oil mix ratio for "High Performance"

[outlaw 10.5]

Guys,
I was looking through my OMC manual and noticed it said " for High Performance Use" without VRO , mix oil ratio to 25:1.
Has anyone else done this ? What do you High Performance OMC guys do? I have a pair of 2000 225 HO carb motors, Monty heads with about 130 # compression and 93 octane fuel.

Thanks
Tim

[jwall116]

I was wondering that myself. I have a bone stock OMC 130 Looper, and pre-mix at 50:1

[FMP]

Somewhere in the wealth of information on this site is a test that shows you make more power with a bit more oil. If you run it hard and spin it you might as well be covered with a bit more film to reduce the friction and protect. Its an old test but still applies even with today's " better oils" , so why take the chance. I looked at a neighbours late model 15 Johnson two stroke the other day and noticed the sticker 100:1 , I said why?

[outlaw 10.5]

No one can tell me what they mix for High Performance use. I know it may be mixed opinions but someone could chime in. I'm just curious because I have always mixed 50:1 but would mix 40:1 or 32:1 if that would be better for longevity.

[FMP]

So if its continuous 6000+ use 40:1 at least and 32:1 if you're really turning it and want to be safe.

[Robby321]

So if its continuous 6000+ use 40:1 at least and 32:1 if you're really turning it and want to be safe.

I totally agree..

[flabum1017]

Normal use is fine with whatever the manufacturer suggests..... A lot of the Lemmonrudes went to 100:1 in the eighties. Personally, I like 50:1 for fish/stock motors and 40:1 to 32:1 for hard running, high rpm motors...... I'd rather replace plugs than pistons and bearings

[FORBESAUTO]

:iagree:With above post. I run 40:1 up to 6500 and 32:1 above that. 50: 1 stock. I experience motors seem to make more power with richer oil mixtures. But be aware that the richer oil mixture can lean it a tad and may need to richin up slightly to compensate.

[Mark75H]

Was at a race about 5 years ago pitted next to Fred Hauenstein (former high up engineer at both Merc and OMC ... and long time second generation boat racer)

Watched him mix his own oil ... 25:1

[FMP]

Oil her up:thumbsup:

[outlaw 10.5]

Thanks for the replies guys, I just mixed it 40:1 , motors turn 6300 with current set up and don't run there that often , mostly cruise about 4500 or so.

[olboatman]

I also agree that the higher you spin a two-stroke the more oil needed. I do not think that 100 to 1 is exceptable over 1000 rpm!!! JMO Gary

[flabum1017]

I also agree that the higher you spin a two-stroke the more oil needed. I do not think that 100 to 1 is exceptable over 1000 rpm!!! JMO Gary


Oil has vastly improved from the old days Oldboatman :D.

[Umassot50]

The only time "newer better" oils are any better is when you get down to the bare minimum acceptable oil level for your engine. The slightly better film strength and higher flash point will protect better when your at the absolute minimum oil level. Add a little more oil and it's a wash. More oil is better for more power and protects engines from wear. Two strokes love oil. Dont deprive them.

[Bodhi]

In this case follow the promax's. .....32:1. If it ain't smokin....it's gonna be broken

[Krazymaan]

My 1984 Oval Port Mod VP is suppose to be between 18 to 1 and 25 to 1 With Aviation only fuel.

[powerabout]

there is a dyno test of a bike engine where they got to 16:1 oil ratio and it kept making more power the only reason they stopped there was they couldnt jet it any larger as it was getting leaner and leaner as you replace fuel with oil.

[olboatman]

My 1984 Oval Port Mod VP is suppose to be between 18 to 1 and 25 to 1 With Aviation only fuel.

I think this statement sums it up....Merc does NOT want oil to be a problem( or lack of it) in their Hi-Po motors. They must know something!!!:rolleyes::smiletest: Gary

[outlaw 10.5]

Do I need to jet up to run 40:1 ratio? It was jetted perfect for 50:1.

[FMP]

Factory jetting is over safe so we hope . Run it and check but I would say probably not.

[powerabout]

Omc are happy to run 25:1 with stock jetting

[ChrisCarsonMarine]

Normal use is fine with whatever the manufacturer suggests..... A lot of the Lemmonrudes went to 100:1 in the eighties. Personally, I like 50:1 for fish/stock motors and 40:1 to 32:1 for hard running, high rpm motors...... I'd rather replace plugs than pistons and bearingsYou're completely correct,and the only reason the small omc's went with 100:1 was to get them to pass emissions tests,and they couldn't afford the cost and space to incorporate the VeryReluctantOiler.Yes the quality of the newer oil is better,but we didn't turn our motors as hard then either,Chris

[Mark75H]

I did some scientific flow testing with ratios from pure gas and 50:1 down to 16:1. I could not measure any flow decrease until the ratio was below 20:1. The restriction was much greater than a carb jet, so the results were amplifed toward the cautious side.

