e10 ethernol blends in old e30 323i

[Madhatter]

still, I'm fairly certain no E30s were ever made that required leaded fuel. they don't have cast iron heads, so hardened valve seats are sort of a no-brainer.

Alloy heads can have soft seats too. I was explaining what his mechanic was talking about. I know for a fact E21's had a bunch of problems with valve wear when swapping to lead replacement fuels, so much more abrasive. Look it up, plenty of people suffering. Fuel companies came out with a bunch of warnings about changing straight to unleaded during this period. Here is an example from shell.

http://s04.static-shell.com/content/dam/shell/static/zaf/downloads/products-services/compatibility-chart.pdf

I said I would suggest the seats will be fine and you don't have to worry, but you need to run the right octane fuel. Telling the guy no E30 ever needed leaded fuel is just plain wrong. This car was sold and delivered here running on leaded fuel, the same as it was in the UK, sometimes you guys in the US fail to account that it is different across many overseas countries. If it wasn't, the OP wouldn't be in here asking is it a problem to run unleaded when it was previously a leaded car.

So, as I said, you just need to make sure you run a minimum 95 octane fuel because of the added compression ratio of the motor. It will ping and can suffer significant engine damage if you don't.

Edit: Just in case I still haven't made it clear enough. Im making the point that it was designed to run on a fuel here with a much higher octane rating (leaded), and it's this part of leaded fuel that is the bigger problem, not worrying about valve wear. I don't even remember seeing unleaded fuels here as a kid in the 80's. Just leaded, diesel and gas. I don't think it was until the late 80's, maybe early 90's that you started to see it at all service stations. Prior to that, everyone just ran leaded fuels, it used to just be called "super". Don't think it was even officially (ie before that you couldn't buy it anywhere in australia) made available until 1986, even new cars produced here prior to this ran on leaded.

[lentildude]

thanks for all the comments from everyone, many opinions. Thanks Madhatter for your local perspective/experience.

I have 1/2 tank of e10 (octane 91) left. Might fill the other half with either proper 95 or even thinking of high octane 97. The 97 might bring up the 1/2 tank of e10 to an average of 95?? Guessing mixing all these fuels isnt a good idea either.
(been getting crappy fuel economy on e10, about 6-8km/litre on highway)

BTW- Shell(Coles) e10 is 94. Is 94 close enough to the reqd 95 to run safely in the e30?
Caltex e10 (Woolworths) is octane 91

"Shell Unleaded E10 has a minimum 94 octane rating, much higher than the Federal Government mandated minimum of 91 octane for regular unleaded fuels. If your car requires a fuel with a minimum 95 octane rating, we recommend you use Shell Unleaded 95"

[nrubenstein]

One thing that continually causes confusion is that octane is measured differently in the US vs. most of the rest of the world. 87 AKI US regular is roughly equivalent to 91-92 RON in the rest of the world. Likewise, 93 AKI US premium is roughly comparable to 98 RON in the rest of the world.