I have 93 Audi S100 with 113.000 miles on it - runs like new and feels like new. I'm having some concerns on the gas type I should be using. This car was manufactured in Germany - everything is written in German..even the whole manual and nothing in English. The only English that I can read is on the dash board it says "USE UNLEADED FUEL ONLY" . I heard the fuel type here in the US and Europe is quite different... So which one do you experts think I should use... REGULAR, PLUS, or SUPER. Also is it OK to SWITCH gas type.. My brother in law told me its always a good thing to get the most expensive (super) gas type once a month and is good for the engine.

Please elaborate

 

I suspect that on a 15 year old car it won't really matter. Go with the cheap stuff - and it can't hurt to use premium once in a while.

 

On a car as old as yours I don't think you would derive anyGIANT benefit, peformance-wise, from using the good stuff. You will definitely notice a difference in your wallet, to be sure. As old as it is, your car is still smart enough to *know* when it has a tank of premium vs. a tank of gasohol (ummm... do NOT use gasohol in your Audi). Running teh good stuff will get you slightly better performance and slightly better mileage; also somewhat cleaner fuelrails & injectors. You could also get the same benefit from running a can of octane-booster or some similiar OTC additive, periodically.

You could split the difference and run whatever passes for mid-grade, in your area, along with teh can of additive, I suppose.

Swing by eBay and pay $10-$12 for an english-language manual for your car. Money well spent.

Switching between grades of gas is acceptable, again, since your car is as old as it is you run less of a risk of gumming up the works, but, it is still smart enough to *know* when you are economizing, and adjust it's performance accordingly.

Your brother in law has half-a-clue, which is better than no clue at all. A can of octane-booster/fuel-injector-cleaner, once of twice a month will gve you the same benefit of running a tank of premium without leaving a empty, gaping hole in your @44 where your wallet used to be,

 

performance is made on thelowest octanegas that can border detonation.

alot of people think of it backwards... because most performance cars require higher octane to prevent detonation.

So try a mid grade.... if your not detonating... go lower... if for some reason 87 detonates on you just add octane boosters and use the higher grade next time.

i kno overseas there low grade octane is in the 90's

 

Try a couple tanks of all grades and use the one that nets the best fuel milage.

 

I was using the lowest octane on my 2000 A4 and when I switched to premium there was a noticeable difference. I'm not sure if it matters in a car as old as yours but it can't hurt to try.

 

Age can play a difference in optimum fuel efficiency either way. Carbon buildup can cause the engine to have a higher compression than new. However, mechanical wear can cause a lower compression than new due to leakage in the rings, valves, etc. In any case finding the grade of fuel that provides the best fuel economy will give you the optimum fuel for your vehicle because there will be no ignition retardation causing lower economy.

 

medum, not premium. it rhymed thats why i said it.

no really though, i would do medium quality, the car is pretty old i would start saving money by not using premium ( to buy a S4, ya know) but take the extra performance boost with the better quality.