Petrol?

[blekkja]

All the companies seem to have "special formula" petrol now designed for making modern engines run good. Or so they say. Question is does any of that, in turn, make old engines run shit? I tried asking the gentleman at shell yesterday, but despite a fantastic beard I couldn't really get behind him. I've always preferred to use higher octane gas to make up for the lack of lead, and even more so now that I've got the TC set up.

So: is there a place which sells better juice than others? Where should I fill up?

[avenga]

Octane doesn't help with the lack of lead. Octane is all about compression ratio, it is the point at which a fuel will self ignite due to heat and pressure. I have upped the compression ratio on the panther a bit so I run that on 98 mostly, but she still runs fine on 95 although I don't like pushing it as hard on 95.

I don't know if a standard Avenger can run on 91, the 1300/1600's might because they are lower compression than the 1250/1500.

I use mobil 98, mostly because it is the closest place that sells 98.

[oldschool]

A standard Avenger runs fine on 91 with the timing set to 10 deg. With 98 it can be increased to 15 deg for more power.
David Vizard ran 20 deg in his racing Avengers with leaded fuel back in the day.
Z/Mobil/Caltex and BP 98 should all be the same, as it's refined here at Marsden Point.
Gull 98 is imported already refined with 10% ethanol included.
Use that in my 1600 TC Alpine without any problems.
I put Valvemaster additive in my carby dashpots to help reduce valve seat recession on unleaded fuel.
Still a good idea to check the valve clearances once a year as they close up over time causing burnt valves.

When overhauling the cylinder head, it's also a good idea to not fit exhaust valve oil seals, just install them on the inlet valves, which I think is how the original 1250/1500 Avengers were made.
While the motor will use a little more oil, the cooling and lubing effect of the oil with reduce wear on the exhaust valve, stem and seat, helping them last longer using unleaded fuel.

[blekkja]

In the past I have generally used 95 rather than 98 - though times where I've been a bit skint I've filled up with 91. Does anybody still do 95 or are they all 98 or equivalent now? (It's been 18 months since I was last on the road!)

[avenga]

Also, speaking of overhauling cylinder heads, I got hardened valve seats put in my 1500 so I don't have to worry about valve seat recession on unleaded fuel.

Most small petrol stations still do 95. around where I live on the North Shore, Mobil is the only one who does 98, my local Shell/Z,BP and Calex are all 95. Most of the big BP stations use 98 Ultra and almost all Mobil in Auckland are 98.

Outside of Auckland it gets harder to find 98, pretty much just the big ones on the main motorways. In the South Island it is next to impossible to find 98.