I can say the answer is DEFINTELY no jet change requirement in the range that would actually be used.

The next thing people freak out about is possible octane rating suppression. Convert the ratio to percent (50:1 = 2% ... 25:1 = 4% ... 20:1 = 5%, etc) ... you'll get over the octane suppression fear even if the oil's octane was ZERO, which it is NOT.

[flabum1017]

The next thing people freak out about is possible octane rating suppression. Convert the ratio to percent (50:1 = 2% ... 25:1 = 4% ... 20:1 = 5%, etc) ... you'll get over the octane suppression fear even if the oil's octane was ZERO, which it is NOT.

oil burns slow, that's why there's smoke. if it burned as fast and completely as the gas, there would be no smoke and octane would be a concern.

[pointer]

^ In my testing of RC boat engines, 20:1 was optimal. Totally different application but same determination.
More oil didn't produce any measurable on the water increase in performance.
Less oil has less performance.
This was 25cc single water cooled spinning ~ 12500 RPM. Tiny tach and onboard GPS, recorded results, prop switches to load engine more and also to load engine less. I liked Klotz Super Techniplate at the time - 15 or so years ago.

pointer

[olboatman]

This thread is becomming very interesting...... I have aways believed the how 2 stroke oil is used is far more important than the brand or type as long as it is high quality and has the proper rating (TC-W3 etc.) As far as rejetting I have never seen a problem using more oil as long as the jetting wasn't already on the edge. I remember using Chemlube (one of the first 2 stroke synthetics) back in the early 70s in my sled at 7k plus rpm at 25 to 1 with no problems or plug issues even with stone age ignitions.

[FMP]

I used to think a bit less like 60:1 was good enough with todays oils. Now I still use a very good syn oil but find 40-45:1 gives me peace of mind when turning 6000+. ONly the cowl is 105.

[King Dad]

I remember in the late 80's or..... whenever it was, .... when OMC went to 100/1 on small two strokes. 35 hp and down, I believe.Supposedly, according to the service clinic notes I received, they "silver coated" the main bearings to help with heat dissipation and the leaner mixture. I worked at a very large Johnson dealership then and all our white engines had much, too much black exhaust residue from 50/1. We also sold Yamahas and they didn't have that issue due to 1) grey color vs. white and 2) they already were pre-mixed leaner. OMC said unless you ran for prolonged times at WOT, 100/1 would be fine for 90%of the people out there. I can't say I had any running issues with customers running at 100/1 but we had a zillion powerheads fail in the spring. Alot of customers didn't "fogg" their motors in the fall and the leaner oil residue wasn't enough to protect rod bearings over the high humidity winter storage, which is what we had in the Puget Sound region. 1st or 2nd time out in spring the engine would seize. OMC went back to 50/1 after a few years of 100/1. Another failed attempt to beat the Japanese....... Sad!
We had a few fishermen I called "professional fishermen" as they were retired and lived on the water day in and day out. They caught so much fish I swear they depleted the winter salmon runs each year. Those guys could wear out a set of rings faster than anyone we knew. We told them they would have to stay at 50/1 as we were'nt gonna keep repairing their engines for free. By then Yamaha and Suzuki had oil tanks mounted on their engines and OMC came out with Auto-Blend tanks... Still sad!! .

[powerabout]

I did some scientific flow testing with ratios from pure gas and 50:1 down to 16:1. I could not measure any flow decrease until the ratio was below 20:1. The restriction was much greater than a carb jet, so the results were amplifed toward the cautious side.

I can say the answer is DEFINTELY no jet change requirement in the range that would actually be used.

The next thing people freak out about is possible octane rating suppression. Convert the ratio to percent (50:1 = 2% ... 25:1 = 4% ... 20:1 = 5%, etc) ... you'll get over the octane suppression fear even if the oil's octane was ZERO, which it is NOT.
this was a viscosity test
How about when oil replaces 5% of the fuel can we assume that all the oils have a different octane rating and burn differently so some oils might lean it out more than others?

[Mark75H]

this was a viscosity test
How about when oil replaces 5% of the fuel can we assume that all the oils have a different octane rating and burn differently so some oils might lean it out more than others?

5%? who is running 20:1 and having trouble? Merc ran the T2's there with no problem.

Its just not related. Fuel ratio to air is fuel ratio to air, whether the fuel is gasoline or tar.

