hp@5500RPM... In which case there could be an increase, but you won't feel or benefit from it unless you drive between 4500-5500RPM.

[is200 Newbie]

Wont the ecu in the car take time to adapt to the higher ron fuel? and so you wont feel the difference immediately, possibly over one / two tanks?

Also - with not a lot of cars seemingly using this higher ron fuel (v-power etc) then petrol will quickly "go off" so if deciding to use it then chose a garage that has regular deliveries as it can be sat in the forecourt tanks for quite a while before being re-filled and when you come to fill up it could be a rough batch.

[NemesisUK]

Agreed, needs at least a tank before effects are felt.

[Linas.P]

Good point... premium fuel tends to be less popular.. so indeed if you decide to fill up with premium go where it busy enough for it to shift before going off... or Use regular + bottle of additive. 

In terms of IS250, that is true.. you might need few tanks before ECU learns improved conditions and releases more power. However, there is specific sensor for knock detection - it would instantaneously drop the power if knock is detected.

[djkenn]

I find that in engine feels slightly sharper on premium fuel and there is a bit more power, it seems more willing to kick down. So following the advice I read here, I fill with premium every fourth tank (and then drive away smiling)

[peachy]

Some cars respond better than others when using premium fuels. for instance my previous is220d definitely felt more responsive with bp ultimate and gave slightly better milage over a tank.

My old vauxhall astra 2.2 Sri came to life when using bp ultimate unleaded .

I've had a bmw 328i and a 320d and premium fuels didn't seem to make any difference what so ever.

I'm still in the honeymoon period with my is250 and the moment and have used nothing but she'll nitro so far but sooner or later will switch to regular fuel and will post any difference I notice in response and mpg.