Hi,
does anyone know what needs to be done so older cars can be converted to using unleaded petrol? Thank you

Any original/standard superbug should run well on 91 ULP. Some volks prefer 95 ULP (not really necessary for original 7.5:1 compression engine -- but may be good "insurance" if your ign.-timing is way out!). If you hear PINGING on 91 ulp, change to 95 ulp.
You shouldn't need any additives, though again some feel happier using them.

Nothing for our old dubs, they run fine on unleaded but keep away from E10

Thank you both, this board is amazingly informative!

Beetles were Unleaded from 1968. Nothing to do if after this date.

All fuel is unleaded.

I wouldn't put 91 in my lawnmower.
Low octane fuel used to burn valves when it had lead in it.

Just do your VW a favour and put 95/98 in it. It can't hurt it.

Correct me if I'm wrong but I thought any engine that doesn't have stainless steel valves and seats should have an upper cylinder lubricant like Morrie's added to the fuel.

Original cast iron heads on other models of cars ran on unleaded with no valve seats at all, with hardened valves for many years. On unleaded they need the Upper cylinder head lubricant. Most cast iron heads now have hardened valve seats. If you converted a cast iron head car to LPG you had to get hardened seats.

Alloy heads usually have hardened valve seats anyway, so Lubricant is not required.

My wife was recommended by someone to put a tank of 98RON in the Beetle, and the car didn't run well at all, as the timing and compression is stock, so it is set up for 91RON. So compression ratio, timing and plugs need to be part of your fuel selection. It does all go together in a older carbie, distributor car.

Well actually no.
We VW owners (economical devils) in the 60's-70's usually ran Standard (or Regular) which was 89 octane min. (and often contained more lead than the the 98 super, but that's another story).
Or we used BP Super-Mix, with 25% Super (or whatever the minimum increment was) added to the Regular.

Use the lowest octane that will work well. Modern high octane fuel uses much higher amounts of "aromatics".

The sticker inside the fuel flap on my 73 Squareback says 91RON, and I run Flashlube with 91 at the recommended mix ratio. I have been driving it as my daily driver (up to 2 weeks ago, when I was taken out from behind) for the last 5 years, and the previous owner for the preceding 6 years.

The car doesn't ping, gets great economy, and for a dead stock engine develops good performance, uses bugger all oil between changes.

Nymeyer's VW specialists at Belmont North (near Newcastle) recommend nothing else for a dead stock engine of that era!

Why do you need flashlube then?

Because engines run a bit hotter on unleaded than they do on leaded, and for the price it's a cheap additive!

No, flashlube won't make it run cooler, but will provide a measure of valve/upper cylinder lubrication that was previously provided by leaded fuel. According to advise given to me by the reputable long time VW specialist mechanics previously mentioned, VW engines run hotter on unleaded fuel be it 91, 95 or 98, and due to a stock engine being of low compression, there is no benefit to be gained by using higher octane fuels!

These guys know their stuff, being second generation VW specialists, so I for one trust their opinions, if others don't choose to, so be it, I can only judge on how my car performs, and as stated previously, it performs very well!

Dont buy high octane fuel from servos that have low turnover, it can go stale

Or if the temp goes over lo-mid 40s with the sun on the bowser, it won't even pump.

If you're tuned to run 98 then you're inside drinking crap roadhouse coffee for hours until the pump works again.