BMW Werkz banner

325es, what grade petrol?

3K views 20 replies 11 participants last post by  gotKRAUT 
#1 ·
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!
 
#2 ·
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.
 
#4 ·
i own a 1991 318is i use 89 for fun...iono if thats good or bad or wasteful? anyone?
 
#6 ·
how does that octane boost work? you just add some amount to your normal gas and it raises the octane in it?
 
#9 ·
ahh tricky...ok thanks for the tips fellas much appriciated :D
 
#12 ·
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.
 
#13 ·
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.
 
#17 ·
As well as we can at any track related pump station. But we are not hampered by your CARB yet. Our cars just have to meet your states emission levels which is good. I like clean air. I was just stating that in US there are places where octane is higher than 92 I saw 95 in CT the other day at a Sunoco station but would never pay $2.55 a gallon for it when 94 octane is available in town for $1.85.
 
#18 ·
i like clean air too haha...thats why i drive my carb'd veedub once a month if that...usually at the track too...but i agree too expensive...man 94 octane for 1.85....i just paid 1.97 for 89 today(cheapest in town)....i hate you lol
 
#21 ·
Originally posted by Old_School_Bimmer@Sep 10 2004, 06:43 PM
i think sunnoco has like 94 octane i always put it and if u say there is no difference in perfromance then u are probably high on somthing and also try z max i like that stuff
z max :rock
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top