Thread: which 50-60cc Stihl chainsaw

Originally Posted by bigbear

@No.3 what category would you put the stihl oils in?

Stihl oils I believe are supplied by Castrol, love them or hate them Castrol are one of the biggest suppliers of oil on the planet and all that means is that you are going to end up with more instances of failed equipment that have been run on Castrol supplied oils. No issue with Castrol myself - and one of the issues with two stroke gear like chainsaws is when it fails you are never quite sure whether the failure is related to the lubricant failing or it's a lean condition through a seal failing or other air leak, or a carb failure, or the operator clusterflucked it my not mixing the fuel right or some other issue. Regardless of what caused it, the operator always blames the oil and often the mechanic or retailer encourages this as it means they can sell something else when they sell the new tool to replace the buggered one.

I will make the comment that lubricant failure in properly mixed fresh two-stroke fuel with the correct ratio is such a rare event that I'd almost say that these days with modern reputable brand oils, it's not going to happen. Period. What is more likely in my belief, is that the operator gets their ratio amounts mixed up and think that they've mixed 50:1 or 40:1 or whatever the ratio is - but is actually hitting 60:1 or leaner and then either running the tool in overload conditions or loaded up at half throttle with poor cooling airflow and ending up with an overheat condition. Whatever oil you use, won't prevent that sort of failure (abuse)! What I saw once is someone mixing two-stroke fuel at a site by the 20L volume. What they did is a fairly easy maths mistake of using the oil amount for a 50:1 ratio of 20L total and adding 20L of fuel to that amount of oil. I think it ended up at about 58:1 which was just lean enough to cause bearing failures on a couple of 90+cc saws - as 7mmsaum suggests that's near on half the amount of oil that is safe for the bigger saws for bearing life. One very pissed off company owner, and a day of no work with a 100ton crane sitting idle! Another thing I try and avoid is running saws for long periods with the bar sunk at full depth and the powerhead hard up against a flattish surface. What can happen here is hot exhaust gas getting recirculated into the fan/pull start cover so you aren't getting the full cooling airflow of fresh cold air over the cylinder fins.

As far as oil I have used Mobil oil in marine applications, Stihl/Castrol oils extensively in fire fighting pumps, and have gotten a few other interesting brews when I've brought chainsaws as a fixer upper type thing. One of the most interesting ones I have is a Mobil two stroke brew coloured red, it smells strongly of strawberry lipgloss - talk about bringing back memories of dodgy days as a young fella chasing idealistic young ladies around attempting to get sticky fingers! I mix the hard way, 1L at a time with a little mixing bottle from Bunnings and into a larger 5L container and I use 40:1 ratio in everything. I do it this way, as if I fark up the ratios it's only 1L hopefully and and into the bigger container. It's a little slower but repairs are dearer haha. Touch wood, I have not had a problem since doing this.

the wee oil despenser bottles with 1 litre of oil and a smaller bottle linked by tube are gold....and the good ones already have your amount per litre on them....
Ive written it on the 5ltr 2stroke can with felt pen...... takes the remembering bit away LOL....I really prefer blue or green oil to red,purely so I cant double mix it again

This thread has gotten off track drop OP but getting fuelil mix right isn’t difficult. Have used this formula since 1976. Same formula as taught at trade school in ‘79.
Take number of litres of fuel, multiply by 1000, divide this figure by your mix ratio and this gives you the amount in mls ( millilitres ) to add. eg. 50:1 mix.
5 litres fuel x 1000 = 5000, divide this by 50 = 100 mls oil to add.
Works for any ratio, has done all these years and never had an engine issue due to fuel mix.
I work in the trade and in the case of suspected engine seizure the first thing we do is carry out a fuel burn comparison test: straight fuel: known fuel mix: fuel mix from engine in question. Quickly shows potential fuel mixing cockup. Move on to other engine checks after that if necessary.
We have forest crews using Stihl oil no problems, two operating 30 saws each plus others using up to 10 or more. Opposition has similar numbers running Husqvarna saws/oil. Haven’t heard of any problems from them. We both get customers who have dipshit moments and straight fuel their gear.

Over here its rare that anyone mixes their own fuel any longer,its all store bought premix alkylate stuff. It is expensive but its awesome,easy on the machine and produced no smoke.Plus it never goes off,I had a backpack blower that had been out of service for 7 years.I primed the carb and it fired straight up .

Just dont use it in a primus.

Originally Posted by norsk

Over here its rare that anyone mixes their own fuel any longer,its all store bought premix alkylate stuff. It is expensive but its awesome,easy on the machine and produced no smoke.Plus it never goes off,I had a backpack blower that had been out of service for 7 years.I primed the carb and it fired straight up .

Just dont use it in a primus.

When using chainsaws there what would be your normal air temperature ?

Originally Posted by 7mmsaum

When using chainsaws there what would be your normal air temperature ?

Not sure over all, here is a graph that showes monthly averages.I dont tend to work dec to march if I can help it.

Those temps will keep your saws cooler

In direct sunlight and sawing close to the ground we are often in 30/35 to 40 degrees C here in Hawkes Bay NZ

It’s likely your premix oil ratio is higher (less oil) than what we would get away with

Originally Posted by woods223

This thread has gotten off track drop OP but getting fuelil mix right isn’t difficult. Have used this formula since 1976. Same formula as taught at trade school in ‘79.
Take number of litres of fuel, multiply by 1000, divide this figure by your mix ratio and this gives you the amount in mls ( millilitres ) to add. eg. 50:1 mix.
5 litres fuel x 1000 = 5000, divide this by 50 = 100 mls oil to add.
Works for any ratio, has done all these years and never had an engine issue due to fuel mix.
I work in the trade and in the case of suspected engine seizure the first thing we do is carry out a fuel burn comparison test: straight fuel: known fuel mix: fuel mix from engine in question. Quickly shows potential fuel mixing cockup. Move on to other engine checks after that if necessary.
We have forest crews using Stihl oil no problems, two operating 30 saws each plus others using up to 10 or more. Opposition has similar numbers running Husqvarna saws/oil. Haven’t heard of any problems from them. We both get customers who have dipshit moments and straight fuel their gear.