Compounded by ... the tiny amout of oil involved. I challenge anyone to see a 2% change in mixture strength without a pyrometer or O2 sensor ... and even then I'd put the chances at 50/50 accuracy at 2% change. And as I said, the oil is not zero on any scale. AND this theoretical 2% mixture strength change would depend on the oil being 100% non combustable; this is not the case either.

If the octane rating of the oil was zero, the maximum octane change of changing from 50:1 to 25:1 would be slightly more than 2 numbers. Some synthetic oils actually claim to be (and probably are) octane increasers rather than neutral or decrease. Oil is not zero octane, so there is NOT a 2 number drop in the rating of a stronger oil mixture.

[Robby321]

This thread is becomming very interesting...... I have aways believed the how 2 stroke oil is used is far more important than the brand or type as long as it is high quality and has the proper rating (TC-W3 etc.) As far as rejetting I have never seen a problem using more oil as long as the jetting wasn't already on the edge. I remember using Chemlube (one of the first 2 stroke synthetics) back in the early 70s in my sled at 7k plus rpm at 25 to 1 with no problems or plug issues even with stone age ignitions.

Yep been there, done that! Don't think I ever ran anything 2s more that 40-1 and never a prob! Never forget.."more oil is better than less oil"!

[Robby321]

5%? who is running 20:1 and having trouble? Merc ran the T2's there with no problem.

Its just not related. Fuel ratio to air is fuel ratio to air, whether the fuel is gasoline or tar.

Compounded by ... the tiny amout of oil involved. I challenge anyone to see a 2% change in mixture strength without a pyrometer or O2 sensor ... and even then I'd put the chances at 50/50 accuracy at 2% change. And as I said, the oil is not zero on any scale. AND this theoretical 2% mixture strength change would depend on the oil being 100% non combustable; this is not the case either.

If the octane rating of the oil was zero, the maximum octane change of changing from 50:1 to 25:1 would be slightly more than 2 numbers. Some synthetic oils actually claim to be (and probably are) octane increasers rather than neutral or decrease. Oil is not zero octane, so there is NOT a 2 number drop in the rating of a stronger oil mixture.

Spot on Sam, spot on!

[powerabout]

I wonder if a diesel will run on tcw

[Robby321]

i wonder if a diesel will run on tcw

Sure! Maybe a thin out fri grease?

[pointer]

Plenty of people here running diesels on fry grease, biggest problem is cold weather. That is a whole 'nother topic!

Sam is spot on.

pointer

[Krazymaan]

I have 5 diesels.
1 Sprinter inline 5 cylinder
3 - 7.3 powerstrokes
2 - 6.0 powerstrokes
I live in Minnesota. Its way too risky to play the grease game up here because of winter. Most people that experiment with that crap end up failing and destroying their engines.
In my opinion, the other idiots dump used tranny fluid, power steering fluid and brake fluid in their tanks because you can burn that crap with no mods. I don't like the idea of blowing those fluids out the tailpipe.
Like all motors they run best when left stock. Same goes for diesel boats. its bad enough we blow the exhaust in the water, it would be even worse if we were dumping that other crap into the waters.

[ChrisCarsonMarine]

I have run an F350 diesel Ford over 200,000 miles on filtered vegetable oil with no problems. My truck has a heated nine a gallon fuel tank, heated fuel lines, and a heated filter. Solenoid valves are used to start on diesel and warm up, switch to grease, and switch back to diesel before shut down. This system purges all the fuel lines and motor of any grease before shut down...sorry to sub overt the thread...

[pointer]

Agree Chris, and your in Florida. I'm an hour above Maine. By the end of October the temps dip below freezing, and it only gets colder until February.
The only people I know doing it in winter drive 45+ mins a day, and use a system much like you do.

pointer

[powerabout]

who is going to run tcw in their diesel so we get a test done?

[wolfgangb]

Hi guys,
To "retrack" this thread : I built and raced the motors (Chrysler 4 cyl crossflow and OMC looper 3 cyl) for our European "Marathon" (2 to 6 hour) races in the second half of the sixties, when the new super duper synthetic oils (100 to 1) appeared on the market. Turned out the famous Evinrude XD was the Castrol Synthetic rebranded.
We ran the Chryslers (at the time famous for burnt head gaskets and pistons) and OMC loopers at 23 to 1, and never experienced any problems. Right now, i am building a `98 Force 4 cyl balls to the wall race motor,
and will be using any high perf oil i can lay my hands on, but 23 to 1!
Rgds, Wolfgang (South Africa)

[FMP]

Hey there Wolf
Good thread you've brought back up.
You're going to keep the motor happy no doubt.
Will you mix up a special fuel or are you required to specific use as is?

