Ive heard about people using diesel oil in their cars for a day or two before doing an oil change as they have a higher amount of detergent to help clean the engine out. Im about to do the oil and filter on my KH, has anyone ever tried the diesel oil to clean out the engine?

has diesel oil got the same properties as the engine oil we use (viscosity and temperature tollerance etc)? If so, then it may be able to be used.

Found this on carbible:

Using Diesel oil for flushing
A question came up some time ago about using diesel-rated oils to flush out petrol engines. The idea was that because of the higher detergent levels in diesel engine oil, it might be a good cleaner / flusher for a non-diesel engine. Well most of the diesel oil specification oils can be used in old petrol engines for cleaning, but you want to use a low specification oil to ensure that you do not over clean your engine and lose compression for example. Generally speaking, an SAE 15W/40 diesel engine oil for about 500 miles might do the trick.

I would strongly recommend you don't. You might read a thousand articles telling you to do so, but I've seen what it does first hand.

2000 Barina, 130,000kms - Diesel oil put in. 133,000kms it threw a rod through the block.

Was it still running on diesel oil for those 3000 kms? I thought more along the lines of 50km of driving with diesel oil of about 10/15w-40/50 then change the filter and put regular oil in. Someone at work used an additive that you do before an oil change but he said it started blowing heaps of smoke so he changed the oil again and it was fine.

dont drive with it in. Just idle. Also, as carbible states, don't do it excessively with an older engine otherwise loosened sludge may clog things and cause massive damage.

Was it still running on diesel oil for those 3000 kms? I thought more along the lines of 50km of driving with diesel oil of about 10/15w-40/50 then change the filter and put regular oil in. Someone at work used an additive that you do before an oil change but he said it started blowing heaps of smoke so he changed the oil again and it was fine.

Yes, the diesel oil was in there the whole 3,000kms. My old boss also tried it on 2 other cars we used, a 2000 Holden Commodore and a 2002 Nissan Pulsar - all the cars started making ticking noises soon after the oil was changed to diesel oil.

Unless it's a really old engine or it really needs to be done, I would avoid using diesel oil. If you must, just use an engine flush, but be careful as vlad mentioned.

solution: change your oil and filter with good quality oil on a regular basis, i do mine 5000kms oil is still very runny, and just turning black

Will skip the diesel oil and flush, since it looks like there is a fair bit of gunk in there and its probably best left attached to things rather than floating around in clumps.

Check out this website:

http://www.bobistheoilguy.com/cms/

lots of info there. Some engines sludge up no matter what you do. An engine flush just before an oil change helps.