Author Topic: Zinc content in oil  (Read 7778 times)

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Re: Zinc content in oil
« Reply #15 on: June 19, 2017, 10:55:44 PM »
I feel like that as well, have to think about one part of it at a time else brain goes to overload  :)

It's partly right in that if you keep the oil in good condition you are less likely to break through its structure. But that is balanced by some engines having a camshaft loading so high that the oil, even in new condition,  will only just about survive the loading it takes.

Fortunately the SOHC fours have well designed and considered valve gear geometry on the whole which will mainly not give problems, but, it's easy to make any engine step over that limit. One way is to have valve clearance too small,  this does not allow the oil film to re-establish on each rotation of the cam so the depleted oil supply as the follower comes up on the ramp it breaks through the oil and gets metal to metal contact.
Another easy way is to keep running the bike alot on choke with no long journeys. The oil is quickly diluted with part burnt petrol and other contaminants from rich combustion, this very quickly trashes the oils shear properties and offers low protection to the cam.

Offline Bryanj

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Re: Zinc content in oil
« Reply #16 on: June 20, 2017, 06:07:24 AM »
Don't forget when we use the oil it is getting hammered as gear oil as well

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Re: Zinc content in oil
« Reply #17 on: June 20, 2017, 08:09:31 PM »
At first appearances it looks like that just because the gearbox looks so gnarly, it gives the impression it would badly affect the oil. But different gearboxes are designed to run on different types of oil which if done correctly will not adversely cause any real harm to the oil.
Most gearboxes with their own oil will run many thousands of miles without changing the oil,  it's the combustion by-products in mixed systems that prematurely degrade the oil with the risk opposite to how it's commonly perceived ie, dirty diluted oil puts the gearbox components at risk.

I've thought through about your point Mick,  about anti wear properties (talk about taking one thing at a time) the oil film is likely to be breached each time a motor is started. When it's turned off and left then the oil that was in the bearings partly leaks away,  then when you go to start it again you are reliant on the anti wear properties to prevent damage and metal pickup until the oil pump has pressurised all the bearings again. As soon as that crank starts rotating and the big end gets thumped by the compression it won't have the desired pressurised oil film to protect it. The cam is also under valve spring pressure / load right from the off, whether any oil is there or not.

Offline totty

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Re: Zinc content in oil
« Reply #18 on: June 21, 2017, 12:34:45 PM »
Isn't separate gearbox oil which is ran for high mileages normally single grade?
I'm sure I'd read somewhere that gearboxes break down some types of viscosity improves used in multygrade oils, causing the oil to get too thin at high temperatures.

There's another consideration but I'm not sure if it's just marketing hype, which is extreme pressure (EP) additives. Gearbox oil is typically marketed as EP oil, they used to market specialist EP oils for A Series engines due to them being one of the few cars with the gearbox sharing the engine oil, and it used to be one of the justifications for bike specific oils being required.

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Re: Zinc content in oil
« Reply #19 on: June 21, 2017, 08:16:37 PM »
Each gearbox would by designed from scratch to use a different type of oil, an ep oiled box and most differentials will take advantage of that level of protection by asking it to transmit a higher level of torque for a given component size and ratio change.
You're right that gearbox specific oils are often monograde or restricted viscosity range eg 75/90. But one of the main differences is that gearboxes mostly don't have a pumped system of distribution so that you don't run into cold oil hydraulic locking the pump as all the components cope with torque ratings far in excess of that needed to move sticky oil around. It'll just cause drag and power loss until warm.
Compare this to an engine,  they have to pump oil round to all components so by default need to run a pump. Most engine oil pumps if you started with mono / hot grade oil 40 for example will be at risk of hydraulic pressure overwhelming the oil pump drive if you started it in zero degrees, this is why before multigrade was available you'd have to tailor your oil viscosity to cope with seasonal temp variations.
The Mini combined system may have benefitted from a heavy duty or extreme pressure denoted oil as you say but I think this is nothing more than a zinc heavy bias to the additive package, like the original post title asks about.
There are other examples of boxes running engine oil. The original range rover 4speed was designed from scratch "lt95" to do this and incorporates a pump to lubricate it, you can't run something like ep90 in these for risk of shearing the oil pump drive.

The add package components in transmissions oils I don't think are in any way suitable for use in engines. They use things like sulphur, that although being resistant to some heat in normal use won't tolerate direct surface contact in places like cylinder heads as I understand it.

Something else component wise that look like it benefits from ZDDP are the internal chains, both cam and primary drive. The size of the bearing surfaces and torque going through the primary are candidates for bringing oil film on its own to the very limits of protection via  the pressure they're able to exercise.

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Re: Zinc content in oil
« Reply #20 on: June 26, 2017, 02:14:47 PM »
I wondered if anyone else would dig up some interesting stuff in this area, but thought I'd add some more.

Like you've done with the mini transmission Totty, I use different application to help me explore some of the limits of this subject, makes for interesting comparisons of why the original design and specs called for some particular oil or procedure.

