what grade fuel do you use

Hi folks,

Stand back because I'm opening a can of worms here on a topic that many are more passionate about than religion!

What octane is best for a 1989 (motronic v1.3) 325i?

The choices here in Australia are 10% ethanol (no way!!!), standard 91, premium 95 and ultimate 98. I'm that there is perhaps an increase in mileage, power and general engine happiness in going 95 over 91, but since the M20 engine doesn't have knock sensors the engine can't adjust for the increased octane of 98, so there won't be much benefit over 95 and it may even be worse somehow.

But then again, the petrol companies always rant about how the detergents in the 98 clean your engine to keep it running well. Then again, a mechanic friend has recommended using some combustion chamber cleaner when I service it next so I could do that instead...

I'm happy to pay a bit extra for better performance and engine longevity, even if the extra mileage doesn't cover the cost of buying fancy petrols, but from the seat-of-the-pants I haven't noticed any difference between fuels so far.

What do you think?

Cheers,
Simon

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nomis3613
Hi folks,

Stand back because I'm opening a can of worms here on a topic that many are more passionate about than religion!

What octane is best for a 1989 (motronic v1.3) 325i?

The choices here in Australia are 10% ethanol (no way!!!), standard 91, premium 95 and ultimate 98. I'm that there is perhaps an increase in mileage, power and general engine happiness in going 95 over 91, but since the M20 engine doesn't have knock sensors the engine can't adjust for the increased octane of 98, so there won't be much benefit over 95 and it may even be worse somehow.

But then again, the petrol companies always rant about how the detergents in the 98 clean your engine to keep it running well. Then again, a mechanic friend has recommended using some combustion chamber cleaner when I service it next so I could do that instead...

I'm happy to pay a bit extra for better performance and engine longevity, even if the extra mileage doesn't cover the cost of buying fancy petrols, but from the seat-of-the-pants I haven't noticed any difference between fuels so far.

What do you think?

Cheers,
Simon

I think that if you have some extra money and you want to get rid of it by burning it, 98 octane is the right choice for you. If you want to buy the least expensive fuel your car will run right on, buy the 91. I use 89 (US rating, I think that's the same as your 91) and it's fine. I even get the stuff with ethanol sometimes. All that engine cleaning stuff is pure hype too. Once upon a time I wasted a lot of money buying expensive name brand fuel for my VW bus. When it came time for a rebuild, I was surprised to see the most crap built up on my valves I had ever seen in an engine. Buy the cheapest, lowest octane fuel that doesn't knock in your engine. Anything more is just a waste of money.

John

i've always used 91+

Buy what the owners manual says is the proper fuel...you only need premium if you have a performance chip!

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John Yust
I use 89
John

D'oh! I mean 87. The cheap stuff. That's what I meant to type. No knocking at all, even under hard acceleration up hills. My car is an '87 325, which is an eta.

John

Please, correct me if I'm wrong, for I am too young to have cared at the time.

It seems I remember a comment on the old BEN that when our car was produced (87-91) that there was no mass produced octane higher than 87 or 89 for vehicles. Thus BMW designed the engine for that grade, and nothing more.

Now, I don't know if that only applies to a specific country, or if the age of an engine would shift the octane level that it is "tuned" for.

Thoughts on this from someone who was actually driving a car in 87? :-)

I've been driving about 30 years and I can't think of a time there wasn't a premium grade @ 91.

I can remember when you had a choice between unleaded and regular. Those were the good old days when the environment didn't matter! B)-

I remember all of those years also. I was driving a 1984 318i through 84 to 88 and then acquired my present '88 325is in 1988. it has always run fine with 87 octane, but in the summer i would use the 89 octane because of the higher temperatures.

I believe that the Australians use the research octane numbers which are higher than the North Americian R+M octane numbers, so I would use the 91 octane for the car in australia. Just use some injector cleaner every once in a while and you will be fine. I a approaching 670,000 kms on my M20 and it still pulls strongly.
Salut, Bob P.

Hi,
Thanks for replies. I'll be happy to stick to regular unleaded (equivalent of 89 octane) and save the cash for projects on the car!

