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Adding Oil to Diesel Fuel

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by d215yq, Jan 16, 2020.

  1. d215yq

    d215yq Senior Member

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    Hi All,

    As I have an old diesel and do pretty much exclusively long journeys (50 miles +) and live in a warmer climate I was experimenting over summer with up to 40% sunflower oil mixed with diesel, particularly when out of Spain where the price difference is 60%. In general mpg was not affected and the car smoked less and ran smoother, something that apparently is normal so all good

    Now it's winter, and especially given only 4 of 6 glow plugs work I have stopped using the veg oil and been putting pure diesel in. However, my father also has 15L of 15yr old 15W/50 oil which is too old (I presume) to use as actual engine oil which I collected from home so I've been adding 1L in with some tank fills when I can be bothered....I'm not sure if it's a placebo affect but instead of make it run worse as I thought it might it seems to make the car idle smoother and the car quieten down a bit, and hasn't made the car harder to start/smoke at all.

    I've heard on here people putting 2 stroke oil in diesel and saying it makes it run better (I have no idea what 2 stroke oil is) but would normal motor oil have the same/similar affect?

    By the way, no need for the "I'd only use pump diesel, it's a false economy, sounds like a fuss for not much gain" type comments, i just want to know the technical side of how it works, pros and cons as I find it all interesting. My use of veg oil, oil and 200L of free diesel I got given with some water in it has already saved me the value of the car and with zero problems so far. Besides, I hate wasting things so if they can be used to get the car a few extra miles then it is something I like to do even if the cost saving is negligible.
     
    Last edited: Jan 16, 2020
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  2. rf065

    rf065 Senior Member

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    The diesel engine was originally designed to run on peanut oil. Is that expensive these days?
     
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  3. Wighty

    Wighty Senior Member

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    I add a mix of 2 stroke mineral oil and cetane to my E320cdi . I use an old redex bottle to get it in the car .
    Roughly 150ml of 2T Oil and 100ml Cetane
     
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  4. js190d

    js190d Senior Member

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    Your Mercedes:
    1991 w201 190d 2.5/ 2002 s210 320cdi avantgarde
    The 5 cylinder om 602 in my w201 190d 2.5 also runs smoother (quieter at idle) on veg oil compared with pump diesel. During the summer time i used 100% veg oil (either new from supermarket when sub £1 per litre) or WVO (waste Veg oil) collected by me from local hotels.

    I would have thought during the heat of a spanish summer 100% veg would be perfect.

    I used a filter bag from this chap on ebay to process the used veg oil. Just pour it in and out comes lovely clear fuel! Magic!

    https://www.ebay.co.uk/usr/filterbagman2

    Never used engine oil but have read of people even using filtered used engine oil so as long as your new oil is not really thick then should be ok.

    My advice would be to always carry spare fuel filters with you, and especially the small in line fuel filter which on my car is below the air box.

    I have also changed the glow plugs on my car (not that difficult if you have flex joint socket set) and would say it would be a good idea to make sure all of yours work if you are going to use alternative fuels during the winter.

    Also check if the injection pump seals are not weeping, again not difficult to fix with parts from mercedes dealer being about £15.

    One top tip i used if i was going on a long journey was to start the car on diesel, get it up to temperature and then add veg oil to avoid start up problems in cold weather.

    Also the Bosch injection pumps on these old engines are lubricated by the engine oil not the diesel itself which is one of the reasons all bosch pumped indirect diesel engined cars (like some pug 205's) are perfect for non fossil fuels.
     
    Last edited: Jan 16, 2020
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  5. OP
    d215yq

    d215yq Senior Member

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    Thanks, that's good to know. Though I'm not too fussed about running it on Veg Oil in winter here in Spain as I can get pump diesel for 1,11 and veg oil is 0,95. And as it's a lot more hassle filling up this way I'd never do 100% even in summer. I'll carry on with the oil until that's used up and when we get to April so 20 degrees minimum starting temp I'll go abck to adding veg oil when I can be bothered... Though it's more when driving to France/UK that it makes a difference in the price and then by definition it's doing very long journeys!

    I am planning to add in the old engine oil when I next do a change as here they only recycle it 2L at a time so that's 4 trips so it would actually be easier to dispose of by filtering and chucking in the tank 2L at a time! Greener than 4x trips or just chucking it in the bin like most would do...
     
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  6. OP
    d215yq

    d215yq Senior Member

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    I can't find 2 stroke oil here in Spain nor anything to translate it to. Does it have a more technical name perhaps that I could translate...how is it different to normal motor oil for 4 stroke engines?
     
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  7. js190d

    js190d Senior Member

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    The only thing i would be wary of is used engine oil as it may contain metal particles and people who have recycled it for a fuel had to use a centrifuge to seperate these particles so may not be worth the risk on that point alone. Personally i would not use old engine oil as a fuel.
    Heating oil or kerosene however...
     
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  8. Blobcat

    Blobcat Moderator

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    Cepsa moto 2t, is what you’re looking for. All those mopeds running around use it
     
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  9. Wighty

    Wighty Senior Member

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    As @Blobcat says , all the small scooters are probably on it , as well as small garden machinery . It’s 2 stroke if you add it to fuel like in a chainsaw or garden strimmer
     
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  10. SL55 Mark

    SL55 Mark Senior Member

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    Very illegal in the UK, but would work fine in some older diesels (or so I’ve heard). I have never tried this, as to do so would incur a serious fine, plus confiscation of vehicle, and the old bill are pretty hot on it round here.
     
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  11. sonic

    sonic Senior Member

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    Go to a motorbike shop they will have loads.
     
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  12. sonic

    sonic Senior Member

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    Its a VOSA offence now.
     
  13. sonic

    sonic Senior Member

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    Back in the late 60's the army 4 ton truck went diesel, & we used them in Bavaria skiing. They were fitted with either starts but the capsules were like gold dust. We found putting 20 Ltrs of kero (paraffin) in tank full of diesel, improved starting. Just left a white trail of smoke.
     
  14. NBurns

    NBurns Senior Member

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    So in summary what are you using to fuel your old Mercedes-Benz?



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  15. NBurns

    NBurns Senior Member

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    Oh!!! okay. Now I'm even more interested.


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  16. NBurns

    NBurns Senior Member

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    Okay, that was very interesting reading. So in summary what can we use Legally to fuel say a 2005 C220 CDI Classic SE, S203.208 (Estate), OM646.963 Engine ? Could I save on my fuel costs if I changed my strategy/fuel from diesel?



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  17. 00slk

    00slk Senior Member

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    Plus it'll make the 55 run poorly ;) :rolleyes:
     
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  18. OP
    d215yq

    d215yq Senior Member

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    The thread is talking about two things:

    1) adding oil/2stroke/cetane/other oil based products to make it run better and not save money as these are actually more expensive than fuel unless you have some knocking around. You can use these on your cdi

    2) using veg oil based products as they are cheaper than oil based ones - those are not recommended on a cdi as i believe the high pressure changes the composition. I have an old diesel which is not common rail/high pressure.
     
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  19. NBurns

    NBurns Senior Member

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    Ah. Thank you for that clarification d215yq.



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  20. OP
    d215yq

    d215yq Senior Member

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    Your Mercedes:
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    majority pump diesel (cheapest supermarket stuff available)
    a few litres here and there of motor oil as i have some to use up
    veg oil when it's warm and i can be bothered/moreso when in UK/France where diesel is more expensive
    as a one off i got 200L of watery diesel free from an unknown source which i left to settle and used the best 80% of

    It's not about "old" or "new" MB though. Yours is a CDi mine is a Indirect injection and that makes mine much more flexible for different fuels
     

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