What petrol is the best for standard ECU on EF/EL I6?

[mark_TD]

Stick with 91 octane if it is running good. 95-98 wont do much better unless the compression is high. Also some cars dont like it. It come out of the factory to use 91 so you are better off sticking with it unless you modify it and advance the timing. I use premium only because it is a 5litre and it hate 95 octane or lower. It seems to ping alot. If your car pings however you are better to use premium. I only use BP ultimate or shell Extreme (now V Power 100)

[SupahStah]

You will generaly only notice a difference with premium fuel once a car is advanced (except in EFs which, as posted earlier compensate themselfs) Once the car is advanced. I have found if you run 100 Octane from Shell, you can advance an extra 2 degrees compared to other premiums (About 10 degrees in total) safely without pinging. The Mobile Premium (98 oct) I stick to will run safely on 8 degrees advance.

Shell 100 Octane is alot cleaner, and it does have a difference, mainly in response and fuel economy. And is my pick for performance (if tuned). Mobile 98 however I think is better value for money, as in most cases you dont see a difference except how clean they burn.

If I was to run normal unleaded (91) I cant advance it past maybe 2 degrees above stock without running rough / pining somtimes. You get what you pay for, depends how much you love your car lol

SupahStah

[ef_classic]

I just got back from Mildura.

I drove from Castlemaine to Mildura in my ef sedan.

I had managed 650ks so far out of the 68 litres of BP ultimate i had put in it, i still had a bit left, but i had to fill up again to get home.

Does that sound right?

[NC_GHIA]

I use unleaded and thats it standard shell unleaded... And if I want to give it a flush I use Prostrength octain booster...

[Bill_R]

Originally Posted by mark_TD

Stick with 91 octane if it is running good. 95-98 wont do much better unless the compression is high. Also some cars dont like it. It come out of the factory to use 91 so you are better off sticking with it unless you modify it and advance the timing. I use premium only because it is a 5litre and it hate 95 octane or lower. It seems to ping alot. If your car pings however you are better to use premium. I only use BP ultimate or shell Extreme (now V Power 100)

That's how it goes. Octane rating = tendancy to detonate. There's a difference, however, between the calorific values of the standard fuels v's the premium fuels. Premium fuels often also contain more additives which might be beneficial. Fuels aren't rated to show the calorific value. Premium fuels can (but dont' always) give more power and can burn more efficiently but not based solely on their octane rating. Higher octane fuels also burn more slowly which can have a -ve impact.

with a std compression go for std fuel unless you really notice a difference with the premium yourself. Throw a bit of cleaner in it now and then if you want to compensate for the less additives. I wouldn't base the decision solely on octane rating unless you have a high compression engine or want to play with the timing a bit.

[chich]

I tend to alternate between the two. A few years ago i ran my EF only on Optimax and had starting issues where the car would cough and splutter before kicking over. These days i tend to use 1 tank of premium to 2 tanks of unleaded however in summer i swap it around and use 2 premium to 1 unleaded. Another thing i do is reset the ECU at every oil change (5000km), i find that has the biggest effect on performance and economy.

[Heffnic]

in my ef i use the 98 octane it makes my car run a s**t load better but that was after about 2 full tanks to rinse out the normal unleaded. feels alot smoother as for a bit more boost a bit but nothing over the top.

[finnyman]

i ran 98 always until 100 came out, big difference between the two....i use nothing but 100 now, i wouldnt go back..... performance is sooo much better when you think its just the petrol....u would think u made a mod on the engine

[slayer351]

I was using regular unleaded in my eb then changed to PULP and got a lot better fuel economy. I am getting anywhere between 50 and 100 k's to a tank more.

[Interceptor'85]

I find the best fuel efficiency is the higher octane fuel. I noticed it lasted longer. Tried the norm a few months back. It went through the car like a mulcher.