2 stroke oil - composition??

[jrustles]

I posted this in the wrong forum yesterday, so I'll try here!

Does anyone know the general composition of 2 stroke oils?
I can't for the life of me find a VOA.
The extent of my speculation is that the 'ash' formulas contain zinc and other AW in some form.
And the ashless? It's a mystery. Perhaps some type of esters?

Expert input is valued. Even speculation is welcome, as it can stimulate discussion !

 

[bmwtechguy]

Ash content refers to the metallic AW additives IIRC. Most if not all 2-smoke oils for water-cooled engines such as TCW3 spec are ashless. I will guess that there are some ester-containing additives (and/or base oils) that are used in place of the metallic AW additives. Also, if my memory serves, the ashless additives cost more to give the same AW perfomance as metallic additives, and leave behind less deposits (burn cleaner). I am sure that Molakule or others can elaborate and correct any inaccuracies here.

On another note, I was looking at the tech sheet for Schaeffer's new synthetic 2-stroke racing oil and it is listed as ashless and as suitable for both water-cooled and air-cooled engines, including those that utilize power valves in the exhaust. Have never used it, but sounds like a one-size fits all product. I guess with today's high perfomance additives, that is now possible? Amsoil has at least 4 different 2-stroke lubricant formulas in comparison.

 

[carwreck]

2T Voa comparison.... Very low phosphorous/zinc additives.
http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2491605

Example of oil contents...
Per the item description, "Super-M is a blend of clean burning petroleum base oil, synthetic polyolester, polybutene, anti-scuff/anti-wear compounds and a new additive that keeps rings, power valves and the exhaust tract "carbon free"

 

[beanoil]

Depends upon the oil. Cheaper 2 stroke oils are bright stock and solvents, with some AW adds. Expensive oils will have an ester base, a smaller percentage of solvents (maybe) and an AW add pack. Some oils are castor based, some are castor/petroleum blends, some are petroleum blends. Injector oils will have a slightly lower weight (say 20 or 30 weight) while one of the most famous 2T oils, Castrol A747, is a 50 weight.

 

[MolaKule]

Quote:
And the ashless? It's a mystery. Perhaps some type of esters?



The ashless or low ash oils contain very little metallic components except for the small amount of detergent, which is a soft ash.

The base oils for ashless synthetic oils are usually esters, PAO's, and vegetable oils.

Other additives you will not see in a VOA are polyisobutylenes and ashless dispersants.

Then of course, there is usually a solvent about 1% to 10% by weight usually of the form of a Stoddard Solvent. While this solvent has often been misaligned, it is necessary in order to help the 2-cycle oil disperse and mix properly with the gasoline.

The viscosities of 2-cycle oils are limited to a low of 6.5 cSt and go all the way up to 12 cSt.

 

[bmwtechguy]

The real 2-stroke question of the day for me is, why do the contents of the bottles of synthetic 2 stroke oils consistently shrink if left unused on the shelf for 5 years or more? Where is the matter/fluid volume going? I have seen this with both Amsoil and M1 synthetic 2-stroke oils. I finally gave away the last few bottles I had to a couple good friends with various 2 stroke engines. I did not feel good taking money for them because the bottles looked so shrunken.

 

[lars11]

Haha, I have seen this in most of my old oil and chem bottles too. They shrink, wheter in three years or 15 years, they look like someone sucked the air out. Must be some light fractions evacuating through the plastic bottles. Or, the plastic in the bottles expanding??(?) Or, the oil actually absorbs some air?

Anyone? Interesting question, at least when there's nothing else to do...

 

[jrustles]

Good info guys!
Carwreck, how did I miss those VOAs? Thanks for the link
Molakule, thank you very much for the definitive on 2T oils.

I'm actually surprised to see the Ca in there.

So to summarize, more expensive oils have esters, and are mostly ashless or low-ash, while more traditional oils rely on mineral oil with metal AW and solvents for miscibility, yet produce ash.

Anyone think the Ca could potentially cause an issue if used in the gas of injected 4-stroke vehicles? What about some ashless were to wind up in a conventional crankcase? Would it break down into gum and goop?

 

[MolaKule]

Quote:
I'm actually surprised to see the Ca in there.

So to summarize, more expensive oils have esters, and are mostly ashless or low-ash, while more traditional oils rely on mineral oil with metal AW and solvents for miscibility, yet produce ash.



I think the calcium levels in those analyses are about 2X too high.

All 2-cycle oils, whether mineral base or synthetic bases, use a solvent.