loden338

I just bought a 2000 E 430 AWD. Owners manual says use only 93 octane gas. Ouch, expensive!

I tried a tank of 87 octane (10% ethanol) in it, ran just fine. What is the truth here? My driving is mostly around town, some freeway at 70mph max.
Any comments, suggestions, experience is appreciated!

raymond g-

you have a high compression ratio engine, requiring higher octane fuel to minimize
detonation and pinging. don't be too penny-wise-pound-foolish as it may result in
long term issues down the road. short term, it isn't going to blow your engine up.

the car computers will make minor adjustments when it can in terms of adjusting
the timing. additionally, your fuel economy may suffer due to diminished performance
so you may actually end up paying for being frugal. fuels differ slightly so it's not
as if one answer is sufficient. there are a host of variables.

fabbrisd1

Three things....

1. Octane - please understand better-octane/superior-gas will give you the best MPG - and with lower-MPG on medium grade - you will lose about 1/2 that lower price per gallon to lower MPG

2. Fuel system cleanup - buy a $9 bottle of Stabil Marine Fuel Stabilizer (blue bottle) and dose 1/2 bottle at/just-before your next fill up to clean up your system

3. Fuel Filter - deserves attention - buy ONLY Mann or Bosch fuel filter - Mann right now is about $35. Replacement is relatively easy DIY - the original hose clamps down there are a "trickster" style - but can be easily replaced with generic hose clamps.

loden338

So then to be safe, premium fuel is the correct answer. And the cost/gallon difference adds only a 1-3 cent cent per mile driven increase. Given the few miles I drive, it is negligible.
Thanks Raymond & Fabrisi! Klaus will drink only the good stuff from here on in!