Mk3 Cavalier Owners Club | Vauxhall Cavalier Dot Com

The RON plug on my V6 has A on one side and B on the other It's the brown type.

Anyone know what they mean? It's currently on A. I assume it's similar to 93/95 that is on my other Cavaliers.

A and B are instead of the actual Octane number printed on the side.
Brown 95/98 RON plug (i.e. A = 95, B = 98 setting).
The colour is primarily to identify the Ohms resistance - brown is 220 ohms.

Thanks Dave, so shall I switch it to B? Would it make any difference? As today's fuels are better.

Cavalier342 wrote:Thanks Dave, so shall I switch it to B? Would it make any difference? As today's fuels are better.

Standard unleaded in 95 Andrei, you may well find it 'pinks' if you do.

Ok cheers mate. I'll leave it be.

So you'd be better off running B on super unleaded and A on regular 95 octane?

Would it make any difference if I did put premium in and swapped the plug? Apart from my wallet of course...

Thread resurrection!

Just found this plug in my V6 and I was quite surprised to see it there.

Isn't the V6 supposed to automatically detect whether or not it can advance the timing with it's knock sensors?
therefore negating the need for a RON plug?

No, they are still fitted for some obvious reason. May as well add something while I'm here, I didn't notice any improvement in MPG or performance when I swapped the plug over and ran it on premium, so in all honesty just leave it be, they run fine on normal unleaded, as the fuels are better nowadays anyway.

James McGrath wrote:...Isn't the V6 supposed to automatically detect whether or not it can advance the timing with it's knock sensors?

therefore negating the need for a RON plug?

I think you're right
if it's on your latest ride, it's not a RON plug any more, it's a regional code settings plug, used mainly for noise emissions I vaguely recall

colin1 wrote: used mainly for noise emissions I vaguely recall

If that's the case then it didn't seem to make my old V6 any quieter, the noise that beast put out was unbelievable!

colin1 wrote:it's not a RON plug any more, it's a regional code settings plug, used mainly for noise emissions I vaguely recall

Interesting. Any idea which side is which?

Cavalier342 wrote:...... I didn't notice any improvement in MPG or performance when I swapped the plug over and ran it on premium, so in all honesty just leave it be, they run fine on normal unleaded, as the fuels are better nowadays anyway.

I always use v-power,( but not a slave to it). I've used 98 over about 6 years, previous sri & current cdx, 3 years on each. The cdx has only had super-unleaded.
I changed to 98 on the sri when I became aware of the horrors of 95 RON ( surely a classic car killer), with it's corrosive 5% ethanol added, ( 10% in some south England areas apparently).
https://www.whatcar.com/news/new-e10-fu ... motorists/
There was no noticeable difference until I had to fill-up with regular petrol on holiday - less power, lumpy drive, a bit of pinking. Back to normal after 98.
From what I understand higher octane petrol reduces pinking, has no ethanol added to (falsely, imo ) boost the octane rating, while at the same time reducing power. It seems ethanol will accelerate rot in just about everything on an old car over a short time.
The comments here are worth a look : http://www.motoring.com.au/98-ron-fuels ... oin-25725/
Now, I would never use anything less than pure(ish) petrol.
Why spend the money we do to keep loved cars running then scrimp on diluted petrol ? To me it's like fitting re-moulds or buying brakes from china-just not worth considering.