What 2 Stroke?

[Stubby]

Think it was my theory . seem to remember saying that . I run Redline at 50:1 with Aspen 4 .

[GardenKit]

We all have different theories, but I have to admit to being in the 50:1 camp.

As has just been said, both the oil companies and the saw manufacturers are confident with 50:1, and they have the best interest of the saw at heart, and as has also been said the 50:1 mix is already stronger than is needed.

 

And as to the 'theory', that's not just theory, its fact. A 40:1 mix has 0.5% more oil and 0.5% less fuel in a given volume so it will be just a bit weaker unless tuned out, so will run a bit hotter.

 

But there is also another downside too adding a bit more, and that is the increased build up of oily deposits in the exhaust ports and exhaust.

 

But to be honest, 98% of the mix is petrol, and its the petrol that causes most damage in an engine. Even the best oil cannot make up for crap fuel.

 

So whatever oil you choose to use, make sure you only mix with fresh, low ethanol, fuel (keep clear of Tesco petrol) and ensure that you never use petrol more than 30 days old. Seriously.

[TGB]

Or just do as Stubby does or go with Aspen 2 or similar premixed alkylate fuel.

[Little Al]

A local saw docter told me to only use Husky oil in Husky saws as they run hotter and faster and other oils are not designed to cope. I reckon he could be right as I've a friend that has got through two engines in two years on a new Husky 550 using Stihl oil.

SG

 

I think he's been on a Husky " brain washing course"there are 2 smoke mix oils out there that are equal, if not superior, to husky oil.A 100% synth Jaso FD rated oil will perform to equal / better than what he is pushing. A thing to remember is that oil labeled by saw maker is blended for them by an oil company, & the oil company will advise on the blend, so if they can advise on the blend it follows that oil marketed under their own brand will contain the "goodies" As an aside some of the smaller oil company' cannot afford the cost of the JASO test but produce oil as good/better than the rated stuff But it's a bit of a black art sussing out what oil this is if you stick with a FD rated oil you will be good to go, there are less pricey brands that will do an equal/better job. A bit of a search through the oil specs will give you an idea.

[Little Al]

We are a commercial set up & run our saws approx 8Hrs a day 5/5 to 6 days a week for 10.5 to 11 months a year we change the saws with the most hrs on them every 2/2;5 years we mix at 40/1 & the 15 years Iv'e been servicing the saws we have not suffered an oil related saw failure I'm not saying that this is the correct & other mixes are wrong it's just the way we do it & the outcome

[TimberCutterDartmoor]

A local saw docter told me to only use Husky oil in Husky saws as they run hotter and faster and other oils are not designed to cope. I reckon he could be right as I've a friend that has got through two engines in two years on a new Husky 550 using Stihl oil.

SG

 

 

Fair enough Steve, you know I defer to your knowledge on anything 2 Stroke.

 

As I understand it though, high quality synthetic 2 stroke oils already have that factor built in. I've read that RL for instance would be fine running on a much leaner mix.

 

Otherwise someone accidentally mixing at 51:1 would instantly cook their engine.

 

Indeed. The better the oil the wider the margin of safety with insufficient UCL in the mix; I would hazard that castor and RL would survive the worst lean-off / over-rev / over-heat / scenario.

 

Think it was my theory . seem to remember saying that . I run Redline at 50:1 with Aspen 4 .

 

Ditto. Ultimate Fuel.

 

I think he's been on a Husky " brain washing course"there are 2 smoke mix oils out there that are equal, if not superior, to husky oil.A 100% synth Jaso FD rated oil will perform to equal / better than what he is pushing. A thing to remember is that oil labeled by saw maker is blended for them by an oil company, & the oil company will advise on the blend, so if they can advise on the blend it follows that oil marketed under their own brand will contain the "goodies" As an aside some of the smaller oil company' cannot afford the cost of the JASO test but produce oil as good/better than the rated stuff But it's a bit of a black art sussing out what oil this is if you stick with a FD rated oil you will be good to go, there are less pricey brands that will do an equal/better job. A bit of a search through the oil specs will give you an idea.

