I've had a search through the tech pages/old posts re engine, gearbox & primary oil and would I be right in thinking it's the same staright 40w mineral oil for both? Would a splash of that go in the primary drive case for good measure?
Also, are there level bungs/markers for engine, 'box & primary?
Dare I say I'm used to sight glasses on Jap bikes that share engine & gearbox oil!

email (option): lee@twowheelstested.co.uk

Hi Lee. I use straight 40 in my engine, and 50 in my gearbox and clutch case. But I don't think there would be a problem to use 40 throughout.
The filler plug on the gearbox is also the level plug.
There is a level plug near the bottom of chaincase below the foot peg. Ron

email (option): ronpier@talk21.com

Thanks Ron, Much appreciated.

email (option): lee@twowheelstested.co.uk

Just make sure its non-detergent. Here in the USA its a hunt to find non-detergent oil. Had a couple quarts on the counter the other day and suddenly saw a small print "special detergent". I run 40 in everything but am about to change to something heavier in the gear and chain cases. Hope it leaks less

email (option): micran1234@yahoo.com

I run SAE 40 in everything..The only practical way to stop the gearbox leaking (as it has no seal) is to fit a rubber sealed main bearing. That is a job best left for when the gearbox needs some other repair work.
In the meantime you will have to live with some leakage and keep an eye on the oil level. Fill the box until the oil is visible in the filler neck of the box and check it about every 500 miles, topping up as required.
As Ron says you will see the level plug for the primary chaincase just below the footrest in the outer cover. Remove this and the large brass inspection plug at the top of the casing. Stand the bike on level ground and top up slowly until oil starts to dribble out of the level plug..Make sure you have a fibre washer fitted to the level plug before replacing it.
I usually fit an 'O' ring to the inspection plug.
For the engine, fill the oil tank until the level is about 1" below the top of the return pipe located inside the tank. If you remove the sprung loaded cap on top of the filter (if fitted) you will see the pipe inside the filter...Ian

email (option): ian@wright52.plus.com

I never thought about this, but after reading this thread i realise that most of you run SAE40. Would it be a problem to use SAE50 in the engine, this is what I'm used to after riding harleys for 20 years.

I think 50 is fine for these roller bearing engines Ynse. But it is a bit heavy in the cold season. It's recomended to use SAE 30 in the winter and SAE 50 in the summer. Since we don't live in the Artic or the tropics! I think 40 is a good all year compromise. Ron

email (option): ronpier@talk21.com

I'm definitely not the expert, but here in the states our regular store bought oil no longer includes ZDDP (zinc and phospherous) because it supposedly ruins cataletic converters. New car rollers and roller bearings don't need ZDDP, but all the info I've read indicates older bikes and cars with friction surfaces definitely need the oil with ZDDP.

I haven't seen that discussed before on this forum, but if traditional high levels of ZDDP is needed, in the US you have to go with synthetics unfortunately. Mobil 20-50 V-twin Motorcycle Oil and Amsoil Motorcycle 20-50 are best. I'd prefer not to use synthetic (search the forum for arguements either way), but i've searched high and low and have not found a straight grade in the US with ZDDP. By the way, this is for the engine only.

I was told with the multy grade oil to work they need two factors to change viscosity,Heat & Pressure with the roller bearings used in the engine the multy grade oil is not put under the pressure for the oil to change viscosity . That is why a mono grade oil is desirable
Michael

email (option): michael@nammech.com.au

i should think there are oil suppliers that still do oils for old an classic vehicles

I've been trying to source some WM20 oil and thought I'd cracked it with Silkolene Chatsworth but the brochure says detergent - not low detergent, just detergent. Is this sort of oil likely to free-up 67 years of deposits that'll then run riot around my motor or will it be ok?

email (option): lee@twowheelstested.co.uk

Google Morris's Lubricants...they do a suitable oil. It is also stocked by quite a few Brit bike shops if you have one in your area..Ian

email (option): ian@wright52.plus.com

I've just had a look at the Morris site - would their Golden Film be the one? 40 in the engine & 50 in the 'box? Ps, any news on the mag?

Hi Lee..Yes, Golden Film is the one...I'll mail you about the mag...Ian

email (option): ian@wright52.plus.com

Thanks Ian

talking about the level plug, could some kind soul tell me which is the level plug? Is it the very small plug at the bottom? Not the inspection plug obviously?

email (option): andrew.honychurch@btinternet.com

Hi Andrew..Yes, the level plug is the small one located in the face of the outer cover below the footrest. The drain plug is underneath, through the bottom of the inner cover...Ian

email (option): ian@wright52.plus.com

I always used 'Golden Film' when I was in the UK and found it satisfactory. The Classic range are low-detergent oils. I haven't heard of anyone using non-detergent straight oil for a long time.

Personally, I wouldn't want to run an old engine without first dismantling and cleaning.

thanks Ian, funnily enough there is very little mention of what the lubrication details are for the primary in any of the information I have. As far as Golden Film is concerned, this is made by a firm called Morris Oils and are from my home town of Shrewsbury. We have always used it and always will if I can find it. I just managed to find SAE 50 from them and was delighted.

email (option): andrew.honychurch@btinternet.com