HELLO FOLKS, PETE HERE. JUST WONDERING IF I COULD ASK FOLKS OUT THERE, WHICH TYPE/GRADE OIL SHOULD I USE FOR WM20 GEARBOX AND CHAINCASE. THANKS VERY MUCH.

email (option): petethejeep@hotmail.co.uk

I use Morris's straight 50 and 40 in the engine. Ron

email (option): ronpier@talk21.com

Many thanks for the gen Ron,kind regards, PETE.

email (option): petethejeep@hotmail.co.uk

And the same for the gearbox and primary...Ian

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

Sorry Ian, do you mean you use Straight 40 for all 3 applications, after Ron saying 40/engine and 50/ gearbox-chaincase

email (option): petethejeep@hotmail.co.uk

According to previous posts on this subject I think every oil known to man is, or has been, used at one time or another and everyone has a view on the subject...

Personally I think sae50 is a little heavy for the engine in winter/colder conditions...

I run sae 40 in the engine, gearbox and primary most of the time, changing to 50 for the engine and gearbox if we have a hot spell in the summer...

That's worked for me over 45 years of BSA single ownership...Ian

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

And my standard reply is even Woolworths oil today is a better product than what was available when they were being used durinf WWII.
Too thinand the engine will be noisy & leak like a seive
Too thich and you will loose some of the power you never had in the first place.

Monogrades, multigrades not much difference.

What is critical is how long it is in there.
Change it as often as you can and as none of us like to waste money, it is a lot easier to change cheap oil every month in riding season than $ 30 / l fully synthetic, which won't make one iota of a difference.

If the bike is new to you I advice to pick 3 different coloured oils for the engine, gearbox and primary.
It makes leaks easier to identify.

email (option): bsansw1@tpg.com.au

As Ian has suggested, these oil issues have been debated long and tedious over the years.

The manuals will usually tell you for the engine 30 in winter and 50 in hot summer. But as I'm one of those owners who doesn't ride on a daily basis, it would be difficult for me to adhere religiously to this. I could be changing my oil every time I went out

So I compromise with 40 engine oil in all my bikes all year round. And mostly 50 (or semi fluid grease in some) in the gearboxes. That way I don't have to keep stocks of too many different grades or remember what's in each bike. I always buy my oil from one of the guys selling Morris's at the jumbles for around £14-£15 per 5 litres.

As has been stated, any oil will do, but probably not a good idea to use a modern detergent oil in an old well used engine, or EP oils in the gearbox. Ron

email (option): ronpier@talk21.com

Agree with everything said.

EP gearbox oils are supposed to attack any bronze bushings (de-zincification)- though i've never seen any damage from using the stuff (by mistake).

P oils used to have a sulphur compound as the pressure carrying agent.
Sulphur chemically reacts with the high zinc phases of both brass & bronze.
Oddly enough it was added to ealy bonzes to make thm machine better, but that is another story.

It was very good in crash boxes but then along came the synctomesh box with nice brass syncro cones so they had to make new formulas for deluzxe cars with these new fang dangle boxes.Suitable oils were labled "SYNCRO SAFE"
By the time us paupers could afford a syncro boxes they were in every domestic ehicle and most light trucks so the heavy sulphur oils were relaged to the domain of truck oils

email (option): bsansw1@tpg.com.au

T - exactly .......

Must admit that since racing ##***'s and things - i have become rather cavalier with gearbox oils and use whatever i put in the engines.

Whether it says in the gearbox is another story!

I've never been a fan of grease in gearbox's though many g/box are 'designed' for the stuff.
I have used semi-fluid (steering box) grease with some success.

In the end, M20/21 and 16H's are basically low stressed lawn-mower engines - though (unlike mine?) i do think regular oils changes should be made - to stop internal corrosion as much as anything.