clear this up for me once and for all please don

[hookahawg]

i read the FAQs section and am aware that all standard optis need 87 octane MINIMUM.
given that, is it better for the engine to run high octane, will it strain or damage it, or is it of no benefit at all?

thank you as usual.

[EuropeanAM]

For STANDARD Optimax engines, Regular Pump Fuel (87 Octane) is recommended.

Mid-grade would be an acceptable alternative.

Anything higher than mid-grade (89 octane) is a waste of your money.... especially when you consider that higher octane fuels burn SLOWER AND COOLER (actually, they can rob your engine of performance, and contribute to carbon deposits).

[gambler1]

Not to hijack, but my 04 250xs requires min. 91 oct. could I run 89 or 90 in a pinch? the reason I ask is at some marinas where I go they usually offer (non- ethanol gas) but it's not 91. Could this rob me of performance or worse yet an engine failure?

[hookahawg]

thank you again sir

[EuropeanAM]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by gambler1 &raquo;</td></tr><tr><td class="quote">Not to hijack, but my 04 250xs requires min. 91 oct. could I run 89 or 90 in a pinch? the reason I ask is at some marinas where I go they usually offer (non- ethanol gas) but it's not 91. Could this rob me of performance or worse yet an engine failure? </td></tr></table>

Your engine is a completely different scenario. Under NO CIRCUMSTANCES should you operate your engine with LESS than the recommended MINIMUM OCTANE RATING.

[gambler1]

Thanks Don, I just wondered what would happen if I did use the lower octane. I've always used at least 91

[Oldgeezer]

Hi Don-Question about octane additives that will raise the octane a number of "points". In a "pinch", are these additives acceptable to use without negative affects? Just recently was on vacation and made the mistake of running the fuel level down to a point of being not able to get to the next station on the water with a 93 premium that is required for my XB 250. I took the chance of putting 7 gallons of 89 octane with my remaining 7 gallons of 93 octane figuring that the result would equal 91. I further added an octane "adder" that would raise the octane a "few" points. Bottom line. Did not have problems(Did not beat on the motor by the way) with any negative effects. Not recommended, but could I do this again in a pinch if I HAD ANOTHER BRAIN DRAIN AGAIN? Thanks for your input.

[EuropeanAM]

I think I know what you're asking about.

I've not tested the product, but as we both know... it has been tested by several reliable sources right here on BBC. I can't argue with their results (their applications are far more demanding than yours).

That being said... we've talked about running "too high" of an octane in your engine (higher octane fuels burn slower and cooler).

In a PINCH (especially where your engine REQUIRES 91 minimum octane fuel)... you're better off to play it safe by bolstering the octane (as opposed to running too low an octane).

This is a TRICKY business.... and I would not recommend making an "everyday thing" of octane level "estimating". Plan to purchase the appropriate octane fuel...