91 Or 96 Premium?

[edwardch]

what type of petrol do you guys use? 91 or 96? my IS200 uses 96, but I was just wondering if I could put in 91 as well? will it do any damage to the engine or the car at all? thanks

[NickF]

As far as I know, we only get 95, 97 and 98 RON fuel in the UK. I don't think that anything as low as 91 is available. It might be better asking the question on the US forums here. I think that most IS drivers in the UK seem to use 95 RON (standard unleaded), but some use 97 (Super Unleaded) and 98 (Shell Optimax).

[ColinBarber]

What is the fuel graded as in NZ? I guess not RON. If it's PON, the same as the US, then 91 is fine - that is the same as 95RON which we use in the UK.

[edwardch]

What is the fuel graded as in NZ? I guess not RON. If it's PON, the same as the US, then 91 is fine - that is the same as 95RON which we use in the UK.

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Unleaded 91, and 96 premium, only these 2 in NZ.

[NetOne]

Sorry to repeat the question, does it cause any damage to the car at all by just using 91 octane unlead fuel all alone? 91RON is a lot cheaper than the 98RON. So which type of the petrol (91, 95 or 98) is the most efficient in term of cost concern, ie with $100 of petrol which one will do the most distance ? Thanks for any comment.

[Andy_F]

Lower ron shouldn't do any damage to your engine, but it will run less efficiently and you will get a drop in performance. In a high-compression high-performance engine, cylinder conditions might let the lower ron stuff ignite too early. In extreme cases this can cause severe damage - because instead of a smooth rise in pressure as the piston is traveling down anyway, you get a pressure wave slamming into the piston as it's moving up. So basically, 91 should be fine for normal driving if you really want to use it.

For what its worth, I would stick with the 95. My car much prefers starting on 97 ron than 95, so I dare not think what it would be like on 91 ron.

Obviously, you will get more miles for your money with 91 ron since it is cheaper, so you can get more petrol for your money.

Isn't it reccommended that we run it on 95 ron anyway?

[jasestu]

What is the fuel graded as in NZ? I guess not RON. If it's PON, the same as the US, then 91 is fine - that is the same as 95RON which we use in the UK.

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Unleaded 91, and 96 premium, only these 2 in NZ.

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No no, we do have 98 RON in New Zealand - go to the New Zealand Altezza Forums and discuss there. (Specifically, this thread)

98 is marketed by BP as "BP Ultimate" (link), Mobil has it as "Synergy 8000" (link).

Shell's "Ultra Hi" is 95 RON

Read more in this discussion paper.

And on the fuel company websites: www.shell.co.nz, www.mobil.co.nz, www.bp.co.nz

Does the RS200 Altezza's 11.5:1 compression ratio qualify as 'high'? For what it's worth I run 98.

Edit: Yikes, just realised how old edwardch's post was, guess I'm not going to be a lot of help now...

Edited December 8, 2005 by jasestu

[ColinBarber]

I would say 10.5:1 and over are high.