An oil question

[Bob Purton]

I need some sae20 oil for my villiers chaincase, I have W20 fork oil, is this the same? Forgive my ignorance but the numbers before oils have always been a mystery to me!

[Barry]

The answer may be here - have a good nights sleep................

http://www.upmpg.com/tech_articles/motoroil_viscosity/

[richard]

Well this was a right old can of worms last time we went there . I searched primary from richard to set me off - and it has , nite nite

[Big Al]

Fork oil is designed to dampen, therefore to flow. Engine oil rather more to stick as a film. I think Fork oil is referenced in weight of the pressure on the forks rather than viscosity, which obviously is a measure a product of a known weights speed of movement in oil, very similar but recognizing the differing property. In other words the same density oil would see the Fork oil move faster as it is not as sticky. If that is a correct assumption then while Fork oil will work it will not stick onto the chain in the way SAE20 would. On balance I would suggest SAE 30, more readily available and possibly in stock in the Purton or local mates garage, might be better than Fork Oil W20. Cannot see it would do any harm to try the Fork Oil. Certainly would not do it the other way round but that is a whole different question.

[Mark Green]

I had a hard time finding sae20 oil for our villers chaincase. I finally found a case on Amazon.com so I am set for a long time. I just checked and Amazon UK has some listed. I was told not to use any synthetic oils  just straight sae20. Good Luck

[Bob Purton]

Thanks chaps. Like Al I was under the impression that the W had something to do with weight but that chart from amsoil talking about W for Winter only adds to the confusion. As this chain case oil  also wets the clutch I had better buy some of the recommended stuff and keep the W20 fork oil for the Motobi.. I wonder why different manufacturers come up with such diverse oil spec, the Sachs is the same size with a wet clutch and specifies a straight 90 gear oil. I guess its a compromise, treacle to hold the weak gearbox together    With the villiers it has the luxury of a separate chamber for the clutch and primary chain so a more suitable oil is specified and is different to the one used in the gearbox. I only hope the oil stays in there after this rebuild, I still have fears of it all running out of the speedo drive unit at the lowest point of the engine which has no oil seal in.

[Big Al]

Put an oil seal/fibre washer in the end of the speedo cable. The oil goes up the speedo cable but as long as the actual instrument is a good distance above the Archimedes effect on the oil, should the speedo cable turn the wrong way, it should still keep it dry. Advantage, well lubed speedo cable.

[Bob Purton]

The foresight of that man Archimededs is phenomenal! Who would have imagined he had villiers speedo cables in mind when he invented that screw!

[Jim]

http://www.holden.co.uk/displayProduct.asp?pcode=090.967

[DaveMiller]

Or £6.25 at Villiers Services:   http://villiersservices.co.uk/index.php?main_page=product_info&cPath=47_48&products_id=40

(Steve has mistyped "straight 30" when he meant "20")