I, too, have a 1964 G2CSR. Just to add to the rest of the comments, I use SAE50 in engine, gearbox and chaincase. This means when I'm out and about, I only need to carry one type of oil to deal with the leaks. The good news is that, following work to various locations on the machine, the size of the bottle I need has gone down.
Now, about this blue smoke...............
Well, it's burning less than it used to leak so no panic yet.
Regarding detergent in the oil, don't panic unduly. Even Castrol classic GP50 of Morris lubricant as sold by the club (collection only) has some detergent in it, which holds fine particles of dirt in suspension and doesn't deposit them on the engine parts. Just look for a mineral oil with low detergent, avoiding anything with the words synthetic or semi-synthetic as this can cause clutch slip problems if you put it in your chaincase.
Several people here have read my exploits with Vesta, both when riding and when mending the poor little thing, some with amusement and some with concern that I really shouldn't be let loose with a motorcycle. One member's wife told me my bike is always broken. Not so! I have witnesses who have seen it out on the road just before I broke it again. I appear to be doing a complete restoration bit by bit, as and when I break something. A lot of this is a result of abuse and lack of maintenance by previous owners but, with the patience, tolerance and understanding of, mainly, club members, it's teaching me a lot about motorcycles. Despite the problems, which I hasten to add, are not compulsory for every lightweight owner, I love it to bits and, once you've got used to it, I'm sure you'll love yours too. Just don't expect it to perform the way your other bikes do. Being different is part of the charm.
Don't be afraid to ask questions, even those you may feel are silly, but I suggest you look through the various threads first because there isn't much that hasn't been talked about before. Your full membership status isn't showing on your profile and there will be some parts of the website that you won't be able to see until it is. If it doesn't change in a day or so, contact Eamonn, our webmaster, who will sort it for you. Unlike many of us oldies, he still has to work for a living and fit in a life outside the club, so it may take a few days. I also note that your live in Rushden. Our Jampot Rally next August will be at Rushden RFC so you won't have much excuse not to go. It's being hosted by the Heart of England Section. If you don't already know of them, they meet on 2nd and 4th Thursday of the month at The Lamb, 16-20 High Street, Stoke Goldington, Bucks. MK16 8NR.