13 replies to this topic

[Millers Mini]

I have recently purchased a 1981 Mini HL 998cc and have been running it on unleaded for the past 60 miles, is this a problem?

[MiniKid..]

No, it must have been converted.

[Jammy]

No, it must have been converted.

Why must have it been converted?

It could become a problem, if it hasn't been converted to unleaded that is. Engines (or cylinder heads at least) built up a 'lead memory' over a certain amount of time whilst running on leaded people, so for the time being the unleaded petrol will be eating its way through this, and then it will go on to eat away at the valve seats and eventually cause problems with starting and running the engine.

Unless you have a receipt for the conversion being carried out, or your willing to remove the cylinder head and check for hardened valve seats then err on the safe side and use a lead replacement additive. I've used Castrol Valvemaster + (which is the same as Castrol Valvemaster, only with an octance booster as well) and its been great. Millers also do a good additive.

[Guess-Works.com]

Assume ALL minis prev 1989 run on Leaded fuel, unless you have documentary evidence to the contary

[adsta]

Just to get some clarification here because I'm interested in a 1989 Mini Sky at the moment - would that originally be leaded or unleaded?

[Holly]

i just add some green stuff when i top up (castrol i think)

although some one did tell me i could get my head changed for £50 they harden it or somethink?!?!?

[starrider]

when i had my clubby gt the bloke i bought it from said the engine still had the leaded head but don't worry because it has the leaded devise. when i asked what that was he said it had an inline lead producer. later i found out these were a bunch of poo and started using the additive. i never leave the petrol station without adding castrol on my current mini.

[Dan]

Mini SKY could be unleaded, best bet is to check the engine number on a car produced in this period as some cars were unleaded compatible from before the official changeover date because it was available as an option. If the car is in very original condition there could be a little sticker on the slam panel with a picture of a green petrol pump and a crossed out 'Pb' with 95 RON written on it. That means the car was built unleaded compatible. Then again, someone could have swapped the engine for an earlier one....

[taffy1967]

If the Mini Sky engine is original then it should be unleaded compatible, because the reason the Mini Sky and Mini Rose LE were made was to highlight their green running characteristics.

They were launched at the same time as the first wave of the Mini Flame Red and the Mini Racing Green LE's (plus the Mini 30 LE too) and they were all shouting the fact they ran green.

[minidaves]

running unleaded

Ok all older engines that have been run with run unleaded without to much of an issue for 1000's of miles and its not because of lead memory thats well gone as unleaded fuels and lrp have been around for donkeys yrs now, its because the seats are work hardend, thus being able to run a fuel with out the properties of lead, however if u reface or decoke an leaded head then try and run it on unleaded you will get about 5 miles down the road before the vlave seal is lost.

also remember minis were desgned to run on two star fuel that had lower lead content anyway.

so it will run on unleaded for a few 1000 miles with no issue and properly 10000 miles before giving grief runing with no additives on normal 95 ron fuel.

dave

[taffy1967]

My first Mini which was a 1975 MKIII Mini 1000 which ran happily on 2 star fuel. But by the mid 1980's, Minis were developed to run on 4 star and I seem to remember that most filling stations only sold 4 star towards the end of the 1980's (they'd fazed out both 2 star and 3 star fuel) by the time unleaded was introduced.

There used to be a website about the effects unleaded fuel had on a Mini engine that hadn't been fitted with hardened seats.

The conclusion was that it was best to use a good lead replacement additive, because eventually the lead memory would be eroded away. But if the Mini was going to be used heavily and at higher motorway speeds a good deal, then fitting a converted cylinder head was advisable.

[MTBBoy]

hya folks iz my 1983 austin mini sprite leaded or unleaded

[Big_Adam]

hya folks iz my 1983 austin mini sprite leaded or unleaded

*smashes head on desk*

Assume ALL minis prev 1989 run on Leaded fuel, unless you have documentary evidence to the contary

[Silicon Skum]

hya folks iz my 1983 austin mini sprite leaded or unleaded

*smashes head on desk*

Assume ALL minis prev 1989 run on Leaded fuel, unless you have documentary evidence to the contary

Ahh well, at least he obviously used the search function as requested, but maybe we should add that people should READ the contents of the search results aswell !

SS

Edited by Silicon Skum, 26 April 2007 - 10:29 AM.