Is it better to nix higher or lower than 50:1?

I've just read a nice thread on 100:1 vs. 50:1, which got me thinking.... (dangerous to be sure).<br /><br />When mixing gas and oil, should I mix on the oil on the lean side (more of a 60 to 1 mix) or on the safe side (more of a 40 to 1 mix), or does it matter? Will I see any performance issues either way? <br /><br />It may be a stupid question, but I'm just an inch shy of stupid (when it comes to boat motors..). Thanks.

Re: Is it better to nix higher or lower than 50:1?

What engine? If your motor requires 50:1 -- mix at 50:1. If it was ok to mix at 60:1 the engine manufacturer would specify that ratio. If you must err -- err on the heavy side (more oil).

Re: Is it better to nix higher or lower than 50:1?

Sorry about that.. it is a 50 to 1 mix (Evinrude 48 SPL). I'm having some idle problems with the engine, so I was wondering if adding a little extra gas would help. <br /><br />In addition, sorry about the double post. Hopefully a moderator will fix it for me!

Re: Is it better to nix higher or lower than 50:1?

Why would you want to fool around with the ratio? If you do go rich on the oil, remember too much & you start to have smoke & carbon build up problems, Too lean & you may do real damage to the motor. As stated by Upinsmoke, stick to the ratio the engine calls for.

Re: Is it better to nix higher or lower than 50:1?

if you were to make a mixing error, youd rather have a bit too much than not enough.

Re: Is it better to nix higher or lower than 50:1?

I agree with the above advice. Do what the maker advises.<br /><br />If you must experiment, go with more oil, but you will gain nothing but more smoke and more risk of fouled plugs.<br /><br />Most 50:1 engines will survive leaner mixtures, but NOT ALL. There will be no performance gain.<br /><br />Trust the maker. They really do know what they are doing. . . and we don't.

Re: Is it better to nix higher or lower than 50:1?

Ive actually argued against what Im going to say, but mostly just to give ZMOZ a hard time, but here goes.<br /><br />If you are using an oil which is a 50:1 TC-W3 oil, in an engine that requires a 50:1 mix ratio, and you are running the engine at WOT more than at an Idle, you can actually gain a bit of HP with a little more oil, say 40:1, This would only show on a dyno though, and may or may not show in the seat of your pants. This is pretty evedent in the 2 stroke motorcycles, not so much in outboards. In your case, not worth the trouble.

Re: Is it better to nix higher or lower than 50:1?

less oil - probably get a bit more power but then you'll toast your engine..<br />more oil - you'll have a 'well oiled machine'..so much so that it may bog down and quit, at the best it will blow gunk and smoke all over the place..<br /><br />why even dabble..<br /><br />if you have already done this accidently, and errored on the side of lean (less oil) and smelled a charing smell..then you may have carbonized some pieces parts... you may want to run it as advised..but DONT run it super oily as this sudden change may affect the engine negatively...<br /><br />if boat engines are anything like RC engines that is <br /><br />S

Re: Is it better to nix higher or lower than 50:1?

Frankly, it is my belief (an opinion, nothing more) that the 50:1 ratio is arbitrary, but also probably within a range that the manufacturers have found acceptable through testing. They recommend 50:1 because it is a very convenient measuring quantity in the US: 1/2 qt(1 pt) oil to 6 gal. fuel, (of course it works well with metric - but any ratio would be easier in Metric, no?)<br /><br />You really think that a research-based optimal oil level just happens to coincide with using a US pint of oil? Maybe I'm FOS and they specifically design their engines for that precise ratio, but I still think there's a range.<br /><br />They don't recommend a range for mixing because that would be more confusing to the average user.<br /><br />My guess is that 40:1 is outside that optimal "range" and wasteful or maybe even harmful (I doubt it) because if it were within the range, they'd recommend 1 pt for 5 gal. Sell more oil. 5 gallons is a more "round" and common amount also (all hand carried tanks in US are 5 gallons).<br /><br />We've seen them toy with leaner ratios now and then, I therefore think their research has shown a safe fudge factor leaner than 50:1, but not a strong enough factor to break with the long standing tradition or change to something that would require a whole new universe of, say, 7 or 8 gallon tanks (which would be too heavy for a lot of folks anyway). <br /><br />Therefore, again an opinion only, I think it's likely 50:1 is no magic number but an easy measurement within the acceptable range. <br /><br />I premix in a 24 gal on-board tank. When topping off, I never measure oil more precisely than whole pints and mix according to whatever the actual fuel amount is rounded up or down to the nearest 6 gal increment. I do bias my rounding towards the rich side though, but occasionally it's a tiny bit leaner than 50:1 for a tank top-off. The minor and probably totally acceptable error is virtually nothing when mixed with existing fuel in tank. When filling an empty tank, it comes out right at 24 gal or very close to that, so there's no rounding error.<br /><br />Just staying up too late babbling.

