Read the owner's manual; do what it says. Most vehicles only need the low octane fuel. High compression engines (such as in high revving sportsbikes) will require the more expensive higher octane fuel.
Exactly right, I have a C55 AMG and it literally has in all caps ‘SUPER 98 ONLY’ on the inside of the fuel door. But every other car I own gets 91 or e10 as that’s all they need. (I only put e10 in the cars that are driven very regularly as I know it goes off quite quickly compared to regular petrol).
Hooray, finally we hear from someone who knows what he is talking about when it come to "OCTANE", and thankyou mate. I learnt about it with the RR Merlin engine that throughout WWII continually increased the horse power by increasing the compression with supercharging. I think this is when 100 octane came about. As the boost continued to rise, so did the octane. By the end of the war the Merlin was running on 150 Octane (please feel free to correct me, I'm only going by memory here). Having said all that I did use 95 & 98 in a fuel injected vehicle in the late 1990s because 91 at the time was full of crap that blocked injectors and baskets (here in Aus atleast). These days I only drive a 1996 Commadore and it only drinks 91. I also use a 1944 truck with a 202 holden conversion. The old Red Motor hates 91, it was built to run on Super petrol back in the day which is about 95 to 98 octane. The only fuel it really likes is 100 octane Avgas, just saying.
I've had 💩 boxes that weren't worth rebuilding and had so much carbon build-up that they would only run right on higher octanes. My 2007 V-Star is like that now. When you add too much carbon to the piston and head, you're no longer running at factory specs.
This depends on how much of a 💩 box it is. When the carbon build-up on the top of your piston and on the surface of your head is really bad, this increases compression. In this case, you may want to run a higher octane fuel because your compression is no longer at factory specs and the car is probably not worth rebuilding the engine.
@@Stacy_Smith ah yes, a familiar story. My C55 is currently being rebuilt for that reason, hadn’t encountered and pre-ignition yet but plugs kept getting coated in oil.
Anything built in the last 30 years can run on whatever octane is available, the ecu will limit timing and richen the mixture to prevent pre ignition, and direct Injection improves the ability to handle lower octane fuel, i would recommend Top Tier fuel (in the US) or an occasional quality system cleaner.
Yes, I should probably do a breakdown soon on the other qualities of fuel beyond octane because there is definitely benefits to the various detergents and such they add to some fuels.
@@OhCar_Magazine A lot to cover. Automotive technology has advanced more in 15 years, than it did in the previous 50. I became a technician in 1991. I learned on pure analog / mechanical systems, but now deal with multiplexing multiple network protocol bus systems, hybrid and full EV vehicles, and it's just not 1991 anymore.
Yep, it really is crazy how far cars have come. I also am in no way an expert, just someone who is fascinated with cars/engineering and wants to share what I learn. I always appreciate any feedback on anything I get wrong or something I could include so thank you! Please feel free to correct me in future if I’m wrong about anything 😅.
Simply look at the fuel recommendations in the owners manual. Don't have an owners manual? Get one! Only use premium fuel if the manufacturer recommends it. It's typically required with high output engines, which can include a lot of non-sports car models. In New Mexico, it's common to see 86 octane fuel, which I hate. The owners manual says to use 87, which forces me to use mid-grade. I saw in a forum that 86 octane is sometimes used at higher elevations, where it is OK to use. Well, I live at 6,000 feet in AZ and we have nothing lower than 87 around here. I can't bring myself to use 86. Besides, what if I fill up with 86 in the mountains and then drive to a lower elevation? Nope, not worth it to me.
Yeah, I’ve heard about this high altitude towns selling very low octane fuels and I really don’t understand. Do they think you’re never going to leave town?!
The only time you should be using 98 (or anything rated higher than that) is when the manufacturer calls for it. From personal experience, I wouldn't recommend "cheaping out" on engines that call for 98 but *can* be run on 95 per the manufacturer - you'll get slightly worse gas-mileage and less power. And anything higher than 98 is usually a waste of money. Unless the engine is specifically tuned to run on V-Power/Ultimate/whatever - IIRC some higher-end Porsches came set up like that from the factory and some tuned cars might be set up for higher rated fuels than 98 octane. But these cases are rare indeed and folks who own a car like that will probably know.
Yeah, I’ve heard about this. The UK also recently changed regular petrol to E10 didn’t they? I will put E10 in my regular car as it’s quite new and gets used every day. I wouldn’t put it in my C55 because it’s not driven often and from my understanding ethanol goes off quite quickly. (The C55 only takes 98 anyway but even if I could put e10 in I wouldn’t for this reason)
There's one "brand" of duel I'll never put in my car again, and it's all about mileage - this brand gives about half the economy of the top one or two ... I also have a mate who worked 35 years in the fuel industry, and told me early on that the 91 octane fuel was significantly less stable than either 95 or 98 octane.
