Oil for 2 stroke outboards?

M

MacMan

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Hi all,

I've just brought a new outboard - a Mercury 3.5 Hp two stoke.

Reading the manual gives dire warnings of only using NMMA certified Mercury Tc-W3 2 Cycle oil at 25:1 for the first tank

Now how much of this is marketing and how much will any old oil do the job ?

In particular I am landlocked (Berkshire) and nowhere near a swindelery and wondered if there is something I can pick up at Halfords to do the job ?

Cheers

MacMan
 
I think you'll find any old 2-stroke oil will work. I don't know if "marine" 2c oils have anything special in them, tho' I think it would be gilding the lily if they did, but don't use "any old oil", especially if it's old sump oil!
 
You might do well to find a shop selling garden machinery, chainsaws etc, they should help. Have a look and see what the spec is on the container.
 
Have a look at www.rockoil.co.uk
No You don't need "Mercury" oil.
Yes make sure the spec is Tc-W3 2 cycle.
Brand does not matter.
Use the ratios the manual gives You.
Don't be tempted to put "A little more in" once You have run it in, in effect.
Too much oil can also give problems and damage believe it or not.

People might comment that they have used Lawnmower oil, etc and have experienced no probs. Don't be tempted to go down the route of any old 2 stroke oil will do.
Especially as You have a nice new one!
Rock oil, mentioned above are a "Brewer" of oil and produce for lots of well known brand names, so You can buy the same stuff without buying the brand name.
They will be able to tell You who stocks it near to You.
Got no commercial connection, just used their oils for various engines for Years.
Oh and make sure the tin says "Premix" not "injection"
 
because they are water cooled they tend to run a bit cooler so they probably have more additives to prevent "whiskering" of the plugs etc. but I cannot see any harm by using any good quality 2-stoke oil. I use 2 stroke motor bike oil and havent had any probs.
 
Oil for strokes is apparently formulated for running at cooler temperatures than that for air cooled and closed circuit cooling 2 strokes. So I am led to believe.
Can't think it would make a whole load of difference unless you ran it hard before warmed up.
 
Good point, I used to use the cheapest oil on my old 2-stroke bike (KH250) because the oil pump would throw so much oil into the mix that the expensive stuff (i.e. Rock oil) was a waste. It all dripped out through the exhaust, unburnt, anyway. With a new engine and a thinner mix, good oil is not such a bad idea.
 
That was cos the oil pump setting was incorrect!
The KH range was touchy ref carb/oil pump cable settings.
Uknowledgeable dealers of the day would uncrate a machine stick fuel and oil in and whisk em out the door.
If it fired up and went round the block without stalling. That was a Pre Delivery Inspection over.
Must have "tuned" dozens of the buggers back then.
Wrong settings, even wrong plugs.
Peeps who thought the bikes would go better with"softer" plugs.
Cos they were oiling up they'd stick the wrong grade in and have nice holes in the pistons instead!
Twas good fun!
 
/forums/images/graemlins/smile.gif Oh well, it's too late now. What I remember well was steaming off down the A3 trailing a haze of blue smoke, Volvo drivers coughiong and spluttering in in my wake. /forums/images/graemlins/smile.gif
 
I took the perceived wisdom of cooler running watercooled two strokes seriously and to date have only used Quicksilver stuff from a swindlery.

However, FWIW my local car accessory shop (not Halfords) stocked three grades of Comma oil, mineral,semi-synthetic, and fully synthetic. This last one may indeed be suitable for outboards. The packaging is silent on the subject. One litre was about £7 and 4 litres of the real McCoy was £16. So no real contest.

Even though you're landlocked what about the Inland Waterways, Midland Chandlers at Braunston, chandleries on rivers in your area?
 
[ QUOTE ]
Oil for strokes is apparently formulated for running at cooler temperatures than that for air cooled and closed circuit cooling 2 strokes. So I am led to believe.

[/ QUOTE ] many years ago I did look at water cooled outboard oil and air cooled motor cyle oil in the lab. I cannot remember any figures now or the brands, but i found that the oil for the air cooled engines had a significantly higher viscosity. I belive not only does the have some direct bearing on the lubrication but will also may affect the fuel air ratios.