Simon

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wodcutr
I can remember when you had a choice between unleaded and regular. Those were the good old days when the environment didn't matter! B)-

Oh, pain me not with these words. If you cut me, do I not bleed?

I, too, am guilty of a CO2 footprint larger than I should have - precious Beemie as the primary cause.

Why does the thing I love so much cause such internal conflict? (Was it ever such?)

A close friend of mine likes to borrow the Beemie. I like to flatter myself by thinking that she borrows it because of its awesome Beemie-ness rather than the simple desire to save money. (Uhh - the Beemie has a VERY short list of approved drivers at this time - me and one person whom I seriously would trust with my life if the situation arose which is strangely comforting thought.Sometimes "the Brother" drives too. )

Be well, Kelly :-)

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Kelly

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wodcutr
I can remember when you had a choice between unleaded and regular. Those were the good old days when the environment didn't matter! B)-

Oh, pain me not with these words. If you cut me, do I not bleed?

I, too, am guilty of a CO2 footprint larger than I should have - precious Beemie as the primary cause.

Why does the thing I love so much cause such internal conflict? (Was it ever such?)

A close friend of mine likes to borrow the Beemie. I like to flatter myself by thinking that she borrows it because of its awesome Beemie-ness rather than the simple desire to save money. (Uhh - the Beemie has a VERY short list of approved drivers at this time - me and one person whom I seriously would trust with my life if the situation arose which is strangely comforting thought.Sometimes "the Brother" drives too. )

Be well, Kelly :-)

These days, as carbon footprints go, I don't think the M20 is all that bad.

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rkj
These days, as carbon footprints go, I don't think the M20 is all that bad.

i dont think any bmw motor is that bad, save for maybe the v12s. even they are efficient in their own right.

Supposedly the new BMW Diesel's exhaust is cleaner than the air going into the intake in LA. :embarrassed:

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Andy 90 325i
Supposedly the new BMW Diesel's exhaust is cleaner than the air going into the intake in LA. :embarrassed:

You say that like it means something

But really, that's a pretty interesting little tidbit.
So the obvious conclusion to draw from this is, in order to solve LA's pollution problem people in LA need to buy more Diesel BMW's

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Andy 90 325i
Supposedly the new BMW Diesel's exhaust is cleaner than the air going into the intake in LA. :embarrassed:

That is only true if CO2 is not considered 'dirty'. The exhaust of the diesel will contain more CO2 than the combustion air.

The exhaust will, however, contain less NOx than the injested air because of the urea injected into the exhaust. Diesel reactions produces more NOx than the gasoline engine due to the higher reaction temperatures and gas recirculation isn't sufficient to mitigate this effect, hence the necessity to further treat the exhaust with urea, effectively eliminating the NOx.

Salut, Bob P.

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Bob P 325is 88

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Andy 90 325i
Supposedly the new BMW Diesel's exhaust is cleaner than the air going into the intake in LA. :embarrassed:

That is only true if CO2 is not considered 'dirty'. The exhaust of the diesel will contain more CO2 than the combustion air.

The exhaust will, however, contain less NOx than the injested air because of the urea injected into the exhaust. Diesel reactions produces more NOx than the gasoline engine due to the higher reaction temperatures and gas recirculation isn't sufficient to mitigate this effect, hence the necessity to further treat the exhaust with urea, effectively eliminating the NOx.

Salut, Bob P.

Wasn't the new (clean diesels) having trouble running on our fuels here Bob, something about the sulfur content or lack of?

Wasn't the new (clean diesels) having trouble running on our fuels here Bob, something about the sulfur content or lack of?[/quote]

Yes! But now the refiners have installed the equipment to handle the sulphur. BTW, that is also a reason that North America relies so much on the 'sweet' inported oil - the lower sulphur content.

Salut, Bob P.

I drive a 87 325 and also run on regular with out a chip, and premium with the chip.

I like that California pasted such restrictive epa regulations on diesels that MBZ could not bring in their new Bluetech into the states, but Ford and Chevy can build their trucks with no regulations. The real kicker is the US goverment and CAFE, [www.terrapass.com] (a little article about CAFE).

______________________________________________
87 325e

Still trying to work smart not hard.