mixing diesel and petrol??

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Fri 20 Jan 2006 10:43
mixing diesel and petrol?? - noisytappets
Helo,..my home mechanic mate had a diesel come in which had petrol put in by accident.Not being one to waste fuel -He pumped the petrol out and mixed it with diesel ending up with 70% diesel and 30% petrol.He put it in his 730 petrol bmw and it runs sweeter than it did on petrol so i was wondering what could be a downside to doing this long term?..He is going to try with cooking oil next time>
Thanks for any replies
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Fri 20 Jan 2006 10:48
mixing diesel and petrol?? - Dynamic Dave
From what I understand of your post, he has put a mix of 70% diesel and 30% petrol in his petrol bmw. Not being funny, but it must smoke like a chimney, surely?
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Fri 20 Jan 2006 11:09
mixing diesel and petrol?? - Xileno {P}
It will probably appear smoother due to the lubricity of the diesel. However it must be smoking more than usual and this will affect the cat.

Even if the car appears to run normally, it may not do so for long.
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Fri 20 Jan 2006 11:17
mixing diesel and petrol?? - noisytappets
Good point Dynamic Dave...im gona see him this afternoon so il see what he says..i presume it smokes like one of our public transport buses but HE wont mind that if it means saving a couple of quid! It probly wont see clean petrol till the next mot(emissions)....maybee he will be cleaning the plugs every week!! Il post back when i find out!
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Fri 20 Jan 2006 13:51
mixing diesel and petrol?? - AlanGowdy
Would it be a good idea for all petrol to be supplied with a small percentage of diesel in it to aid upper cylinder lubrication when cold starting? Perhaps not. Interesting notion though.
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Fri 20 Jan 2006 13:59
mixing diesel and petrol?? - Hamsafar
Are you sure you don't mean 70% petrol?
There will be radial cracking around the valve seats in the head if he puts a lot of diesel in it.
It will also smoke, as diesel won't burn properly in a petrol engine, it will come out as partially burned fuel and white diesel vaour.
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Fri 20 Jan 2006 16:18
mixing diesel and petrol?? - noisytappets
Helo,...I wont be seeing my "mystery fuel mix friend" today but il get a more accurate description of what mix he used when i see him.
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Sat 21 Jan 2006 08:53
mixing diesel and petrol?? - Roly93
Are you sure you don't mean 70% petrol?
There will be radial cracking around the valve seats in the
head if he puts a lot of diesel in it.
It will also smoke, as diesel won't burn properly in a
petrol engine, it will come out as partially burned fuel and
white diesel vaour.

>>
I agree with this, no petrol car will run well on a 70/30% petrol diesel mix, and anyone who says they will is kidding themselves ! Years ago I accidently put diesel in my car, and eevn with most of the fuel drained out and topped up with more petrol the car ran very rough, pinking, smoking and gutless. The car didn't run anything like right until another tankfull of pure petrol had gone through. Remember, this much diesel in petrol will have the effect of dramatically lowering the octane rating of the petrol, so I think someone is spinning you a yarn frankly.
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Sat 21 Jan 2006 09:21
mixing diesel and petrol?? - sierraman
After a diesel in the petrol tank incident I ran on a mix,probably 20-25% diesel with no trouble.It was a carburetted car so may have been more tolerant.
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