BSA Owners' Club Forum

The BSA Workshop => Twins => Topic started by: Fereday on 22 July, 2017, 19:33:34

Title: Oil
Post by: Fereday on 22 July, 2017, 19:33:34
Hi everyone at the moment I'm running my 1965 thunderbolt on straight 40 o!l would this be the best or is there an alternative.
Title: Re: Oil
Post by: TTJOHN on 22 July, 2017, 19:41:05
No problem with that during this weather but you may want to change to something like 20/40 as it gets colder.

Regards TTJohn
Title: Re: Oil
Post by: Fereday on 22 July, 2017, 20:01:47
Thanks ttjohn
Title: Re: Oil
Post by: Bess on 22 July, 2017, 21:39:40
Hi Fereday,
                 If you are going to use a 20/40 and it has detergent properties it will release and carry the sludge deposits. It would be prudent to fit a filter, change the oil and filter after 250 miles again at 500 miles before returning to the normal change intervals.

Best wishes...
Title: Re: Oil
Post by: JulianS on 23 July, 2017, 10:19:28
My personal choice for my A10 is Morris Golden Film 20-50 low detergent multigrade.

The mongrade you are using will probably contain detergents/disperents unless you are using something like Silkolene Osmaston or Donnington which are claimed to contain none are are designed for much earlier bikes than your A65.

I would suggest a good 20-50 designed for classic engines with low detergent, the Morris above being one and Castrol Classic XL 20-50 being examples of what is on the market.
Title: Re: Oil
Post by: Bess on 23 July, 2017, 15:01:53
Hi Fereday,
                 Be a bit careful with Miller oils, they have a statement in their product literature:

"CLASSIC 20w50 Mineral. Classic multigrade mineral oils were introduced in the early 1960s and solved the problem of using a different grade in summer versus winter. NOTE: Multigrade oils are not recommended for engines which employ roller-bearing crankshafts"

Best wishes...
Title: Re: Oil
Post by: Greybeard on 30 July, 2017, 21:16:33
Hello, folks.
My first post here despite having run BSA's since the 70s when I passed my test on my D7 De Luxe Bantam  ;) - currently I have a 1953 B31 and a 1952 A10 Golden Flash (both plungers) on the fleet.
I thought this article would be of interest, particularly the reference to detergency. Seems we could be worrying needlessly.


PS My membership form for the BSAOC went in the post yesterday.

Title: Re: Oil
Post by: Bess on 31 July, 2017, 12:54:38
Hi Greybeard,
                    Welcome to the forum.

I've read the techfile link with interest many times and cannot decide what is correct.

Castrol classic engine oils:

Quote -In older engines where the carbon has built up over a number of years detergents can have a scouring effect, causing the carbon to flake off, blocking up oil galleries and spray jets. High levels of detergent can also "wash" traces of carbon from seals and gaskets, revealing oil leaks where the carbon itself is creating a seal.

BSA service sheet 81, attached, warns of changing from low to high detergent oils and offers a solution.

I also noted the file recommended multi grade oils and touched on polymer shear. Miller oils do not recommend multi grade oils in engines with roller bearing on the crank due to polymer shear and stacking in the rollers. This has been noted within other technical documents but generally ignored.

I would love to see a definitive document on oils for my bikes but haven't found one yet, I'm now completely confused and don't know what to use, generally waiting for an expert to enlighten me.

Best wishes...

Title: Re: Oil
Post by: Greybeard on 31 July, 2017, 14:12:23
Im playing it safe  ;) straight castrol GP50 in all the bikes with roller big ends and Duckhams Q in the Golden Flash and the Matchless G9. Unfortunately Im down to my last gallon can (ah, a proper, good old Imperial gallon in a tin can, remember those?  ::)  ) of DQ after a mate cleared his garage out years ago and I ended up with a few cans.
I dare say once it's finally gone then it'll have to be something in 20/50 from Morris Oils or even Halfords  :)
With regard to sludge etc. Ive split many engines over the years and never come across one that has been a runner that has worried me. If its a really neglected/dead one that going to be rebuilt, then it'll get a proper clean out anyway.

As for an expert, isn't an ex a has-been, and a spurt a drip under pressure?  :D   I know, it's an old one. I'll get my coat.

Thanks for the welcome. TTFN.