hey, been reading up on how i can use unleaded in my a12... couple of questions?

1. Do i have to wait till i finish the tank before filling with unleaded? or just put it straight in with the leaded...

and 2. is there much of a difference using a high-octane fuel like.. ie: BP Ultra or shell Optimax

it would be better to use premium or hi octane 98ron fuel with a dash of valve master or similar for lead replacement, then tune you car for it and you will find it runs more economically and a little more powerful than with normal ulp or lead replacemnt fuel.
lrp only has a 94 ron apparently.... and a theory goes that as engines age, and the tollerances become grater, they actually crave higher octance for producing power.
just dont use caltex gold, it makes my car stutter. Tkaes 3 tanks of mobil 8000 to fix it right

I thought using non leaded petrol for a long period of time damages the engine if its got brass valve seats, as new cars have steel seats and much stronger.
I dont know if 120Y have brass valve seats though...
But you should be able to just mix the petrol, if you're too worried about it use as much leaded petrol and when you know you are near empty then fill it up with unleaded.
Premium is better than normal unleaded as most of them have 98 octane this is based only from the people I know running it and compared to normal unleaded

This is a good question. When I was looking at buying the ute I downloaded a pamphlete from BP that indicates that the A12 is OK on normal ULP.

what it does not say is what if anything you need to do to do that.

I will watch this thread with interest.

wait a minute....

brass inserts are what you pay for when you convert your head from leaded to ULP - if you have them already (ala L series engines) then running ULP shouldn't be an issue.

yes thats what I said
engines with brass valve seats should use lead replacement fuel
but if you have replaced this you dont have to worry about it then...


Lead replacement petrol (LRP) was developed by the oil companies to replace leaded petrol, and enable pre-1986 vehicles to continue to operate satisfactorily. LRP is essentially unleaded petrol with a RON of 95 to 96, which has had anti-valve seat recession additives included to protect leaded engines from valve and valve seat damage. LRP is suitable for vehicles made before 1986, which are not fitted with catalytic converters. LRP is covered by the national fuel quality standards.


Owners of pre-1986 vehicles can also use a high-octane PULP, although an aftermarket anti-valve seat recession additive may need to be used to protect the engine. Otherwise, modifications to the engine could be considered.

Well i have run Premium unleaded (BP ultimate 98) in my 120Y for 4 years and it hasn't missed a beat, so i say use it i never put in valve save or anythiung like that and it all seems fine.

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ah! okay, it wasn't exactly clear with what i was reading.

sorry...