Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Petrol 95/98 differece

Ruut, IMHO your CVH carburettor engine should be set up to run fine on 95 octane, unless it has been altered in some way. However, if you can detect knocking or pinking, then to be on the safe side you've got two choices, either run 98 octane fuel or consider using one of the octane boost additives that are on the market.

Thanks Philip. I think I switch to 98 for a while and listen carefully. I drive the Morgan since 1996 and it was the first time this year in the UK (TOTH) that I thought to hear some knocking on mid-revs, uphill, but I'm not 100% sure about that. It's always serviced by a very reliable Morgan agent and there are no alterations, except a sport exhaust, but that mod was already done already 20 years ago!
I never used the biofuel mixes that you can get in Germany (I live close to the border), because I'm afraid for the old fashioned tubing, etc.
So with our mileage it's just spending a few euros more.

My understanding is that 98 has a far lower Ethanol content. Ethanol has detrimental effect on plastics and rubber i.e. Petrol filler tube, plastic section of petrol cap etc. on my bike the Ethanol swells the plastic on the filler cap to the point where you can't get it off ! It has to be regularly sanded down to keep it free. Common on KTM bikes. The Morgan has a tight fitting plastic cap, I worry about it swelling and jamming.

So, that's one reason more for 98!

I have a 1997 T16 and have tried both 95 & 98 octane. It runs smoother on 95 octane.

Davis

My Morgan, an ''89 CVH, I have run on 95 ever since I brought it nine years ago. The previous owner had the carbs set for Leaded fuel, I have no idea why, so I had everything retuned when I first owned it. Earlier this year I tried 98 from Shell and found I was getting much better MPG. but as someone said a lot depends on driving styles, roads, and the state and age of the car.

Steve, I think our Mogs are quite similar. I always used 95, and do so for almost 20 years. I presume you now switched to 98, I intend to to do the same!

My handbook advises either 95 or 98 octane (model and engine details below). The engine pinks at 2000-2200rpm and I believe 98 octane minimises it somewhat. Nevertheless I do not linger in that rev range.

I never saw a difference on my T16 +4. I do on my diesel Merc. I dont on my V6 roadster series

The 1.6 Ford Sigma engine is designed to run on 95 octane in the mild state of tune in the 4/4 Sport. Mind you, supermarket 95 may not be ideal!