Oil again sorry.

[marvic]

Hello all I’m new to the British bikes so I just have a question regarding oil. I have 1959 bsa a10 and was going to do an oil change because I just purchased the bike 6 months ago and haven’t reddin the bike yet. I was going to use silkolene Classic oil 20w50 oil for the engine and Morris  80-90 EP for the gearbox. Not sure about the primary but someone told me to use sae20. Please any help would be appriciated thanks 🙂

[Greybeard]

I use a straight 40 oil in my engine. I have an external oil filter.

I normally have Automatic Transmission Fluid in the primary but I recently had the primary case open and found I had no ATF to put in there so used the 40 grade. Not much is required, just enough to wet the chain.

I use EP90 in the gearbox.

Other people will have their own thoughts on oil.

The important thing about oil is that it can flow properly through the engine, so crankshaft sludge-trap needs to be clear and the timing side plain bush needs to be a reasonably good fit to the crankshaft so oil pressure is not lost at that point. If you need any further information on these issues use the forum search function, and/or YouTube.

[Black Sheep]

Silkolene Classic 20w-50 is a good choice for the engine as is the Morris 80-90 EP for the gearbox. I use similar oils for my A7 and A10. I keep the SAE 40 engine oils for my singles with roller bearing big ends.

[muskrat]

G'day marvic.
As GB said a search on "which oil" returned 42 pages of replies.
With an in line filter most use 20/50 or without a filter straight 30,40 or 50 (depending on conditions (weather or motor build)) in the motor. 80/90 gear oil in the box and either ATF or straight 30,40 or 50 in the primary.
All motorcycle specific oils are safe in the primary as their designed for wet clutch's. Don't use a car oil in there as clutch slip will occur.
Cheers

[RichardL]

Silkolene website sparse on specifications. I use Mobil VR-1 20W-50 racing oil for it's high levels of zinc (ZDDP). Good for the flat tapperts. Not street legal in the US, but anyone ever had their oil chemistry tested by the police?

Richard L.