my tech told me when he was working at main dealer when the 550 was first delivered, people from the factory came over to discuss the new car. With regard to fuel yes 95 was recommended and running 98 could lead to some parts(sorry I can't quite remember) getting to hot. This conversation was assuming straight fuel, no ethanol.
This YouTube ditty is quite pertinent to this thread. It shows the degradation of the rubber components in the fuel tank on a 550.
I'd be very wary of any advice given by "The Wizard". e.g. security modules in the footwell? Ferraris are not his speciality. I think his reputation took a hammering after YouTuber Hoovie's 355 went up in flames. I'm still trying to figure out why one side of the engine didn't go into closed loop mode because of fuel pressure. Isn't that based on coolant temperature and other engine sensors? Regarding his custom relay "switch". Why not just pull the relay or fuse?
Just realised his "relay switch" only has two contacts, so it's basically a jumper wire which forces the fuel pump on, irrespective of what position the ignition key is in or what the Motronics ECU is telling the relay to do.
The idea of my linking the video to this thread was as a visual real world demonstration of the degradation of rubber components in a 550 fuel tank.
There's a good article in issue 203 of Octane magazine (appropriately) re E10 in the UK. It seems E5 super unleaded will be available for at least 5 years after the introduction of E10, and will be reviewed subsequently after that.
We have been using E10 for decades here with few problems. The rubber in the fuel pump bases of the 550 would have come apart with no alcohol gasoline, too, in all likelihood. Problem is not limited to the US. Did not know the UK had a huge corn lobby like we do in the States. Why is this happening there since there is about a third less energy in alcohol compared to gasoline? There is a useful octane boost, however, so not all gloom and doom.
About m the possible problem with 98 octane said during the time when these cars were new, the problem is probably related to leaded 98 octane fuel. In Europe, the red super 98 was leaded for quite a while. Not sure when leaded fueks were discontinued in the various countries. Lead is very bad for sensors and catalyzers, so that is the reason why in the filler cap there is a «ubleaded fuel only» sticker.
It's the May issue of Octane, just out for subscribers even though it's not April yet... Full of useful info, with general message of don't panic but expect to pay more for E5, and expect some adjustments and increased deterioration with older cars. Leaded petrol was banned in 2000 in UK, so right in the middle of the lifecycles of our cars. According to the article*, ethanol is counted as renewable and offset 880,000 tonnes of CO2 a year in the UK in 17/18, with E10 to offset another 700k. In Germany apparently you could/can get both E5 and E10 95 but no one took up E10, partly as lower fuel economy as it has a lower calorific value. *sharing for info so please don't get into an argument about the eco merits! Keep safe John
Update by the Wizard on the 550 Fuel pump issue (the forums favourite non Ferrari mech). It appears the pump is also used in KIA's at considerably less cost.
In France, the 98 is E5 and the 95 is either E10 or E5, although the 95 E5 is rarely found (because 95 E10 is clearly cheaper than 98 E5, and accepted by all recent cars). The typical recommendation is to go for E5 (98 when 95 is not available) for older cars, even if they were designed to only require 95.