If it says an oil to a TC-W spec then that is what should be used
 
Your right again Vic, it will affect the the fuel air ratio. Which is important.
Ok Guys. Yes use any old oil. The motor Will run, presumably OK.
Long term however probs Will arrive.
Do You want--whiskering plugs, rings gumming up and sticking to the piston ?
Unreliable starting, smoke, noise ,smell. Lack of power etc etc.
Damage to the cylinder, I could go on.
For the amount of usage a little outboard gets the oil price is a none starter really.
Think about this. One small 2 stroke water cooled engine. Used in relatively small bursts. Different usage to Your Lawnmower, Moped, Motorcycle, Chain Saw,Leaf Blower,de dah de dah de dah.
Dormant for long periods, then is woken up and expected to perform.
The little buggers have a hard life in this respect.
So Manufacturers/Blenders do take note of this phenonemon, believe Me I've worked with them.
Could go on and on about this subject but will become boring and serious.
That will not do! /forums/images/graemlins/smile.gif
So stick the correct stuff in it Does make a difference. /forums/images/graemlins/wink.gif
 
Please can you (or VicS) explain WHY type of oil (or indeed the petrol/oil ratio) has an effect on the fuel-air ratio?

Reason I ask is currently investigating a 2-stroke genny with starting difficulties and everything points to carbureter (and in particular slow running mixture jet has negligible effect). Previous fuel mix unknown, though have topped-up with new petrol/air-cooled 2T oil. (OK, should have drained all the old stuff out first!)

Vic (M)
 
If the mix is too oily or not oily enough.
This applies to premix two strokes only by the way.
The "balance" of air, oil ,fuel is upset.
Sorry triying to explain with My limited typing skills and "on air" vocabullary is difficult.
Especially after a wine or two!
I drink the stuff and She wines at Me!
Tiss a mixture thing again!
Starting prob.
The critical dose of oil won't initially create a starting prob.
"The slow running jet has negligable effect".
Don't know what genny You have. However, "slow running jet" Do you mean the srew You adjust to affect the tickover or the "pilot air srew" which usually affects the mixture up to about a quarter throttle?
If the eng has starting probs the settings for said pilot jet in most cases are--- Screw it in till it is "home" then unscrew for a turn and a half.
Thats the pilot jet sorted for now.
The tickover screw is normally adjusted by screwing "in" to increase tickover speed and screwing "out"to decrease.
What happens if too much oil is added to a pre mix two stroke is as follows.
There are 3 elements to consider.
Petrol air and oil. No air no explosion, no fuel no explosion, no lube no lubrication no go eng seizes.
Cos the 3 have to be in a balanced quantity too much of one will upset tother.
The basic Carb normally sorts this out.
Shove too much oil in and yer basic carb can't cope. What the carb does is"atomise" the correct fuel air oil mix into the combustion chamber by way of help from the piston and ports.
The correct air fuel is needed to make the bang. If too much oil is present it can weeken the fuel air mix. If the mix is too lean, combustion is parred and so is lube.
I could go on and on but believe Me it get's boring.
If You've got starting and slow running probs with a liitle 2 stroke be it a genny or whatever. Sometimes it points to a duff crancase seal on the timing side. Specially if the slow running adjustement seems to have no affect.
What happens is there is a loss of crancase pressure and no amount of fiddling with slow running settings will cure this. Air is sucked in through the duff seal and she won't idle or start too easily. Any amount of slow running jet adjustement is futile.
Has the eng stood for some time?
Always go back to basics.
Take the plug out. Check the spark.
Drain the carb/float bowl.
Check the tank can breathe.
If she don't fire after three pulls summats up!
Choke setting/throttle setting/fuel on etc etc.
Old fuel, especially with pre mix two strokes isn't nornmally the prob ref starting.
Consider this. A premix 2 stroke doesn't receive "pure petrol" it's by nature already contaminated by oil.
So they are not fussy high tuned gadgets that need 100% high octane supuer juice.
Especially at our level of outboards and gennys etc.
Clean fuel and oil Yes but not F1 technology. Water is a nuisance we don't want that in the float bowl.
So we need a good spark, at the right time some clean fuel(with a bit of oil in) some air to ignight and ther You go simps innit.
Type of oil has little affect on air oil ratio or petrol oil ratio. Amount does.
Soory not to be more clear but it is 23.00 hours!
 
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