Modern Vespa

Do you think I'm going to have any problems? It took a little over a gallon to fill the tank this morning, so there was still some 91 octane in the there. Thanks!

No worries. If it were me I might avoid WOT for a while, that's all.

When I ride through Baja there is a gas station that only has 87. I use octane booster with it and seems to run better than 91. Without it I can tell a difference with the lower grade fuel. I bought the Royal Purple brand cause it came in a metal container.

I will. Thank you!

How does it react differently on 87? Rough idle? Loss of power? Just curious. Thanks!

Idle was OK. It's hilly where I get this gas and going uphill I can feel it has less power and is a little less smooth running. Haven't experienced any detonation but I didn't ride as hard like I usually do till I put better fuel in. I bet it would ping if I got hard on the throttle. The booster eliminates all that. I was skeptical till I tried it, now I use it every time.

Gotcha! I'll avoid open throttle until I burn all that gas up. Thank you!

The boosters work, since in the uk the difference between 95 octane and 97/99 was the amount of additive the tanker driver adds at delivery. Both fuels are the same from the refinery, the grading comes with the additives octane boosters / detergents added at final storage.

As a nipper I spent a week on work experience in a refinery. One of the jobs I did was to run the " knock"engine. This was a four stroke single cylinder engine with a variable cylinder / head, so you could change the compression ratio eg from say 9 to 13:1. As you wound down the head using a handwheel. When on the test fuel the machine would knock like two cavorting skeletons in an oil drum. You then backed off the wheel and recorded the compression at knock, added a measure of "iso-octane" then retest. This was 50 yrs ago so 13:1 engines were not unusual and five star was the premium fuel.

Thanks for the info, that's really interesting using the variable head to change the compression ratio! My engine is 10:1 and the manufacturer states 91 but able to use 87 for short periods. It sure loves the booster.

So how does that work with E5 and E10, where do they add the ethanol?

At the refinery.

nope

Running a 1/2 tank of 87 octane on a limited basis won't have any long lasting negative impacts. The engine won't run optimally and the lower grade fuel has fewer cleaning agents.

I would run some Seafoam or Techron fuel system cleaner to ensure you don't have any lingering issues.

Will do, thanks! I put a good 80 miles on her this past weekend. No issues except idle felt a little rougher. No biggie. Thanks!

The previous owner of my GTS said he ran Regular gas in it with no problems. After I bought it, the code light came on. After I started using Premium 93 octane, that light went off, and I haven't had any issues since.

What is better to use on a 2023 GTS300 90 octane with no ethanol or 92/93 octane with 10% ethanol?

A toss-up (and don't worry about ethanol from the engine's POV) - so use the cheapest.

There may be other reasons for avoiding ethanol or advocating it, but your engine's health isn't one of them, they're designed to use it.

I'm looking at my gas cans in the shed and wondering if I put 2t in the shifty or not.

What did I do? I thought I said just add the right amount of oil for the two stroke, no worries.