i heard that if you fill your car up with supreme unleaded that it is bad to put regular back in?

Question

i own a volkswagon gti vr6

Answer 1

Thats all bs! If the your engine doesn't have high compression where supreme fuel is needed, your engine won't know the difference. The higher grade fuel only means that the octane rating is higher so the fuel can withstand higher compression. It isn't cleaner, nor does it have more energy per unit mass than lower grade fuel.

The only time you use a higher octane fuel to "clean" the engine is when you use ethanol. The alcohol will clean debris and build-up in the fuel tank and lines. It is not the higher octane that represents how "clean" the fuel is.

One person said that the car develops a memory of having higher octane fuel. Also incorrect. Because he got the advice from a mechanic means nothing. I know mechanics that don't crap. Like I said before, without higher compression, the engine doesn't know the difference between regular and higher grade fuels.

Van_Crackin is also incorrect. If an engine requires higher grade fuel, regular fuel will cause the fuel/air mixture in the engine to combust via compression rather than the ignition spark. This is called "knocking".

Answer 2

That's utter rubbish mate.

First of all as some people have mentioned, you can look in your manual and see what is mentioned in there, but more often than not the octane rating is given inside the fuel filler flap. On my car the manual just mentions unleaded whereas in the fuel flap it states 98 RON unleaded ( i.e. Super unleaded ) and this is actually more accurate than the manual.

Also as some contributors have mentioned the car develops a "memory". This is actually due to the ECU on most modern day cars. The ECU tries to fine tune the engine management to obtain the best state of running. It might take a couple of hundred miles to achieve this.

I run Shell Optimax quite regularly and I can feel an improvement in engine response, engine smoothness and more miles to the gallon, also I feel and hope that as Shell alledge, it does the engine good. In previous cars I tried Super Unleaded Vs. 95 RON Unleaded and the only difference I could see was a bigger hole in my pocket, so then I didn't bother.

Answer 3

no, you can fill up with 93 then 87 then 89 then 93 then 87 and all it will do is either give you a hint more power or a hint less power and some valve knocking.

octane in gas is there for how the engine is designed. a car such as a GM or Ford, the valves are farther apart and can handle a lower grade fuel, where a higher end car, a Lexus or BMW require premium cause the valves are closer and need that extra octane to function properly.

use what your car requires, anything above this is a waste and anything below this can cause damage over time. if your car takes premium but the prices hurt the pocket book, you can put in 87 octane and then 2 bottles of STP cleaner to the tank. its cheaper per tank up but it gives the same 93 octane.

Answer 4

If you fill up with supreme unleaded once in a great while it's no big deal. The problem comes when you use a higher grade of gasoline on a regular basis. What happens is your car develops a "memory" to the higher grade and then won't run worth a darn on anything less. Got this advice straight from an engine mechanic: If your car starts running rough, wait until you get low on gas and then put a bottle of Valvoline Fuel Injector Cleaner in and fill up with supreme unleaded. That has worked for my car. I do it about twice a year, and the rest of the time I just put regular unleaded in the tank.

Answer 5

No, you will be fine putting unleaded back then.

Let me let you in on a little secret, premium fuels are a waste of money. Any expieranced mechanic worth his salt will tell they do next to NOTHIN but put a hole in your wallet.
Even high performance cars that "need" premium fuels can be run just fine on unleaded.

Answer 6

That's nonsense. If your owner manual indicates regular unleaded then that's what you should use. Premium, when it isn't needed, is a waste of money. You are not going to damage the car in the scenario that you describe.

Answer 7

putting large in it won't make the vehicle bypass swifter get greater MPG or harm it IF the vehicle is working correct. some human beings's automobiles do run greater applicable with large (if it calls for prevalent) purely becasue the engine or working device is off..

Answer 8

Wrong, Don't believe anything your friends tell you. Check your owners manual or ask a dealership if you need proof.

Answer 9

its accually good to run super once and a whilekeeps carb clean ,,and you can put reg no prob