Oil/Diesel Mix for better fuel economy

Submitted: Friday, Jun 16, 2006 at 01:08
ThreadID: 34969 Views:12400 Replies:5 FollowUps:3
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I was talking to a friend the other day, who advised me that mining companies are mixing a small amount of oil in with a tank full of diesel, and are gaining something like 10% gain in fuel economy. Apparently the engines don't suffer, because of the lubricating effect the oil has (low sulpher fuels apparently have resulted in higher engine wear). Apparently truck drivers are also using the technique, and he says that a 630 km range from his tank has improved to about 750 kms.
He also mentioned that he knew of people who have put a small bottle of unleaded in with their fuel, which has given the motor a bit more grunt when squeezing the throttle pedal.
Has anybody heard of these practices or tried them out, and what was the result. My cruiser goes in for it's 200k birthday next week in preparation for an attack on the Gunbarrel and Connie Sue highways in about 3 weeks time, and I will certainly be asking my mechanic what he knows about the practice.
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Reply By: Member - Hughesy (SA) - Friday, Jun 16, 2006 at 06:21

Friday, Jun 16, 2006 at 06:21
The only reason that a mining company would be putting old engine oil in the fuel is to reduce fuel costs and be seen to be environmentaly friendly. When I was working for BHP years ago in the coal they were doing it. It doesn't give 10% better fuel economy. If anything economy goes down because old engine oil is less efficient than diesel.

If you own a diesel and you want more power than add a turbo. If you want better fuel economy than put a brick under the accelerator and stay in the left lane.
AnswerID: 178723

Follow Up By: Ray Bates - Friday, Jun 16, 2006 at 08:44

Friday, Jun 16, 2006 at 08:44
I worked for a mining company before retiring and the large diesel generators (5.5mw) had a centrifuge fitted that scubbed the engine oil as the engine ran. We rarely changed the engine oil and a sample was sent to the laboritory once a month for analisis and only when the oil lost its viscosity, according to the lab. was it changed but we never put the old oil in with the diesel
FollowupID: 434979

Reply By: Kiwi Kia - Friday, Jun 16, 2006 at 06:29

Friday, Jun 16, 2006 at 06:29
Several large truck manufacturers now use a system of slow but continous oil changeing while driving. A small amount of engine oil is bled from the engine sump into the fuel system and at the same time (and at the same rate) new engine oil is bled into the sump. The truck never needs an oil change, just change the filters and no waste oil to get rid of (just a bit more air polution).
AnswerID: 178724

Reply By: Member - Oldplodder (QLD) - Friday, Jun 16, 2006 at 08:01

Friday, Jun 16, 2006 at 08:01
Some trucks and earth moving machary do this.
Have heard of one civil contractor who has a feed from the sump into the diesel fuel line to the engine. The engine oil is topped up from an oil tank. This saves having to do oil changes on site, in which case it has to be done in a catch area etc., and the oil disposed off properly.
It really only works well once the engine is really warm, so the oil burns well with the diesel. It would be a smoky engine if there was a diesel/oil mixture in the tank on cold startup.

PS - Did look at this myself a while ago, thinking even if I could put 2 to 5 litres of old engine oil in ecery 150 litre tank, it would solve two problems, disposing of the sump oil after a change, and extend the fuel economy!
Decided not to do it on advice from a few on this site.
AnswerID: 178733

Reply By: Gerry - Friday, Jun 16, 2006 at 09:22

Friday, Jun 16, 2006 at 09:22
Accidentally put around 10% unleaded in my diesel tank once before waking up and realising what I was doing. Decided to leave it and see how it ran as I had heard of this practice before. Can't say that it made any noticeable difference while driving and still got around the same distance on a tankful. Haven't tried it since, but I would need a bit more convinvincing to do it on a regular basis.
AnswerID: 178749

Reply By: Brid from Cost Effective Maintenance - Friday, Jun 16, 2006 at 09:25

Friday, Jun 16, 2006 at 09:25
Using waste oil in diesel is not new. About 10 years ago, I built a unit to filter and meter waste engine oil into a diesel power station fuel supply for a mining operation. Slug dosing into a diesel tank causes problems, so it has to be metered and mixed. Proper filter selection is important. Cummins and Caterpillar, at the time of my research were happy to see a maximum of 5% oil in fuel. We calculated that our dose rate would be a maximum of 2%...a good safety margin!

Crankcase and hydraulic oil were regarded as fine, but definitely not transmission oil. I do not believe there are any efficiency benefits, apart from utilizing the waste oil. I often consider doing this on my own vehicle, but it's under warranty. If I still had my old Rangie with Isuzu diesel, I would do it in a flash, I reckon.

Using petrol in the diesel can provide more power, but it will shorten the life of your engine. Truckies who did this usually put it in the boss's truck, not theirs! (Otherwise they learnt the hard way.)

AnswerID: 178751

Follow Up By: TerraFirma - Friday, Jun 16, 2006 at 11:59

Friday, Jun 16, 2006 at 11:59
Hey Brid while I have you, what ratio of FTC Decarboniser should I use on Cummins Diesel Engines in my boat. I have a 750litre fuel tank. Should I use the FTC until it's gone in every tank or space out the mixing of FTC..?

I don't have any issues, just wanting to use as preventative maintenance..
FollowupID: 435030

Follow Up By: Brid from Cost Effective Maintenance - Friday, Jun 16, 2006 at 13:10

Friday, Jun 16, 2006 at 13:10
G'day Terra Firma

The treat ratio for FTC Decarbonizer is 1:800, so about 940mL of FTC for 800L diesel initially, then half that thereafter. It is designed to be used continuously to counter carbon & glaze effects, especially where engines don't work hard enough for long enough...seems to apply for most pleasure boats. Also serves to kill fuel growths..again pretty important for boats. That's when a lot of boat mishaps occur...bit of rough sea stirs up fuel tank bottoms, and plug filters, just when you need a bit of power.

All the best

FollowupID: 435042

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