[roadkill636]

I have a 1939 Eveninrude 3.2hp and the sticker says to mix 1 quart of 30wt motor oil to 1 gallon of gas

[powerabout]

who has tested increasing oil ratio and power output?
There was an old bike engine test years ago, they got power gains down to 16:1 then ran out of jets as it was leaning out.
the calorific value of the oil must be a factor?
and your ring to bore sealing

[stoker2001]

I have a 1939 Eveninrude 3.2hp and the sticker says to mix 1 quart of 30wt motor oil to 1 gallon of gas
4 to 1 ratio..LOL

[Mark75H]

who has tested increasing oil ratio and power output?
There was an old bike engine test years ago, they got power gains down to 16:1 then ran out of jets as it was leaning out.
the calorific value of the oil must be a factor?
and your ring to bore sealing

Calorific value of most lube oils is very close to fuel oil/kerosene. Hard to believe you could lean an engine out by adding lube oil. My guess would be very tall boots were needed. You could certainly start to run into octane demand problems, but I seriously doubt the calorific value claims.

[wolfgangb]

Hey there Wolf
Good thread you've brought back up.
You're going to keep the motor happy no doubt.
Will you mix up a special fuel or are you required to specific use as is?
Half Avgas half 95 Oct pump, 180 pounds cranking - guessing. Have another unmolested head, which i can cut as may be required. Rgds W

[wolfgangb]

Hey there Wolf<br>
Good thread you've brought back up. <br>
You're going to keep the motor happy no doubt. <br>
Will you mix up a special fuel or are you required to specific use as is?<br>Half Avgas half 95 Oct pump, 180 pounds cranking - guessing. Have another unmolested head, which i can cut as may be required. Rgds W<br>
<br>

[PanRonnie]

you have a series of kerosine outboards
https://www.marineenginedigest.com/specialreports/kerosene-outboards.htm
they run 30 to 1 premix at a compresion ratio of 5.00 to 1
don,t think overlubing is a problem! underlubing is
on a fourstroke running a rich mixture can wash the oil film from the cylinder walls
2 strokes don,t have that problem , they can chew away ton,s of fuel without any problem

[powerabout]

What oil ratio will effect ring sealing?
I'm sure that will mean each bore finish to ring surface will seal best at a specific ratio

Hence better seal, more dynamic comp but added oil will lower octane
Hows the power output versus EGT look?

[PanRonnie]

on evinrudes they advised 50 to 1 in the tank on top of the VRO for high performance boating giving you 25 to 1 at wide open
the Mercury drag and champ motors as far as i know only run a single ring so they don,t care as much about sealing as opposed to production motors where fuel economy is more important
added oil will lower octane!? maybe don,t know if you can get a hold of an engineer at shell you probably will get your answer

now kerosine output versus EGT a very good quistion!
I have a mercury 150 fourstroke gearcase laying in florida with scream and fly member Chaz
If you take that of my hands for $ 1300,- dollars i will buy a kerosine outboard, put it on my land and sea dyno so i can properly inform you ;)
Do we have a DEAL!? :cheers:

[powerabout]

on evinrudes they advised 50 to 1 in the tank on top of the VRO for high performance boating giving you 25 to 1 at wide open
the Mercury drag and champ motors as far as i know only run a single ring so they don,t care as much about sealing as opposed to production motors where fuel economy is more important
added oil will lower octane!? maybe don,t know if you can get a hold of an engineer at shell you probably will get your answer

now kerosine output versus EGT a very good quistion!
I have a mercury 150 fourstroke gearcase laying in florida with scream and fly member Chaz
If you take that of my hands for $ 1300,- dollars i will buy a kerosine outboard, put it on my land and sea dyno so i can properly inform you ;)
Do we have a DEAL!? :cheers:
lol
I dont need to ship a gearbox from USA to Singapore at the moment...
How about you just run your V6 from 100:1 down to say 20:1 and check the results re power and egt?

[PanRonnie]

Well after my fiveo injector disaster i am very happy both my engines are finally in good working order
So i will have to delay that experiment for another time:D

[Turtleherder]

This thread sure does have some reach. All corners of the US, Canada, Singapore, South Africa and is Aalsmeer in the Netherlands? Great info to, I might go down to 32 to 1.

[Mark75H]

Octane flattening? the actual difference between 50:1 and 24:1 is 2% vs 4% ... a mere 2% difference. Even if the oil was n-heptane or equivalent, the octane difference between 50:1 and 24:1 is negligible


and oil is not zero octane