i filled up with bp ultimate a while back in my 93 WRX and after a couple of dyas the car was hesitating on full boost and the power was varying quite alot.

I filled up with optimax and within 10 miles it was pulling like a train again and had no issues for about 2 weeks.

2 days ago i put ultimate in again as i wanst near a shell, and today its doing it again.

Why doesnt it like ultimate, is there really much difference, especially with all these horror stories that optimax deteriates really quick..

Also, what benefit will i see from adding booster, will it help mpg too

 

My 99 wrx seems to run better on sul + booster than it does with optimax+ booster. Dont know about ultimate, no BP garage`s around my way.

 

I believe that with ultimate, BP took their old super unleaded and made a great leap. Unfortunately, they hadn't checked which they were facing first, so it was a giant leap backwards.

My car used to love BP SUL, probably even preferred it to optimax. It runs really rough on ultimate by comparison, you may as well use NUL at that point! Last time I used some as I was nearly out of fuel, and put £5 in to get me to the nearest "proper" fuel.

The only thing I'll say for it is I think the car runs better after it's had ultimate in and then re-fuelled with decent petrol. It may have cleaned something out a bit. Or it may just be that the car is so relieved to have real fuel back . . . .

 

is yours uk or jap

 

My first thoughts were good. Car (93 WRX, remapped)felt a little smoother than with Optimax. Great I thought. Then I refilled with Optimax, and the difference is like chalk and cheese. A real noticeable power difference with Optimax. So, as my local Shell station has changed to Texaco, its Ultimate plus NF.

 

what octane boosters are best then and where do i get them

 

NF is the best. I think Scoobymania sell it.

 

well heres to complicate matters further

ive just been out for a drive to the shop and on the way back i had a bit of a play, and it was absolutly flying.

Can only think its because its so cold out there that the poorer fuel was ok with that air temp????

any ideas

Ive basically decided on 2 options now

run on optimax, apparently 98.6 ron, but can deteriate

or my local esso SUL and millers octabe boost making 99ron, what do you think is best.

does optimax really do a good job of cleaning the engine?

 

Not as good as Optimax......though only down the road from me; SHell is about 8 miles though if using NF Race Formula with 6 ron more...who cares

 

I started out using BP SUL, then changed to Optimax, then went to Ultimate, then Ultimate + Millers, and now back to Optimax...

I initially felt Ultimate was better than Optimax, but it may well have just been wishful thinking, as there's only 1 Shell garage in my area, but about 5 BP... Since upping the boost a bit though, Ultimate on its own was giving the Knocklink something to do. So I started adding Millers. Problem solved, and so it stayed like that for a while. Then ran out of Millers, so tried Optimax on its own. Just as good (if not better) than Ultimate + Millers...

I think the Optimax deterioration problem is only relevant to garages in remote areas, or garages in areas with lots of other garages to choose from, where the general public are more interested in value for money than octane levels. Let's face it, the stuff doesn't stay in our tanks long enough to deteriorate...

 

RR

It might be best to do an ECU reset when you next fill up with fuel, early ECU's will back off advance if it detects poor fuel - but cannot increase advance when good fuel is back in. When you reset, it will go to max advance and then adjust down to the fuel in the tank.

 

The ECU does re-advance the ignition timing, just not as fast as it retarded it. A tad on the conservative side, you could say...

 

UPDATE.

went to scoobyparts today and got a couple of bottles of millers to try out.

put £10 of esso SUL in on the way there, and drove off boost.

picked up the millers then filled with optimax (£25) and a bottle of millers, drove home steady.

disconected the battery and as i had an hour to kill i washed and polished it.

Re connected battery and went for a drive, after about 20 mins i started giving it some, and its boosting like a dream.

I just cant decide if i should do Esso SUL and Millers or Optimax and Millers, as i hate these horror stories about optimax deteriorating to 95 ron.

Gonna buy a knocklink tho so i can see whats going on, but it looks like millers has solved all the probs

 

Fantastic news. I wouldn't lose any sleep over your fuel choice though. Both are good..

 

To be honest the amount of time it takes for my car to empty a tank of fuel,

i dont think optimax would deteriorate that quick

and with millers it runs really well

I tried ultimate once and the car hesitated on high revs /boost

 

My sentiments exactly...

 

Judge YHPM

 

Red Wrex, back at ya...

 

Won't ever touch BP Ultimate again. Twice had red light on knocklink with BP Ultimate - once even with a bottle of Millers!

Brother filled up his Corrado 340hp turbo with BP Ultimate and melted a piston minutes later on the M40... Coincidence perhaps but given the car has run like that for 2 years without problem... maybe not?

I would rather use Supermarket SUL than Ultimate.

 

I filled mine with ultimate to see what the fuss was about,and after a few miles when i stopped there was smell of unburnt petrol!
This never happened when i fill up with other petrols and after speaking to the petrol attendant i was told that ultimate is only 97 ron, but behaves like a 99 ron.
CONFUSED......i was,I'm not going to fill up with that stuff again!!

 

I saw a comment from SHELL saying their Optimax does not detoriate rapidly at all due to the fact that it gets its higher octane from super refined fuel - not additives. Therefore the tank life is several months.... Whereas octane booster and other additives have a short storage life.....