Correct oil for 66 BSA Spitfire

[VintageBike]

Just got myself a Mk3 Spitfire and need to find out the correct oil spec.  I haven't got myself a manual yet and can't wait a secind longer....  Can anyone help?

Cheers

Nigel.

[L.A.B.]

If it's a MkIII then it should be a '67 *model year* bike?

Although of course it may have actually been built in late '66?
Does the engine/frame number have a MkIII 'A65SA' prefix? Mk II would have 'A65S' engine prefix and frame would be 'A50C'.

The oil recommendation stated in the owner's handbook at that time was still for 'Summer' and 'Winter' engine oil monogrades, or narrow band multigrade,  EP 90 for the gearbox, and SAE 20 grade fork oil.

The later engine oil recommendation for A50/65 was for 20w/50 multigrade.

[VintageBike]

Yes Les, it's matching A65SAXXXX.  It was despatched to BSA West Coast USA on 23/9/66.

So it's monorgrades then - I knew that later models were 20/50 and the earlier ones were monograde, but wasn't sure where this one sat.

Thanks.

Nigel.

[L.A.B.]

So it's monorgrades then - I knew that later models were 20/50 and the earlier ones were monograde, but wasn't sure where this one sat.

Well...No... the engine oil recommendation changed when multigrades became more widely available (and accepted) the A50/65 series engine's internal specification didn't change, therefore multigrade oil should be fine, and may well be what is in there now?

[L.A.B.]

Oh...I almost forgot, the primary chaincase recommendation was for SAE20 or 20w/30 oil as given in the '67 book, the later recommendation was 10w/30 engine oil, but ATF may be the preferred option for some owners.  

[henry_norton]

Just curious, but I always thought modern multigrades will always give your engine better lubrication and protection in comparison to 'old fashioned' monogrades. That's unless you run a Norton rotary or bevel drive Ducati of course. Is there really a difference 'on the street'? H_N