Ha, I've been using that formula for a while having sort of worked it out myself using the phone calculator when I'm out away from mixing charts or have to mix a weird amount for some reason.
Thought I was clever too, didn't realise they used to teach it haha.

Have you noticed the die breakdown in older mixed fuel? By that I mean fuel mixed with either red or blue oil that's left for a long period of time turning a golden shade with a smell of old fuel? I've struck that a couple of times recently with old fuel that's been stored in the back of sheds and then found in the can - what's this then? It leaves an oily stain on a evap test, flames like two stroke but has somewhere along the line dumped it's colour. Odd...

One thing with the burn test I've found is some of the newer synthetic oil types are quite a bit lower in density than the older mineral oils. The burn test can make it look like the mix is quite skinny but is actually mixed to spec. Will still tell you straight off if it's a dipshit moment and straight-gassed but not accurate to tell you the actual mix ratio. I've been sort of looking for a repeatable way to get an accurate volume of oil in a mix, but even in a lab it's not straightforward to get an actual ratio and they need to know what the actual brand and type of oil is for comparison checks (the oil density issue again).

Originally Posted by 7mmsaum

Those temps will keep your saws cooler

In direct sunlight and sawing close to the ground we are often in 30/35 to 40 degrees C here in Hawkes Bay NZ

It’s likely your premix oil ratio is higher (less oil) than what we would get away with

Those temps would keep me cooler, I'm not blaming the saws at all. Brrrrrr... Not enjoying the cold at the moment - it's an official 'I'm getting old' moment. Only run into the premix fuel once, Stihl product in the plastic bottle. Went fine, smelt funny but if you aren't in the center of a town it's just a pain in the arse to get for us semi and fully rural dwelling types. Plus there's a heap of bottles to dispose of, they don't do refills by the 20L!

As far as the original question, which 50-60cc saw - I've been asked that twice in the last week by people looking to upgrade a little battery saw as they end up spending too much time on smoko break waiting for recharges! Battery saws are very good, but the downside is by the time you buy three batteries (one charging, one ready to go, one in the saw) the price is a little ouch.

Have noticed the dye colour fading in older fuel but it is usually very old fuel so petrol has gone of anyway. We don’t take any risk. Dump fuel, at a cost of $3+ per litre, and refill with fresh stuff. We have to be mindful that it doesn’t take too much w/shop time for repair cost to be worth more than saw is worth in some cases.
If the fuel has been mixed for a month use it in your lawn mower, safer that way especially for the bigger saws. I know people use older fuel but personally I replace after about a month on my 4x saws. I hate the prospect of working on my own gear unnecessarily.

Interesting to note that running your mix too oily can result in hotter internal temps too. This video uses a reasonably drastic example of 25:1 (compared to 50:1), so a much more exaggerated outcome than say 40 or 45 to 1, but still shows there definitely can be such a thing as too much oil, especially if running under heavy load over the longterm.

https://www.youtube.com/watch?v=9ywMl30_JPI
(Skip to 13ish minutes if you just want the results)

Yep, oil has a higher calorific value than petrol (i.e. produces more heat when it burns). The density of the fuel makes a marginal difference to carb fuel metering, as does but to a lesser extent things like altitude and to a greater amount air and engine temps. The actual amount of oil in the mix is one of the lesser factors, by that I mean the difference between 50:1 and 40:1 ratios is less than one percent change in the brew. That doesn't really equate to anything weird for engine running, and as another example leaving a can of fuel in the sun to heat up and using it hot produces more of a density difference when compared to running the same fuel on a cold morning with the can temperature as low as you'd get.

Originally Posted by woods223

Have noticed the dye colour fading in older fuel but it is usually very old fuel so petrol has gone of anyway. We don’t take any risk. Dump fuel, at a cost of $3+ per litre, and refill with fresh stuff. We have to be mindful that it doesn’t take too much w/shop time for repair cost to be worth more than saw is worth in some cases.
If the fuel has been mixed for a month use it in your lawn mower, safer that way especially for the bigger saws. I know people use older fuel but personally I replace after about a month on my 4x saws. I hate the prospect of working on my own gear unnecessarily.

Yeah, I chuck it through the ride on mower blended out with straight fuel to get the oil amount down. The mower doesn't seem to mind even older fuel like that, worth noting though that most good two stroke oils contain a stabiliser component nowadays and if you are using 98 or 96 (non-ethanol) grades to start with the fuel should stay usable for a lot longer than a month before it goes pear shaped on you. I swap out the fire brigade stuff every 6 months or so and so far this has completely ended all of the stale fuel issues that we historically had.

i chuck mine in the car..but will admit its got to be pretty old before wont use it..normally its been used up in lawn mower well before it goes funny...

Chainsaws etc generally aren’t as as highly tuned racing two stroke motors. Difference of less than 50 metres altitude and cold morning vs warmer air later in morning can lead to engine seizure coldie to leaning mixture. Fuel injected chainsaws are a little temperamental regarding this and rainy versus fine day. A few saws locally need to be put through tuning cycle regularly to get good day to day running. Pruning gangs seem to notice this more.