The 10/2 and 12/2 engines are basically two single barrels and heads on a bigger crankcase and with a 180 degree crankshaft. I have a complete engine in pieces if anyone needs any info on what is inside. The camshaft runs full width across the block and is gear driven the same as the singles with the same lube point at the non-driven end under the hex head plug 'Oil Daily' or whatever.
There is a centre crankshaft bearing with split shells, a plunger pump running off the camshaft at the front of the engine which feeds oil through 5 copper pipes into the bearings etc. Big-ends are scoop/splash lubricated.
Most of the injection parts are common, and the blocks, rods, pistons and heads are the same as the single cylinder engines of the same power. Note that the 3/1 engines are totally different from the crankcase upwards, very few parts are common but the bottom end is pure 5/1 or 6/1.
Oil has to be a Detergent type for any diesel, I don't know where this non-detergent oil idea comes from, but you'll soon have problems if you don't use the correct stuff. This goes back years, almost to the 1930's and it hasn't changed since!
Read any of the genuine Lister handbooks, they will always quote detergent oil. Synthetic oils are not required, and even thick oils are not always necessary, but detergent it has to be.
If you need information on 'why', look up one of the oil company technical sites which will tell you about holding dirt in suspension rather than allowing it to form deposits around the engine etc etc
Contact me if you need any further info on te twin cylinder (10/2 12/2) Listers, I can always pop out and take some pictures of the parts if need be.
Listerdiesel