325es, what grade petrol?

[baram23]

Hi -

I recently took ownership of a 325es, 210k miles on it, seems to run well but I have a couple of questions.

The previous owner didn't have service records or the bmw owners manual for the 3 series, so 1st thing I'm wondering is which grade of gas makes the most sense? I have available to me - 87, 89 and 91. I have been using 91 since I don't know what is best for the engine. I don't have any performance chip or anything of that nature installed, and I probably won't put one in until I've sorted out any other outstanding issues with the car if I do it at all.

Second thing is that there is a high pitched whine when i'm running in 4th or 5th gear between 2000 - 3000rpm, if i turn the wheel or stop accellerating and let the car coast it seems to go away.

Anyone have any idea what this could be and whether the repair will be something that has to happen quick, is it expensive and can it wait awhile?

Thanks!

[Aether]

Typically, higher octane is just going to be better for your engine. But 87 should be just fine - BMWs aren't nearly as fussy about gasoline as they are with oil. I put 93-94 in mine, just because I like to show off, but there's probably no detectable difference in performance, emissions, or wear between 89 and 102 racing fuel.

[MrM3]

your car was made to take 87, but e36's, e34's (1990-on), and newer bimmers need at least 91

[BMW Lover]

i own a 1991 318is i use 89 for fun...iono if thats good or bad or wasteful? anyone?

[gotKRAUT]

i run 92 24/7 in mine...motor just runs smoother and pings less...but then again it had a JC chip which required 92 so :P most of the time i had octane boost too...

[BMW Lover]

how does that octane boost work? you just add some amount to your normal gas and it raises the octane in it?

[Aether]

Originally posted by Slvr E30iS@Sep 8 2004, 01:18 AM
you just add some amount to your normal gas and it raises the octane in it?

Yes, exacty.

[Bear]

On Octane booseter, read the label and fine print carefully. What seems to be a 4 point increase may be .04 percent increase.

[BMW Lover]

ahh tricky...ok thanks for the tips fellas much appriciated

[sixcylinderuk]

My 320i will run on any octane rating from 91 up.I always use the UK standard 95 octane but I've wondered about trying Shell Optimax which is 98 and BP do a similar brew but I think it may only be 97.You can still get leaded here but it's more expensive and would not benefit my engine.

[takaaco]

what did you mean fussy about oil what grade do you recommend

i have been using 20-50 because i drive it like i stole everyday

[Aether]

Right, I use 20-50 synthetic.
Like most things, BMW's idiosyncyacies have become more pronounced over time - the E46, for instance, comes with like three quarts of the oil you're supposed to use in it, and that's like the only kind. You can probably get away with other stuff, though.

[PMB]

Now, according to my workshop manual which covers all 3-series engines back to 1991, the 4 cyl. engines should be run on unleaded 95 RON fuel. Fuels as low as 91RON may be used too but will reduce performance. For 6 cyl engines 98RON is standard but 95 RON may be used (again with reduced performance). Lower octane fuel also reduces fuel economy slightly.

In my experience I can tell no difference in neither perfoemance nor fuel economy between 95 and 98 RON in my 328.

On my Yamaha 250 the difference is huge I guess it just does not transpire to the car which is nearly 10 times the weight.

[gotKRAUT]

umm in the US 92 is as high as it goes buddy heh :P

[M-technik-3]

Originally posted by BMDubya84@Sep 10 2004, 10:33 AM
umm in the US 92 is as high as it goes buddy heh :P

Not true. East Coast gets Sunoco 94 ultra. And in EU the use differant standards as to the formula for figuring out Octane ratings.