Just a wee tip from a mate. When you change the oil, don't change the filter at the same time. The new oil has additives to clean the engine so take a wee run round the block till the engine is fully up to temp plus 10 kilometers or so and all the crud will go into the old filter. Then go home

then change the filter. Same if you are doing a flush but for the price of a filter I would put in a new one, do the flush and then put in another new filter.
As for diesels, My bulldozer ( John Deere 350 ) had a hole in the lift pump diaphragm and filled up its engine with diesel. Lots of diesel. I drained it, fitted new diaphragm and changed the oil and filter. What a difference. Easier starting more power and even after several days work when I dipped the engine the oil was still transparent.
I'm not recommending any one to do this/put diesel in their sump/ certainly not a petrol engine. It just makes me wonder what's in " Engine Flush".
So I personally put a litre of diesel in the oil filler the day before I do an oil change on the tractors and do the oil and filter at the same time.
Note:- Diesel has a detergent in it.
If you need something done quickly just ask a busy woman then get the f"k out of her way.