Hello

Have you tried?

I think os great!

FreeMac

 

Optimax is still the best on the marked IMO, it has the highest octane rating if you combine RON and MON.
The important figure is MON which is resistance to detting under high engine speed, and Optimax still has the highest of any pump fuel in the UK.

In the UK they seem to state RON at the pumps, but the Americans state the octane rating which is RON + MON x 0.5.

Dipster.

 

OK.............. What is MON
Never heard of this.

Paul

 

I thought it was the day before TUE

 

Nah, he's a mate of RON's!

 

seriously what is MON, im about to buy a 1994 WRX and am a bit concerned if i can run on SUL or if it has to be optimax all the time.

Also ive heard that the scoob has a light to tell you if its detting???????????

 

OPTIMAX = More performance
ULTIMATE = Smoother
LPR = Less performance and less smooth
DIESEL = Engine Failure
2 STROKE = Smells nice
LPG = Oooops
RED DIESEL - Engine and brain failure
JET ENGINE FUEL - Not required - have scooby
SUNFLOWER OIL - HMMM CHIPS

So take ya pick - personally I like Ultimate and Optimax as much as each other but for different reasons. Plus there's a garage for each on my way to work...

Dont know abooot the light on the dash - never seen it folks!!!!

P

 

I run on Optimax but sometimes struggle to find a Shell, how or what be the out come if I mixed it with BP Ultimate.

 

Here we are...

<snip>
The motor octane rating, referred to as MON (motor octane number), is the best rating to use when selecting fuel for your race or high compression engine. When testing MON, the fuel is heated to 300° F and the intake air is heated to 100° F. The test engine is a single cylinder 4 cycle engine that is run at 900 rpm. Ignition timing is varied with compression ratio. Engine load is varied during test.

RON (research octane rating), this is what our pumps quote. The testing is done at 600 rpm with a fixed timing of 13° BTDC. The fuel temp is not controlled at all and the intake air temp is varied with barometric pressure. This is done to covert everything to a SAE standard day, which is 60° F, 0% Humidity, and 29.92 inches barometric pressure. The RON should not be used when selecting fuel for a race or high performance engine. The RON will always be higher than the MON.

Our American friends use the RON + MON x 0.5 Rating at there pumps not RON. It is average of the RON and MON. It is ok to use this for lower compression street motors, but when you get much over 10:1, you should really pay attention to the MON. The closer the RON is to the MON, the more stable the fuel is. This can be very critical when running 7000+ rpm.
<snip>

So a high MON combined with a high RON is very good and Optimax has both.

Dipster

 

Nice Reply from Dipster

Dave