"Petrol station has changed my 100 octane petrol to 98 and now I dont know where to get my petrol from"

So apart from looking at numbers, why  not explain from  a technical/engineering  point of view what you  understand by the figures, and why you "might" be concerned"  that you can only access RON 98.

Your engine specs would be of interest!

nɥºɾ