"Johannes H Andersen" skrev i en meddelelse
> news: snipped-for-privacy@sizefitter.com...
>
> > synt and change at 4k miles. Then I use Shell Optimax petrol which I
> > believe is good for the engine.
>
> "Good" - in what way?
Higher octane and claims to have better quality cleaning additives to keep your injectors working nicely IIRC etc.....
Graham
"Pooh Bear" skrev i en meddelelse news: snipped-for-privacy@hotmail.com...
Higher octane is ok, but about cleaning additives: Shell Optimax is only good for ONE thing: Making money for Shell. ALL petrol has cleaning additives. Shell is only putting 3 times as much in. But for what? Your car is already running very clean...
Cheers!
Higher octane is better. I find that my 9000 CSE LPT will sometimes cut out if I accelerate very hard on regular petrol. But this does not happen with Optimax or other high octane.
Saab's and most other cars run fine on regular unleaded. If you have a high pressure turbo (over ~8psi/.5Bar) then you start needing higher octane. Saab even touts the fact that their turbo cars don't need high octane gas (save Aero/Viggen/HOT).
That may be, but the engine management of Saab turbo cars since APC came in in the mid-80's, will take advantage of octane that you give it. It doesn't _need_ it; you won't damage the engine with low-octane fuel, but you _will_ get more boost (and therefore horsepower) with higher octane fuel. Been that way for Saab for about 20 years now.
"WitchDr" wrote in news:M6idnSCYuIlA snipped-for-privacy@adelphia.com:
Saabs will run on regular, but they aren't as much fun, at least the turbo's aren't. The engine management adjusts to the lower octane by cutting back on the zoom-ability. I run mid-grade around town. Put premium in for long trips or if I'm getting bored.
Well, the car runs fine on regular, but I notice the difference when I push it to the limit of the rev range, though this is only done for curiosity reasons. But then high octane is definitely better. Saab may not need high octane petrol in the sense that the anti-knock system protects the engine.
The nice thing is that it does it automatically. My previous car with a Bosch Motronic engine management had an octane selector uder the hood. You could set it to 85 or 88 RON depending on your choice of fuel.
Graham
Do you have a cite for the *quantity* of additive in Optimax. ISTR that Shell claimed it was using more refined additives with fewer by-products or something similar.
Graham
"Pooh Bear" skrev i en meddelelse news: snipped-for-privacy@hotmail.com...
No, only 6 years of working inside the oil-industry in Denmark. ;o)
Cheers!
It should never "cut-out" due to low octane. It should just drop back to base boost, but that may be what you are feeling.
-Fred W
Have something to add? Share your thoughts — no account required.
Ask the community — no account required