bmwe21.net forums

Hi everyone,
Im looking for the right answer to what type of fuel I should be using in my car. I have a 1983 316(1.8 m10) E21 and have been told I can run it on unleaded with no problems by a BMW specialist but the manual and Haynes manual say it needs leaded. Don't know whether to start putting super unleaded in her, continue with unleaded and that will be alright or do I need to get it converted to run on unleaded. Any advice would help. Thanks guys.
Joe

The basis is that all original E21 valves and valve seats are not designed to cope with unleaded fuel. However, there is a press release from BMW that says that if cars have been running on leaded fuels for 50+ K kms, which will be the case at least with 99% of the cars run in Europe, there is enough lead sediment to be able to drive on unleaded these days.

So unleaded should do in most cases, but it may be good to fuel her up with leaded or use a lead replacement additive once in a while.

Another issue is the octane count. Many of our engines were designed to run on an octane count of 95 or even 98 back then. In most cases you will be ok these days, but if the engine is running lean and the ignition timing is not 100% up to par, there is a chance of pinging, which you may be able to hear running the car under load at lower revs.

Thats great. Thankyou ever so much for that.
All the best
Joe

I have been told from FritzBits that all BMW engines from 1973 on, can run on unleaded fuel with no problem at all, and they did not mention any need of filling with leaded fuel or replacement once in a while. Did they mean that all this is due to the km that all these engines have done? Most probably, although on the first place I thought I understood that these engines had already this technology. Quoting their reply: "....You can run unleaded petrol in all BMW engines after 1973, including yours."
Actually, I have been running on unleaded a lot recently, (185000 km) with no problems at all. However, whenever I find the -more rare than before, it is true- LRP, I enter the gas station to fill her up...)

Correct, that's because they have been used on leaded fuel before. I have that press statement from BMW somewhere, but where?

Thats good. My car only has 60,000 genuine miles on it, I know the previous owner only used unleaded and he bought the car with about thirty thousand on the clock so ill put some additive in every now and then as it may not have had much leaded in its life but by the sounds of it unleaded wont do much harm. Good news really

Sorry for necroing, but posting anyway to say thanks to previous posters for the useful answers.

Bought myself a 320/6 yesterday and came here with the same question as OP. Now I'm at ease about filling it up with (premium) unleaded

you're welcome

and congrats with your new buy, hope we can see it in the registry soon!

For what a bottle of addative costs id use it anyway.


Back in the early 90's i had my 323 retuned by bmw to unleaded.
It was awful,
Full of flap-spots & eventually burnt the valves out which leas it go to the scrapyard
Black 323i with recaro interior and zender bodykit .......

I ran my e21 320 on unleaded back in the 80's! Had the timing adjusted to run unleaded and I didn't notice any diference except it went bettor on higher octane fuel. No problems with valves burning but a set of plugs only lasted 6000 miles!

If you are worried about valve seat recession, suggest you occasionally check valve clearances, as they will close if recession occurs.
I've set mine slightly tight at around 8 thou, as they were noisy at 10 thou.
Shame we can't get leaded, old engines seem to run much smoother with it.
Mike