2T as upper cylinder lubricant?

OK, I’m clearer now what happening with the cat. Its cruder than I’d realised. Thanks for the explanations.

Re 2-stroke oil as UCL, OK, maybe not then. In my defence:-

(a) The Chinese BMW clones I originally thought of it for are probably as far as it is possible to get from “modern” in a (current?) or at least recent production engine. (Damn, now I’ve said that I want one, I knew that would happen). IIRC they suffer from poor (splash) oiling, poor cooling (the flathead is just a slab of metal without oilways) and poor metallurgy, so I thought 2-stroke oil (and maybe water inspiration) might promote survival.

(b) My impression is that 2-stroke oil is mysteriously remarkable stuff, given that, at the dilutions its used at, its viscosity must be very close to that of petrol.

The only way I can see that it can work is if it binds to surfaces/hot spots, so that its effective concentration is much higher than its bulk dilution would suggest. I’ve read somewhere that’s how castor oil, (used of course as a race 2-stroke lubricant and in other total-loss systems, such as in a Sopwith Camel rotary engine) works, turning its thermal instability to advantage.

If that is how it works, I thought there might be a dilution level where the leaning was tolerable/insignificant, but there was still a protective effect. I’d expect this to be a higher dilution to that in a “normal” 2-stroke premix.

Of course it would be possible to richen the mixture to compensate, but maybe non-trivial in a non-carbed vehicle.

I did some webcrawling. Its actually discussed quite a bit, though inconclusively, with people claiming various benefits, such as mileage improvements, which I find it impossible to believe they actually measured. Most people have no clue as to thier mileage.

Since most of the discussion is from the US, quantities tend to be discussed in terms of oz/gal, which I can’t be bothered with, but people using 2T in modern 4 stroke vehicles seem to be using it at 1:500 by volume or less.

I’d guess leaning wouldn’t be much of an issue at that kind of dilution, though I don’t know that for a fact.

Inconclusive discussion/argument on Toyota 100 series forum, lots more unsupported opinions on “Bob is The Oil Guy” but it gets pretty tedious.

http://forum.ih8mud.com/100-series-cruisers/234292-fuel-additives-2-stroke-oil-v8.html

A UK Ducati Monster Forum

http://www.ukmonster.co.uk/monster/archive/index.php/t-7792.html

quotes a Silkolene chemist

"UCLs on the other hand can be useful. After all, 2-strokes in effect run entirely on UCL. So the best UCL’s are 2-stroke oils! I always tell people to use a decent 2-stroke at 0.5% or 1%, because they are superior to the UCL’s sold as UCL’s if you get my drift. A litre of Super 2 Injector or Comp-2 will be better than a cupful of cheap mineral oil dyed red (no prizes for guessing the name) any day.

Vee engines (twins, to V8’s) benefit from UCL’s because the upper walls of the RH cylinder bank, looking from the front, always run dry. Think about it!"

Seems reasonable to me, but yer pays yer money…or you dont.

Larg diesel two strokes inject oil trough drillings in the cylinder.
4 or more holes are drilled around the cylinder and deep croves are cutt in the cylinder wall where the oil can spread around the cylinder. Ben in use for 80years or so.
The oil use is close to zero since it’s aplied directly to the liner and not mixed with the fuel so it do it’s job instead of just burning up like in a scooter engine. How much of those 1-3% do you think ever touch a metal surface that is subject to mecanical friction?

[quote=“Stian”]Larg diesel two strokes inject oil trough drillings in the cylinder.
4 or more holes are drilled around the cylinder and deep croves are cutt in the cylinder wall where the oil can spread around the cylinder. Ben in use for 80years or so.
The oil use is close to zero since it’s aplied directly to the liner and not mixed with the fuel so it do it’s job instead of just burning up like in a scooter engine. How much of those 1-3% do you think ever touch a metal surface that is subject to mecanical friction?[/quote]
Yes, and a lot of high-output gasoline engines have oil jets in the block aimed at the underside of the piston crown, partly to cool the pistons and partly to provide positive lubrication to the cylinder walls that would otherwise survive on random splashes from the big end bearings and oil that has been smashed into mist by the spinning of the crankshaft. It doesn’t cause oil consumption issues because it’s applied below the oil control rings.

UCL applied in ratios like 1:500 wouldn’t lean the mixture unduly. Not sure what effect is has on the fuel system components like high-pressure pumps, filters and injectors however. Would oil cause premature injector fouling (for example)? I don’t know. Put it the other way. Do modern engines suffer from rapid cylinder and piston wear? I wouldn’t say that car engines do. Most seem to be able to hold a good seal well into the 150,000 ~ 200,000km range, at which time so many other things are worn out as to make overhaul an impractical option, relative to the cost of obtaining a good used engine. Motorcycles are another matter, with very high operating speeds and brake specific outputs, but motorcycles tend to die accidental deaths or become obsolete for other reasons.

Like Ed, I doubt anyone would have come up with hard data to support the idea that adding a little 2T does in fact improve gas mileage. I doubt anyone has done a serious study on this.

