PKSlice

Will this mess up sensors and wreck the engine, or just lower the performance?

ItalianJoe1

The car will run normal but may suffer from detonation on quick throttle transistions before the ME can react. Why do you need to run regular fuel?

insame1

If I were you I would do some research on octane and why there are different grades . Then make the dissension based on facts not opinions on a forum. The truth is they don't tell you to use premium because MB has a collusion with big oil.

PKSlice

Reason for considering regular octane is that in Toronto premium gas is $4.70 / gallon $$$

betrezra

I bet you could get the delta cost savings between premium and regular with driving style only.

If i drive like an aarp person can eake 50% better mlg. Then if the mood over comes you the high oct fuel is in your tank if you want hammer it!

Gl

GatorMB

I dont think anyone does not hammer it once in a while.

The NA55 is near 11:0 to 1 Compression ratio which requires proper fuel.

The tuning on this engine is not compatible with the amplitude or variation of fuel quality. Best to stick with what it requires.

A colder spark plug heat range will reduce detonation but also reduce the life of the plug and iridium is not as cheap as a fresh tank of ethyl.

2cents, Gator

PKSlice

Think I will stick with premium and just hammer it on special occasions, otherwise I don't rush to those red lights only to hit the brakes. I don't understand why people do that.

tw2

Same reason people think that cruising at light throttle is the most economical way to drive despite making the engine work against the highest vacuum possible.

C3Duece

sensors will be fine but the ecu will pull timing under heavy load to avoid detonation so performance will suffer.

otakki

Performance will suffer but otherwise there shouldn't be permanent damage to the engine. Just remember some localities have no gas with the minimum recommended octane. Certainly car makers don't expect avoiding regular gas if running low on fuel at those places.

MarcusF

As posted earlier, the ECU will retard the timing when it detects pinging (resulting in bad fuel economy and flushing any "price of fuel savings" down the exhaust port), but the timing doesn't stay retarded. The ECU slowly starts bringing the timing back to stock specs until it pings again. At that point it retards the timing and starts bringing it back again. This"retard and adjust until a ping is detected" dance will continue as long as substandard fuel is running through the system. The thing that some people miss is, the engine is pinging. It's not pinging as frequently as it would if the ECU wasn't repeatedly backing the timing off, but it is pinging. Pinging is horrifically bad for engines.

tw2

I agree completely. The engine is technically experiencing minute damage in the form of added heat and stress on components when this happens. I was under the impression that the knock sensors are generally very sensitive and fine tuned to detect very subtle changes well before any huge stressors are encountered such that low octane fuels could be run for a long time without destroying an engine. I run 98 RON which is the highest I can get at a standard commercial gas station. In some regions 95 RON is the highest and car manufacturers have to account for this.

insame1

95 RON is the equivalent of 91 oct here in the states (the highest you can get in CA) and they sell as lows as 87 oct here which is the equivalent of 91 RON. I would not risk putting 87oct gas in my car.

GatorMB

I have been trying to understand this as well, It is really easy to investigate though. I work at night and sometimes weekends. While I am driving to work others are off. When I drive home they are going to work.

I find that people in commute to work or friday anytime are eager excited and in a general hurry or frustrated with light to light traffic.

Often people are at their best on the way to work unless its raining or icey cold. but really slow. The fast find trees and power poles comforting.

On the weekends its a toss up, either excited, relaxed or drunk. All good for an accident.

It is best to blast off when no one else is near and never in a resident community.

Cheers