Opinions on Engine Oils.

[Triton Thrasher]

The gunge is hardly likely to be released in one big lump

If anything was to come out, maybe sizeable bits would come off and block oilways.

But I doubt that anything short of caustic soda would move the stuff in the sludge trap.

[69Bonni]

I guess your all correct!
I changed to a detergant oil in a '68 5TA i used to have, and there was a marked increase in the amount of sludge build up every time i changed the oil. Which concerned me so much it was a factor in deciding to rebuild the engine, inside the cases it looked decidedly cleaner, now whether that was me trying to look for something i dont know, the Sludge trap wasnt that bunged up either 1/2 full, maybe it had been cleaned before?
I have no doubt about the cleaning effect of detergent oils, like Josh says. I can also remember when Duckams brought out there "Green" (green as in colour) 20/50 this was much malighened and slated at the time for being heavily detergent and at the time was reputed to not do "Old Engines" any good, this was supported by my father and father inlaw both old school motor engineers. Who by the way told me if a cylinder head isnt hardened enough after 40years putting in "Hardened valve seats" for unleaded petrol was a load of Bl***ks.

I think if you intend to run on a detergent oil if your bike isnt a later (Late 60's) bike, then probably change over after an engine rebuild, and certianly fit a after market oil filter.

For longevity its gotta be regular oil changes and an oil filter every time! Im not convinced carbon will destroy bearings maybe the particals of metal floating around in the oil might!

What want good when i was 19 i put Holts de coker into my B44 and it did a fantastic job of removing any compression that remained! an excellent cleaner! Perhaps i should
have decoked it properly, i wont tell you what my Father said after looking at the shed wall!!

As for Shoddy engineering!! wernt they all!! we all know bikes were built on assembly lines .... End of! and it doesnt take much to put them together right! i dont think they would have time to mate the surfaces as we have time to. I love my BSA's, but we all have short memories! most of my bikes were held together with checker tape (go faster) jubilee clips and fence wire, and what ever engine wasnt blown up! Matching numbers .... A miracle!

IKBA and Bar

Regards
Steve

[BSA_54A10]

It will help a lot if you all forget the term "SLUDGE TRAP" and think of it as what it actually is "FULL FLOW CENTRIFUGIAL OIL FILTER".
If you can do this then it will all become far more clear.
What is in the crank has been put there by centrifical force, not the oil. it will continue to work regardless of what oil is in the engine and will work exactly the same regardless of what oil is in the system because it seperates out the particulate matter according to variations in BULK PHYSICAL propereties and in this case the density by means of differential kinetic energy. And if you think about it, the lighter & thinner the oil the better this will work.

Now for the fun one, DETERGENTS IN OIL.
I rarely cite things in posts because I firmly believe that no one should take any thing that they read on the web as undeniable truth until they can independantly verify it. However in this case I shall I shall quote chaper and verse.
Book ;- Lubricants, Cutting Fluids and Coolants by W J Olds
ISBN 0-8436-0812-9
Publisher Cahners Publishing Company 1973.
Chapter 17 ;- MYTHS ABOUT MOTOR OILS
Detergents and Dispersants

"Many name brand motor oils are clearly labeled  DETERGENT. And just about every lubrication engineer that gets into the subject claims that this is an inaccurate description because the detergent oils do not clean up existing residues of carbon, sludge, etc . On the other hand, Webster's dictionary defines a detergent as an oil-soluble substance that holds dirt particles in suspension - which is exactly what a detergent motor oil dose."


So here is the drum.
The detergent molecules float about in the oil and when they bump into some thing that is not oil they surround and encapsulate it. In doing this they give the particle a charge ( negative I think) . The dispersants see these charged globs and further encapsulate them but the dispersants can not join onto themselves so they keep the crud as a separate tiny glob so that the cartridge filter can trap them.
A lot of very cleaver chemical engineering goes into controlling the actual size of these globs, way beyond my knowledge of bulk organic physics.

Now Diesel engine oils are different again.
They have additives specifically designed to bond onto carbon and they will do this regardless of weather the carbon is free floating in the oil or deposited on the engine. The ability of these additives to actually remove the deposited carbon is dependent upon which has the stronger bonding .
These ADDITIVES are not found in general motor oils but do get put into special race formulations.

Advertisement copy writers are not particularly well educated and this is particularly true in the engineering fields. However that are very perseptive on what sort of BULL SHIT the public will believe without question thus the popular myths about detergent motor oils.  

[69Bonni]

Cracking stuff Trevor,

A lot of myths about these things isnt there!

So if these oils are used then its important to use a filter!? So this poses another question on filters, the detergent picks up the crud and drages it around with the oil to be deposited in the filter, so are these crude mesh filters efficient enough to encapsulate the crud carried by the oil?