[quote=“Stian”]Larg diesel two strokes inject oil trough drillings in the cylinder.
4 or more holes are drilled around the cylinder and deep croves are cutt in the cylinder wall where the oil can spread around the cylinder. Ben in use for 80years or so.
The oil use is close to zero since it’s aplied directly to the liner and not mixed with the fuel so it do it’s job instead of just burning up like in a scooter engine. How much of those 1-3% do you think ever touch a metal surface that is subject to mecanical friction?[/quote]

In principle, its quite clear to me that “conventional” 2 strokes are impossible. Like that myth of the bumblebee, there is absolutely no way they can work.

However, observation shows that even my RZR works quite well sometimes, so, like that myth of the bumblebee, the processes involved must be more subtle and complex than at first appears.

One possibility, as I suggest above, is that the oil binds selectively to hot spots. I’ve seen this suggested as an explanation for the high performance of castor oils. I don’t know if its a general 2-stroke oil behaviour, but if it is, the answer to your

“How much of those 1-3% do you think ever touch a metal surface that is subject to mecanical friction?” (rhetorical?) question would be

" I don’t know, but a lot more than 1-3% locally. Otherwise it wouldn’t work."

[quote=“Ducked”]
“How much of those 1-3% do you think ever touch a metal surface that is subject to mecanical friction?” (rhetorical?) question would be

" I don’t know, but a lot more than 1-3%. Otherwise it wouldn’t work."[/quote]
No. Almost all of the oil a conventional two-stroke ingests goes straight out the exhaust port partially burnt and without ever having touched a metal surface. It is amazing when you think about it. The motor uses so little of the stuff and yet doesn’t seize.
Mind you, in terms of cylinder/ring life a two-stroke is probably the shortest-lived thing ever made, though much of the problem is the ring package passing by the ports. Anyway, that’s another discussion.
I do believe you are right about castor oils and how they have affinity for hot areas. I used to use Castrol R in the two-stroke race bikes I tuned / prepared back in the day and the amount of gunk that would build up in the top ends was amazing. About four race weekends would put so much varnish into the ring grooves the rings would stick and cause massive blow-by. Castor oil when heated turns first into a thick and hard varnish. Then it burns into a very hard coke. I believe the varnish is very slippery. It’s also very difficult to remove. During a routine rebuild I’d be replacing the rings anyway, but the pistons would be a bitch to clean up.

I didn’t get my locally edit in in time, which maybe slightly clarified what I was trying to say.

I accept that most of the oil is a merely a non-lubricating pollutant.

What I’m suggesting is that the local effective concentration of the oil at friction sites is higher than its bulk dilution of 1-3%, otherwise it wouldn’t work.

A couple more “what ifs”, I’m afraid, and not UCL, but I doubt they merit their own thread.

Suppose that, in a conventional 2-stroke, you alternated 2S (I’m indulging myself in a bit of defiance of the “2T” convention, because I don’t understand where it comes from) with a castor content, and a mineral-based (?) conventional 2S. Could you get a bit of “non-stick coating” from the castor, which would then be gradually worn off (or at least not build up much further), until you repeated the castor treatment?

Alternatively, using a different oil as a dilute premix and a lube pumped oil would allow you to alter the oil composition as the revs increased, say using a fouling -resistant oil as the premix and a high -performance but cokey oil in the pump. Could have advantages, though I dunno if the information on oil composition and behaviour is available to put together an optimal plan, and its maybe its too complicated to be worthwhile.

[quote=“Ducked”]A couple more “what ifs”, I’m afraid, and not UCL, but I doubt they merit their own thread.

Suppose that, in a conventional 2-stroke, you alternated 2S (I’m indulging myself in a bit of defiance of the “2T” convention, because I don’t understand where it comes from) with a castor content, and a mineral-based (?) conventional 2S. Could you get a bit of “non-stick coating” from the castor, which would then be gradually worn off (or at least not build up much further), until you repeated the castor treatment?
[/quote]
No, I don’t think so. Castor oil varnish building up on the piston skirt is one thing… the friction against the bore would keep that to a minimum. The bigger problem is the varnish that builds in the ring gap. The rings have to be able to move to do their job. The varnish glues them in place. I don’t think any amount of detergent in the engine oil will prevent that. Then there’s the hard coke which will eventually form on the piston crown. Oh, and there’s the other little problem that vegetable and minerals oils react to each other. Forgot about that. :no-no:

BTW, 2T is short for 2-Takt. German. Remember it was a couple of German engineers that really developed the technology, but it was stolen by the Allies after the war and we wasted it on horrible devices like the BSA Bantam. :laughing:

[quote=“Ducked”]
Alternatively, using a different oil as a dilute premix and a lube pumped oil would allow you to alter the oil composition as the revs increased, say using a fouling -resistant oil as the premix and a high -performance but cokey oil in the pump. Could have advantages, though I dunno if the information on oil composition and behaviour is available to put together an optimal plan, and its maybe its too complicated to be worthwhile.[/quote]
You took the words right out of my mouth. :wink:

[quote=“redwagon”]Oh, and there’s the other little problem that vegetable and minerals oils react to each other. Forgot about that. :no-no:
[/quote]

Thats interesting. I know veg oils are quite reactive but I thought the mineral oil would be too inert to react much with them. Diesels running SVO can end up with gelled sump oil, but I dunno if it reacts, I’d thought it might just be contaminated with cross-linked VO.

