Call me "over cautious" or call me "old fashioned" but it seems to me that if the manufacturers intended oil developed for diesel engines to be used in petrol engines it would say so on the label, given how strong our product labelling laws are in Australia. Perhaps this is being a bit simplistic but if an oil wasn't labelled "suitable for aviation use" would you put it in a plane? If you wanted to risk the engine cutting out at 30,000 feet and were a thrill seeker then maybe you would.
Having owned numerous bikes and cars since I started driving in 1968 (OK, I know, there were dinosaurs on the road it was that far back in history) I have always had an interest in the so-called "what oil is right for me" debate. Although the price of full synthetics is ridiculous (I wait until Super Heap have their 25% off sales to buy my Mobil 1) the use of varying grades and types of oil depends on what climate you live in, how hard you drive the car, what use the car is intended for, what the manufacturer recommends, what maintenance schedule you stick to (often forgotten), and what you can afford.
You also have to ask yourself if you have spent stacks of hard-earned cash and time on building or changing an engine, would you risk the project for some unquatifiable benefit such as possibly cleaning the engine out by using an oil not recommended or labelled for petrol engines.
I have used Mobil 1 Full Synthetic in all my vehicles for the past 15 years and never had a problem. However, recently in acquiring the SDub the mechanic I used in Sydney to get the car in condition to bring it back to Brisbane (it had been sitting and only run occasionally for 7 years) strongly recommended that I not use Mobil 1 straight away because it was too detergent for the older engine that may (or may not) have sludge deposits built up. Instead, a 15W-40 semi-synthetic oil was used and I have to say the start-up is much better, plus on the run back from Sydney the car returned 6.6l/100km.
Going back to the "dinosaur" comment I made I am sure that these posts will probably generate a lot of opinions as the oil debate always seems to, and there is nothing wrong with that. However, my mechanic who made the SDub recommendation for me backs his work with a 12 month warranty. If you choose to follow someone's advice because they are adamant that the solution works ask them to do the same.
Knightrous
fredhoon
Another interesting article dealing with oil in general, it has a short paragraph on using Diesel oil for engine cleaning.
http://www.carbibles.com/engineoil_bible.html
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.
Not much clarification on 'old petrol engines'... Is he talking old as in Ford 351 old or just a motor that's done 400000km. Wouldn't mind giving my 20V a good flush with some diesel oil since these motors can sludge up.