 

That's right on the whole BUT there are FC oils that out-perform FD oils in lubricity terms such as RL; simple reason the basestock is clean enough not to require the anti-oxidation and other additives / detergents required for FD.

 

FTR, RL is widely regarded as the best money can buy; there are some Motul / AMS / Silkolene products hot on their heels, but none are 100% POE basestock.

 

Echo Power Blend is higher performing than Stihl Ultra and Husky. Not lower smoke tho, despite being FD.

 

Black art lol.

[R Mac]

Think it was my theory . seem to remember saying that . I run Redline at 50:1 with Aspen 4 .

 

Hi Stubby, glad you weighed in on that one but I heard it from someone else in person, quite possibly it was mentioned when I was doing my basic tickets.

 

FWIW I use Oregon Semi Synth at 50:1 with regular unleaded (not supermarket) in all my saws/trimmers/blower etc, even the cheap Chinese ones that are supposed to run 40:1.

[Sveriges]

Husqvarna XP oil that you buy today not the previous older version was produced with the new 5 series engine and specifically for that purpose by an oil company in Sweden. Your all aware of the power and performance of the 550 560 etc and as a result husqvarna required an oil for the job.

 

Of course there are other oils that also do the job just fine but there are far more that do not. When they say use XP it's not marketing rubbish. You only have to strip an engine to immediately see the signs as to what sort of oil it's had through it. bearing failure on these saws has been known amoung other things and the main cause of the failures is heat. The right oil means less heat and less failures. I'm only speaking of one brand and one engine type but just as an example and I think as long as its of quality and suited to the application then there's no need to worry.

[spudulike]

I run 50:1 as that's what both the saw manufacturer and the oil manufacturer suggest.

 

I heard a theory regarding running e.g. 40:1 that I'll share, not entirely convinced TBH although I guess it sounds plausible, I didn't think too much about it as I wasn't changing from 50:1 any way.

 

The Theory, If you mix at 40:1 rather than 50:1 there's less petrol present in any given amount of metered fuel being delivered to the saw, the amount of metered air remains the same so at 40:1 the fuel has a greater percentage of oil and a smaller percentage of petrol. If the amount of air remains the same but you reduce the amount of petrol the mix is leaner, so the saws runs leaner at 40:1 than at 50:1.

 

Like I say, not my theory, not sure I'm convinced either way and in any case I'm running 50:1 as that's what the manufacturer suggests. I'd be interested in your take on the theory though Spud.

 

Using that theory, if you run a 20:1 mix, you are likely to lean seize the engine:confused1:

 

The real theory is you are keeping the same amount of air and are replacing a small amount of fuel with oil. The oil will help lube the engine and we are talking small percentages and is unlikely to make much difference to the tune of the carb.

 

Leaning the engine usually refers to when the amount of Fuel/oil is reduced giving a larger percentage of air causing a significant rise in temperature due to the extra air making the fuel burn hotter and faster. In your example, you are keeping the same ratio of fuel/oil mix and air and it is just the ratio of fuel and oil that has changed!

[R Mac]

Using that theory, if you run a 20:1 mix, you are likely to lean seize the engine:confused1:

 

Not if said engine is designed to run 20:1, I only mentioned I'd heard it.

 

The real theory is you are keeping the same amount of air and are replacing a small amount of fuel with oil. The oil will help lube the engine and we are talking small percentages and is unlikely to make much difference to the tune of the carb.

 

Leaning the engine usually refers to when the amount of Fuel/oil is reduced giving a larger percentage of air causing a significant rise in temperature due to the extra air making the fuel burn hotter and faster. In your example, you are keeping the same ratio of fuel/oil mix and air and it is just the ratio of fuel and oil that has changed!

 

Yeah I understand what running lean is and what the result will be.