So the better the filter the cleaner the oil and the less everything else gets bunged up. Cartridge filter time.

So would that mean that the "FULL FLOW CENTRIFUGIAL OIL FILTER" would tend to get less clogged? I assume with a more efficient cartridge filter this would remove best part of the suspended particles.

Do you thing running the engine on for example 20/50 with a cartridge filter is the way to go? Which is probably the Nub of the question

Kind Regards

Steve

[BSA_54A10]

Yes.
These pages are full of posts where riders have fitted a cartridge filter and found that after many years there is almost nothing in the tube in the crank.
OTOH if the filter used has a bypass and lets unfiltered oil around the engine then the original system will kick in, sort of belt and braces approach.

I am sure that I (for one) have posted the full thesis on BSA oil filtering system.
Each of the filters is there to protect the component directly downstream of it thus the mesh in the sump is coarser than the mesh in the oil tank and neither of these will remove "encapsulated crud" that is the job of the "full flow centrifugal oil filter" which by the way is a dead end tube so there is no way that anything in there will end up circulating in your engine. The problem comes when stuff that should end up there starts to circulate because it is full or even worse when it gets over full and blocks off the oil way.
When our bikes were made, oils were very crude by todays standards and BSA designed the lubricating system to use these oils.
Part of the system was to allow the oil to form a sludge in the bottom of the oil tank. To do this the oil must not have dispersants present and by prefference not much in the way of detergents either .
Up until recient times most mono grade oils did not have dispersants in them which facilitated sludging out in the oil tank ( I used to believe that they had flocculants in there, but I was wrong). However a recient poster to one of the forums that I haunt mentioned that just about every monograde oil now has detergents and dispersants in them and when I checked he was fairly well correct .
Armed with this new information I no longer recommend useing monogrades in original systems and multigrades in externally filtered systems as there is very little difference in them and special "vintage" oils are now very expensive and observing the reluctance of British bike riders to spend money , seriously doubt that they would pay 3 to 5 times the service station price for oil that fitted the outdated specifications of BSA in 1959.

Far more important is to hammer home the "change the bloody stuff " philosophy than the "use the right stuff " philosophy. Oddly enough there have been hundreds of posts regarding "which" but none regarding "when" and the latter is 500 times more important than the former . 

My oil usually gets changed about every 6 months when I am not using the bike very much and monthly when I was actively using the BSA . The van got an oil change every month so the BSA got done at the same time.

I do hope that I have not offended any one but this is a myth that needs to be busted. Detergency is a complicated subject and it was hard enough for a class of bright uni students to get their heads around back in the 60's before TV had implanted so much miss information into out brains.
The book by the way was a text from a post grad course at TAFE , not designed to make us all lubrication engineers but to give us enough background to tell is the sales rep was spinning us a line. 

[69Bonni]

Thanks for that Trevor!

Brillent stuff, and interesting reading, all these years and you still learn something new! its nice to have someone confirm what i'd always thought.
I know the forums have been full over the years of "Lubrication" discussions and its great to hear at least that what i have always thought and preached to others is correct! (Thats a weight off my mind). Its interesting to hear that even the Monogrades have detergents now guess its not suprising.
I bet everyone here has shoveled out heaps of gunge from the oiltanks when rebuilding which nowadays with good oil frequent changes and effective filters it shouldnt happen.

The good news is you do what i have always done regular oil changes, after all its the life blood of the engine! Spending out on oil is a lot cheaper than finding a new set of crankcases!!
Thinking about it further, if someone has an engine that they havnt split down, its probably safer, assuming they are not intending to in the near future, to run the bike on something like 20/50 and fit a filter less likely that the centrifugal oil filter blocks and kills an oil way!

I think you have done a first class job on busting the myth Trevor, and im sure everyone will benefit from it. (hope you havent repeated this to many times!)

Thanks Trevor

Kind Regards
Steve Rickman

[bsa-bill]

I Read somewhere that the( (green) Duchams 20/50 was infact designed with Motorcycle engines in mind (air cooled).
Might be more urban myth of course/

All the best - Bill

[Triton Thrasher]

Trevor and many others know more stuff than me, but I think a good centrifugal filter can remove carbon particles small enough to pass through a paper element. If sludge traps are staying clean when a filter is used, then maybe old bike sludge traps don't actually collect that carbon.

[bsaalf]

i use standard 40 wieght in the summer and always change it often ?

[BSA_54A10]

Like paper filters that come is different mesh grades so mechanical filters are designed to have different filtering characteristics and can be made to filter out particles so fine a paper filter can not remove them but this is not the case in our engines .
In the case of our cranks the crank filter will pull out all gram positive particles that are bigger than the gap between the bush and crank and/or the pin and slipper .
These smaller particles and the gram negative should drop into the cases then get pumped into the oil tank where the heavy bits should drop to the bottom and the light bits should float in the foam on the top.

