CC004 POST-WAR OIL LEAKS/CHAINCASE

I wonder if you would advise on a couple of lubrication queries please:
1. The motor on my Venom was completely rebuilt about 700 miles ago so, knowing that the innards are clean, I'm using a 20/50 oil (Duckhams), assuming that this will be OK. But what gearbox oil should I be using?
2. Primary lubrication. I've done all I can to make the primary oil-tight but there are the inevitable leaks from the felt ring and, I suspect the rear of the primary case where it abuts the cork gasket. Nothing serious in terms of the volume of oil being lost - just messy!
Since I am unlikely to cover more than 2,000 miles a year on the Venom ( I use it in rotation with a couple of other bikes), it has been suggested to me that I drain the primary and instead lubricate the chain periodically, using a modern aerosol chain lube introduced via the inspection cap, perhaps augmenting this a couple of times a year with a fill to the primary for a few miles to lubricate the clutch. A colleague who suggested this pointed out that the primary case will inevitably get some oil mist lubrication by way of the small amount of oil entering from the crankshaft sprocket area. I would appreciate your opinion on the advisability of this suggestion - Roger Hinton 11/5/2002

I think you can use the same 20/50 oil in the gearbox, it might well be better than a straight 40 grade.
I agree with the comments about there being a slight oil mist into the primary chaincase, though on some (lucky!) engines it is almost nil. On these, I think the best it will do is keep the chain from rusting. It isn't going to penetrate the rollers which is where the lubricant is required. The primary chain has a fairly tough time for a single row chain - runs fast and gets hot, though it is at least out of the dirt. Having said that, if you are good at using a quality lube thoroughly and every few hundred miles, I think that would be OK.
The clutch can be run dry, and though the Velo manual says it will then slip if ever run in oil again, I haven't found this to be the case personally. (I think the club's plates would be OK, cork ones may not be so good). I think my main worry on running dry is for the operating mechanism of the clutch - the release bearing, etc. When I dismantled dry clutches after a season's racing they do look very dry and a bit 'tortured'. Packing the thrust and chainwheel bearings with grease gave them an easier time.
However, unless you are going to do thousands of miles at motorway speeds I think your plan is fine - lots of people run their Velos without oil in the primary chaincase, because it all leaks out and they don't check it!
I'm afraid you'll probably still have some oil mess - either because you have a lot or mist from the breather or through the sleeve gear bush and/or bearing; most Venoms suffer at least one of these. - TW 12/5/2002