In a 2T (ach so, good to know) with a no-sump, total loss lube system, the opportunities for reaction seem quite limited.

Well, its not all that complicated, IF it offered any advantage (which of course is the doubtful bit). Peoples complication threasholds vary strangely.

Frinstance, the commonest reaction to my initial description of the Mk1/2 Eds Oiler was, surprisingly, not:-

“Yore a FAHKIN GENIUS mate, those Scottoiler comedians must be bottlin it”

but rather

“Overkill” (a drinking straw?) or “Too much effort” (a DRINKING STRAW??)

Round about the same time, SBL was reporting spending quite A LOT of money and time getting people to turbocharge not one but two vehicles that were unsuitable, didn’t need it, or both. His money, he can of course spend it how he likes.

But it was the drinking straw that was judged oberkill in the court of public opinion. Truly, there is nowt so queer as folk. :ponder:

But I’m not bitter :slight_smile: just a little off topic, again.

I don’t think two stroke oil bind to hot spots in any magical way.
The most hot place in a two stroke cylinder is the exhaust port where all the gas exits.
This is also where fresh mixure exits before being pressed back by the exspansion chamber so there would be more oil applied here by natural ways.

90% of all seizures in a 4 stroke start at the bottom or top because this is the place where the piston speed is at it’s lowest and the oil therfore the hydrodynamical lubrication is lost (ring speed it to low to aquaplane on the oil and get metalic contact)

On a 2 stroke the densety of oil would be much higher on top dead center and all the fresh oil would enter at bottom dead center so I gues this would be a factor that the places need it most will get it most.

My :2cents:

[quote=“Stian”]I don’t think two stroke oil bind to hot spots in any magical way.
The most hot place in a two stroke cylinder is the exhaust port where all the gas exits.
This is also where fresh mixure exits before being pressed back by the exspansion chamber so there would be more oil applied here by natural ways.
[/quote]
Castor oil isn’t magically attracted to any particular place, but the way it decomposes in high temperatures is a bit different from mineral or synthetic oils. It turns into a substance with a pretty low coefficient of friction, helping lubricate that spot. Mostly it just has a very high film strength which just resists breaking even when stretched extremely thin. The disadvantage, as I mentioned, is that is does coke a lot in places you don’t want it to. Synthetics have good film strength but don’t coke as easily, which makes them much more suitable for street-going engines.

Your point about the exhaust port is a good one, as that is the hottest part of the engine and much of the oil charge is going to pass through it twice, giving much more of it a chance to settle there. OTOH, the extreme heat does help keep it clean, as does the speed at which the gases are flowing through there, especially as the port is opening. This is why much more crud accumulates toward the end of the exhaust, where speeds and temperatures are much lower, allowing more oil to condense on the pipe.

[quote=“redwagon”]
Castor oil isn’t magically attracted to any particular place, but the way it decomposes in high temperatures is a bit different from mineral or synthetic oils. It turns into a substance with a pretty low coefficient of friction, helping lubricate that spot. Mostly it just has a very high film strength which just resists breaking even when stretched extremely thin. The disadvantage, as I mentioned, is that is does coke a lot in places you don’t want it to. Synthetics have good film strength but don’t coke as easily, which makes them much more suitable for street-going engines.[/quote]

I know some race oils have some special formulas, but I also know there are disadvantages so I keep away from them.
I’m too lazy to dismantle my engine and clean it evey week.

[quote=“Stian”]

I know some race oils have some special formulas, but I also know there are disadvantages so I keep away from them.
I’m too lazy to dismantle my engine and clean it evey week.[/quote]
Exactly. I ran castor oil in one street bike, and learned the hard way. I was very young, and the word ‘racing’ was just too seductive. These days I would run street 2T in a race motor before the opposite.

[quote=“Ducked”][quote=“redwagon”]Oh, and there’s the other little problem that vegetable and minerals oils react to each other. Forgot about that. :no-no:
[/quote]

Thats interesting. I know veg oils are quite reactive but I thought the mineral oil would be too inert to react much with them. Diesels running SVO can end up with gelled sump oil, but I dunno if it reacts, I’d thought it might just be contaminated with cross-linked VO.

In a 2T (ach so, good to know) with a no-sump, total loss lube system, the opportunities for reaction seem quite limited.

[/quote]

Ah. I suppose I should add “if delivered at different times” (which would be difficult to arrange without completely emptying the lube system on swap-over.) If they were mixed in the combustion chamber, even the mineral oil is likely to be quite reactive, since its burning.

I don’t know what ‘2T’ or ‘upper cylinder lubricant’ are.

Probably isn’t of much interest to you then. Doesn’t make you a bad person.

Hell, even I didn’t know what 2T meant until it was explained to me above. It means 2 takt, apparently. German.