Now for the crunch the dispersants in modern oils hold these fine particles in suspension stopping them from dropping out to the bottom of the oil tank and keeping them in circulation. All this sounds horrific but the quality of modern oils is 2000 times better than the oils of old.
The only thing that I avoid is light oils 5W anything , 10W anything or 15W anything. These oils are designed to drain clean off the engine thus providing less drag when cold allowing CAR engines to start easier . And if you think that this is insignificant try kicking your engine with a sump full of oil.
Heavier grades of oil 20W anything, 25W anything and higher do not usually have the addative package to drain clean as they get used in older engines with bigger clearences where the cold viscious drag is not so significant. The same applies to monogrades so I suppose that would be a good reason to use monos.
In Oz a local company Penrite do a range of oils HPR that are formulated not to drain off and I used to use these oils but now days they are nearly twice the price of the Valvoline 20W50 that I use and that makes them a bit too dear ( so I do not keep enough on hand and thus don't change the oil often enough )  
One thing that the TV commercials got right is the "Most engine damage is done during start up" line.
So more important than which oil you use is your starting routine. Blipping the throttle or reving the cold engine hard to "warm it up quickly" is probably the most dangerous thing that you can do to your engine and this gets more important with bikes that get used occasionally. A dozen or so kicks with no ignition to get some oil circulating before the bike starts is a good idea , a bit of a PIA to do with the twins but easy with the bigger singles fitted with decompressors.
This is what killed off the Ducatti 750's Desmo , desmo head, no valve resistance, heavy oil , 0 to 10,000 rpm in an instant on a stone cold motor way before the oil had built up on the bottom end = sliding metal to metal contact on the rollers. Ask any owner how long they got out of a bottom end.


So now every one is totally confused what is the wash up ?

The original system as BSA made it is more than good enough, provided you change the oil very regularly.
External oil filters will make it even better provided that you don't use the filter as an excuse for not changing the oil.
The sludge trap should be cleaned out every 100,000 mile if you change the oil very regularly and /or have a filter fitted or at  50,000 mile if you don't which should be about the same time as a set of new rings.
Oil tank should be removed and cleaned out at the same intervals.
Prime engines that have not been used for a long while .
Once started allow the engine to rev slowly to warm up and build up a full oil film.
Type of oil ? heavier is better than lighter, classic limited use blends are better still but not if the cost makes you afraid to change it.

[Brian]

Good stuff Trevor, like you I changed from Penrite to Valvoline due to the cost. Over here the Penrite is twice the cost of the Valvoline. As you have stated the most important thing is regular oil changes, I always say oil is cheaper than engines.

The one thing I would like to take you to task on however is your statement that the sludge trap is actually a full flow centrifigal oil filter. Full flow by all means but I dont think they can be considered a centrifigul filter. If the sludge trap was in the centre of the crank it would be a centrifigul device but as its in the journals the oil would throw to the outside which also happens to be the direction of the oil flow. No doubt some particals would adhere to the inside of the tube but on the outer side I would think. Theres no doubt that the sludge trap collects lots of stuff as  sometimes they are caked solid, I've had one I had to destroy the tube to get it out. However as modern oils keep most of the particals in suspension I wonder if the tube in the sludge trap is doing much. Changing the oil while hot and all the rubbish is in suspension would seem to be the most effective way of keeping the engine clean on the inside and consequently wearing less.

Briefly going back to centrifigul filters for a minute, they were used very successfully by Honda in their small capacity engines in the seventies. They were always full when you dismantled them to clean them out.

Just a few thoughts, what do you think.

[LJ.]

Theres no doubt that the sludge trap collects lots of stuff as  sometimes they are caked solid, I've had one I had to destroy the tube to get it out.

I wonder if a 'caked hard' sludge trap happens because of thinner oils used, particles may travel faster through a thinner oil than a thicker oil and then compaction in the sludge trap happens easily... just a thought.

[BSA_54A10]

OK pedant, I'll fix you, bare knuckles, back of the admin block @ Torquay in October.
It is not as much of a centrifugal filter on a twin as it is on the singles but it is still a cetrifugal filter as the oil is being pumped in one direction while the crud is being thrown in another, but I do conceede your point it would not be the strongest one ever made.

[RichardL]

Au contraire! (Just throwing in for fun here.) The sludge trap through the rod journal should be the far beter centrifugal filter than one through the center of the crank, considering the rotational velocity while completing one revolution versus that of the center of the crank. More velocity = more force.

Richard L.
 

[Brian]

This is a bit off track but I just had a thought (no it didnt give me a headache!) Considering the quantity of oil that is in the crank, somewhere around 20 to 30ml, and the fact that the oil is offset of the centre, I wonder if anyone takes the weight of the oil into account when working out the balance factor of a engine. Just a thought.