Following is why ordinary transmission don't necessarily need a heavyweight EP oil of the type commonly used in differentials. Generally gear tooth design places the meshing teeth very carefully against each other as they come into contact, with very little sliding between the faces coming into contact. It's sliding metal to metal that causes the most stress to oils. Wether the gears are straight cut or helical makes no real difference as far as I can see, helical just being quieter than straight as it's less prone to set up a resonance pattern with each tooth taking up drive slowly rather that all at once.

The need for those transmission oils specifically labelled EP comes from Hypoid gear arrangement used most commonly in axle differentials. What that design does is to take the pinion centre and offset it from the crownwheel axis. This involves a tooth design that is hyperboloid being a cross between a worm drive and a plain pinion. It's this design that has a very high amount of sliding between the gear faces and as such requires the special adaptions within the oil to resist oil breakdown and total destruction of it's shear quality that would effectively wear the metal. The advantage of using a Hypoid design is that the pinion can be much larger than a straight on axis design but without increasing the crownwheel diameter, this keeps the diff compact while allowing a high torque capacity in as small a space as possible.

Notably, the old Mini transmission, I think, drives from it's final drive onto the differential cage without any Hypoid gears, it's this aspect that makes it a technical oddity and doesn't require special oils of the degree discussed above.

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Re: Zinc content in oil
« Reply #21 on: June 26, 2017, 02:52:57 PM »
Really appreciate reading all this stuff K2-K6 . Just was this section was created for. Like 'Jensen' who I mentioned,  you may not get a flurry of responses as the info takes a bit of absorbing, understanding and reading around. But it's here as a great reference and easily accessible outside of the 'day-day' forum posts.

In the early 70's I had a Honda CD175A sloper. The local Honda dealer 'Ken Blakey' who had been a dealer since early doors waxed on about using 'Filtrate' oil in Honda's (dark grey because it has molybdenum disulphide in it). So, at great expense, I replaced the 175 oil with Filtrate oil  but at the next oil change I cleaned the centrifugal filter housing and was shocked to find so much black stuff in the housing that there was only a pencil size hole down the centre.  So what was all that about? Does anyone else have experiences with Filtrate oil (it came from Leeds)?
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Re: Zinc content in oil
« Reply #22 on: June 26, 2017, 04:06:58 PM »
Some mention of it here . Perhaps it was colloidal graphite not moly.

http://www.voc.uk.com/net/docs/4.2/4.2-437-20.pdf
“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

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Re: Zinc content in oil
« Reply #23 on: June 26, 2017, 04:16:33 PM »
As Totty says, they are very different as I understand it.

Our modern use of graphite is most commonly found is Graphogen used as an assembly lubrication particularly for cam lobes and followers, but as you found not applicable to general oil use for our bikes on this forum.

I've some interesting back stories of filtrate etc which I'll post next, just got go out and collect my daughter from school right now.

Nigel.

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Re: Zinc content in oil
« Reply #24 on: June 26, 2017, 06:45:43 PM »
Apologies Ash, I got my poster's mixed up there.

I understand it as that voc letter places it,  the oils of that time when it was mostly in use were non detergent type so you expected the contaminants and particals from use to drop to the bottom of the sump to be drained out at change time. I'm not that knowledgeable about pre sixties oil filtration systems but ones I've seen have been fairly rudimentary in a basic gause type that would just stop any chunky bits going round again and leaving the graphite in its colloidal distribution to go round undesturbed.

For those looking information,  this may help to place what they mean by colloidal.

http://www.whatiscolloidal.com/colloidal-definition/

I guess the Filtrate name effectively refers to a whole package that fits with the engineering of the time in working with contaminate dropout and preserving the additive it would do what they claimed. But as you found with a centrifuge oil filter (likely to be paper filter type as well)  the engineering design effectively obsoleted their method. Curiously, a centrifuge filter could possibly out perform a paper type with a solution like that.

Interestingly, most car CV joints use that type of lubricant nowadays, embedded in grease, as it has some very long lasting non volatile properties that are very effective.

I've an odd connection with Filtrate also as my father swore by it for use in a Vincent Black Shadow he owned and raced. He got a third place on it in the 1953 TT 1000cc class using that oil which was provided to him by the factory. Think I've still got the letter of agreement from the oil factory.
More recently, I was standing talking at a bike meet to someone with a Vincent Black Prince, and was recalling my father's bike of which I new the reg no, he made just one phone call to someone that knew of Vincents currently owned and that person is the current owner of my father's bike. What a stunning coincidence.

Nigel.

