OutdoorKing Repair Forum Forums General Discussion Forum Off Topics Petrol Octane

Hi Tyler,

If you have a newer style car with EFI and a knock sensor than at least if you run a lower octane petrol the computer can compensate and retard the timing as to prevent the engine from pinging.

But on all older carby powered engines they just run at whatever it is set to and there is no automatic tuning for different octane levels.

I used to have an old tired Mitsubishi Colt with the factory 1.4 litre inline 4 cylinder engine. I tried to retard the timing a little bit but all this done was to make it have even less power than it already had..lol So I thought well i'll just set all the timing to the factory specs which was 5 degrees BTDC and I thought i'll just drive to the servo and try some of that premium 98 stuff in it. This thing was bad and was pinging quite a fair bit even at middle throttle opening. I am assuming there is a ton of carbon build up in the combustion chambers is was an original 1982 engine and never had been rebuilt or repaired. Anyway it pinged a bit all the way to the local BP servo then I filled it up with Ultimate 98, after I drove out of the servo and down the road a few minutes the pinging completely stopped. Not a peep out of it ever again, at all throttle openings I couldn't get it to ping again! lol

I think I once tried just using the premium 95 stuff and I noticed a slight return to the pinging every now and then, so I just stuck with the 98 octane after that.

But yes you are right most of the Australian made old school engines with cast iron heads like in the older Holdens and Fords from back in the day were the one's that needed the lead additive. Many imported engines like from Japan and many that have alloy heads already had hardened valve seats and these could be run on unleaded with no problems. Well so they say anyway...lol.

I have found and attached the old BP fuel guide and another BP fuel information guide that I downloaded years ago about the change over to using unleaded petrol in older cars from the old back up hard drive. I tried searching the net and I couldn't find these anywhere now.

Hi Tyler I checked the car list on this guide and it doesn't mention the Holden Camira as being able to run on just straight unleaded, is your Camira built after 1986? Because I think this guide if for pre-1986 vehicles only and i'm assuming anything made after that can just run on straight unleaded.

Cheers!