Any reason not to use 89 gas?

[britelzg]

Gas price for 91 is over CAD$1.5/L now in Toronto. So by using 89 can save a little bit and it's listed on the fuel cap. I tried once and didn't notice differences. Any reason not to use 89 but stick with 91? Thanks

[diesel733]

Originally Posted by britelzg

Gas price for 91 is over CAD$1.5/L now in Toronto. So by using 89 can save a little bit and it's listed on the fuel cap. I tried once and didn't notice differences. Any reason not to use 89 but stick with 91? Thanks

You can use 89. You just don't get the full potential of engine at 91. The engine will detune itself to run on 89.

[Manuwai]

Originally Posted by britelzg

Gas price for 91 is over CAD$1.5/L now in Toronto. So by using 89 can save a little bit and it's listed on the fuel cap. I tried once and didn't notice differences. Any reason not to use 89 but stick with 91? Thanks

If it says to use 89, use 89. If it says 91, use 91.

I always fill up at 1/4, which usually costs about $60 USD to fill up with 91.

Doing a quick search of gas prices in Toronto, Shell is $1.54/litre for premium, and $1.44/litre for mid grade.

Full tank in litres is about 85 litres. Filling up at 1/4 tank would be filing about 63.75 litres.

63.75 x $1.54 = $98.175
63.75 x $1.44 = $91.80

$6.375 per fill up doesn't seem like much of a difference to me.

So again, if it says to use 91, use 91. If not, then just use what's recommended.

[maDjzo]

Originally Posted by britelzg

Gas price for 91 is over CAD$1.5/L now in Toronto. So by using 89 can save a little bit and it's listed on the fuel cap. I tried once and didn't notice differences. Any reason not to use 89 but stick with 91? Thanks

Somebody can correct if I'm wrong, using 89 for short periods of time shouldn't be an issue. I've read somewhere that these engines are designed and tuned to a specific timing when it comes to combustion. 89 gas burns faster which might eventually cause pre detonation thus throw off timing and lowering performance and fuel economy. Sensors would limit pre detonation however I myself am unaware if 89 gas will eventually lead to mechanical degradation or maintenance need down the road.

Edit: Typically the difference is minimal in terms of $$. Ultimately imho $6 difference here and there is quite small when we're talking about a $75k truck.

[Qsilver7]

BMW usually gives you a REQUIRED MINIMUM fuel specification...and a RECOMMENDED fuel specification. The owners manual pretty much explains why and what occurs when you decide to use the required minimum vs the recommendation.

The MINIMUM requirement should ALWAYS be fulfilled. The recommendation is your choice...and it will give the performance and fuel consumption numbers that the vehicle was advertised to give etc. Also, the best performance/fuel consumption will probably occur especially if you are an agreessive driver or live/drive in geographical areas that may present challenges (hills/mountains versus flat plains, or elevation above or below sea level). Are you always passing other traffic...or is other traffic always passing you?

If you tend to be a granny-toe driver, are a non agressive driver 98% of the time, live/drive where the terrain is pretty level, etc....then the required fuel specification may work for you vs the recommended fuel spec.

In the end, its your car, your money, and your decision. Only you know how you drive and what your expectations are. As long as you use the required minimum...as stated in the owners manual...it will not affect engine life. How much does performance and response mean to you? It's not about us...but all about you.

[alphaod]

You might save at the pump per fill up, but lower octane gas means retarded timing and often leads to poorer fuel economy.

The result is you might save a couple dollars per fill up, but you end up needing fill up more often, so in the end you didn't really save anything yet you ended up with poorer performance.

[mgbabe]

In Toronto during the summer we fill up with 91 octane. Other times during the year fill up with 89 except on Thursdays when Ultramar sells 91 for same price as 89.

Honestly have not seen a difference. Keep in mind that the oil companies have to meet minimum octane ratings at the pump, but actual can be better.

[andrewmr]

Modern day engine management systems will back the timing up when it senses detonation. This will hurt performance.

However, just running around town at part throttle isn't usually a big deal.

Towing, high temps, hills and mountains all require the highest grade fuel available.

And of course heavy throttle.....

[TheUltimateDrivingManiac]

Originally Posted by britelzg

Gas price for 91 is over CAD$1.5/L now in Toronto. So by using 89 can save a little bit and it's listed on the fuel cap. I tried once and didn't notice differences. Any reason not to use 89 but stick with 91? Thanks

Filled up at 1.38 two days ago at Mobil. Just do your research - station two blocks away can be 10¢ cheaper than your regular one.