Offline Bryanj

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Re: Zinc content in oil
« Reply #25 on: June 27, 2017, 07:34:57 AM »
When i worked for Frazer in Glos we used to buy Filtrate 10w40 in 5 gall drums from the Suzuki dealer in Bristol (Used to sell pushbikes as well) as he bought it by the truck lload and it made it cheaper than anybody elses for shop use and met Honda specs. Dont remember any collodial graphite in it though

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Re: Zinc content in oil
« Reply #26 on: June 29, 2017, 10:24:44 AM »
I think there are, as you say Bryan, two distinct parts to that story as filtrate. The normal oil that the brand name applied to and the colloidal graphite stand which may have been incorporated into the oil in earlier years or added as a package to any oil from a separate can to, in effect, dose your oil of choice.
I guess that with the advent of more complete filtering systems the days of adding something of that partical size to engine oil would largely disappear. As Ash found out then,  it will all end up in the filter system.

There was an interesting documentary last year on the graphite industry centred around Whitehaven in Cumbria,  as they found that molds for cannonballs when coated with it enabled a particularly clean release of the cast balls. This allowed them to be made much closer to consistently spherical,  this along with then allowing a much more accurate choke in the canon barrels vastly improved our naval warfare capabilites with the attendant outgunning of opposition.

More relating to the bikes on this forum, I don't consider anything ( certainly within the 4 cylinder bikes) mechanical to give the oil a hard time resulting in oil condition deteriorating to the point that it would be considered unable to lubricate properly.
That doesn't mean that something else is not in operation that does.

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Re: Zinc content in oil
« Reply #27 on: July 19, 2017, 06:58:36 PM »
To move on from the mechanical effects imposed on the oil in these bikes, I feel it's the combustion strategy that causes the oil life to be quite short.

There's a basic problem running multiple slide carbs to fuel these engines. I can taken a guess as to why the design originated, Honda's mimic of their sixties race bike technologies leveraged, in marketing terms,  to deliver road versions of that track success.  Pretty good it is too.

With one carb per cylinder there is no air volume passed through that carb except for its own cylinder, obviously,  so the vacuum can't be moderated as perhaps a single carb for multi cylinder would. In addition, a simple slide carb has what I'd consider to be "symmetrical " fuel metering in that it's a straight correlation of air vacuum to the amount the main jet is allowed to flow by it and it's needle geometry.
This is where it gets more interesting. For complete burn of fuel you need an ideal ratio of 14.7 parts air to 1 part fuel ( think that's right)  and which is known as the stoichiometric ratio. If you don't run this, and many engines don't, then any excess fuel is not burnt which leaves it to go out of the exhaust port or past the rings into the oil.
The specific problem with slide carbs as fitted to many of these bikes is that to get the engine to accelerate well then you may need to get down toward 11  to 1 ratio to light it up and make it respond fast to the throttle being opened,  and if you jet it like that it'll have to run at that ratio even without load, ie trickling along on part throttle. I think it's worse than that though, to get the mixture rich enough to respond well is also tempered by the transient characteristics of this carburettor arrangement. If the engine is running slower revs and you open the throttles wide instantly then the vacuum drops as the carb is wide open and the engine is not sucking much. Sooooo, you have to in effect compensate for this small part it time by using an even greater supply of fuel if you want it to really jump in rpm. All of which can't be mitigated for steady state cruising. In other words they run constantly too rich from theoretical stoichiometric by quite a long way. And also why PD carbs offer something of a solution in adding fuel just for the acceleration phase and allowing more moderate cruising to be accomplished at something toward a normal fuel air ratio. In this sense they are simply better for the engine and a blueprint (a crude one)  for modern fuel injection systems. In other words, asymmetric fueling based on engine load and response requirements.
Interestingly the CV carbs do something similar. I'm guessing again that Honda didn't want to use these for their first fours as they may not have been considered sporting enough / or offer the level of response the design team asked of their project. When you open the throttle on CV carbs, the butterfly controls demand from rider and in response the slide is raised via engine vacuum so aiming to avoid the transient vacuum loss you get on slides when you walk the throttle wide, aka Constant Vacuum. They also go further as I understand it in that the slides are usually damped going open so that when the engine vacuum s rising the slides lag behind this curve,  this momentarily causes a higher vacuum peak just under the slide which pulls more fuel in to give a richer mixture just when needed and until the slide position catches up with engine vacuum. You could view the throttle butterfly as a request system that allows the engine cylinder vacuum to be allowed past and influence the slides which then accelerate the engine.

The CV types are useful as a comparison to the slide type carbs but also have relevance to the original question about the 450 CB.

So in realty on the fours,  I think the oil is prematurely trashed by not being able to run a more optimal mixture. They are far more orientated toward race engine running than just cruising about.

Offline Green1

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Re: Zinc content in oil
« Reply #28 on: July 20, 2017, 09:11:47 PM »
I'm to tiered too read this at the moment but from what I understand wasted fuel gets into the oil thus fecking it up.

I do wonder how long modern Diesel engines will last with DPF's.
If there stopped half way through there regen they dump the unburnt Diesel into the sump.
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Offline hairygit

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Re: Zinc content in oil
« Reply #29 on: July 20, 2017, 09:27:19 PM »
But diesel IS oil, albeit of a very thin nature, check the V5 of a diesel vehicle, for fuel type it states "Heavy oil".

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