Re: Is it better to nix higher or lower than 50:1?

I've been running 100-1 premix on top of my oil injection {11 year old merc} as an insurance policy so to speak.<br />I changed the oil lines this year but havent gotten around to pulling plastic drive gear for inspection which are somewhat prone to faluire..<br />I buy castrol oil @ 9 bucks a gallon, very little smoke & still cheaper then running Yamalube or Merc oil @ 50 to 1 .<br />I've allready done 1 powertune this season @ 25 hours, engine's running like a sewing machine.<br />I dont believe it's a bad thing & if you consider the oil injection leans it out to something like 200-1 or leaner @ idle & low RPM's so I may still be burning less oil the someone who pre mixes 50-1 exclusivly & @ the higher RPM's & WOT it's got to be better for the engine to be getting a little extra oil.<br />I wouldnt be suprised that an engine run this way will outlast a 50-1 engine.<br />You got to figure some performance Merc engines are run @ 40-1 & they make more HP that way & blow up less often .<br />But I do admit if it was a new engine under the warranty I would stick with the oil injection exclusivly & no pre mix so it's an insurance thing for me mostly & I'm cheap but I believe it's running better then last year when I didnt add pre mix.<br />Also I dont buy into everything the manufacturer says, open most automobile owners manuals & they suggest oil changes every 7500 miles & oil filter changes every other oil change.. <br />Allmost forgot, my answer to Kevin's question is higher

Re: Is it better to nix higher or lower than 50:1?

Scali -- read your auto owners manual again and check the fine print. Bet it says cut the oil change interval in half under severe service. In most parts of the country, short trips, cold weather, towing, dust, and heat all amount to severe service. As for outboard race motors -- they are rebuilt on a regular basis and therefore calculated risks are taken with clearances, oiling, fuel delivery and a host of other things that can't be considered for longevity on a recreational outboard.

Re: Is it better to nix higher or lower than 50:1?

Good point upinsmoke & you just reminded me I need to change the oil in my truck because i'm trailering these days.<br />But even if I drive @ 55 MPH's in 50 degree weather my oil & filter gets changed @ 3k.<br />If you check oil an analysis @ 3k miles most show a breakdown in additives, moly ect. <br />I believe theres a certain train of thought in the automakers that they want your car to wear out every 100k miles or so because they can sell you a new one & make more money. <br />But my point with my post is I'd be willing to bet that running say 40- 1 is better for these 2 strokes..<br />I can really tell the difference in smoothness with my engine, OK maybe I carboned the crap out of it, LOL ..<br />It's a gut feeling I guess, & I'm talking just a little extra oil ..

Re: Is it better to nix higher or lower than 50:1?

This has been an on-going debate since they got away from 30 weight car oil and went to two stroke water cooled specific oil (TC-W). <br /><br />Heres just some of the ideas you'll hear;<br /><br />More oil takes up more space in the calibration passages of the carbs so it actually is leaner on fuel.<br /><br />The skirt to wall clearance for any given engine is set around cooling properties and the thickness of the oil in that space. Too much oil can actually become a heat insulator instead of transfering heat from the piston to the walls.<br /><br />More oil creates more power from higher combustion (I'm sure that one came from the deal about squirting oil in the cylinder just before the customer does a compression test).<br /><br />More oil creates less power because it doesn't burn like gas.<br /><br />Now I dont necessairaly buy into any of these ideas but it just shows how the debate can go on & on & on...........<br /><br />Well, heres what we did with a couple of the race boats. One was a V4 and one was a V6, both OMC big bore loopers. Both stock (class rules) except for higher compression heads and different flywheels.<br /><br />On 50:1 Evinrude TCW 2 (and later TCW3) oil or Pennzoil partial synthetic the V4 turned 8200 and the V6 turned 8800 in the 1/4 mile. <br /><br />We ran 40:1 and the rpm was the same, the ET was the same.<br /><br />We went to full synthetic at 100:1. The rpm was the same, the ET was the same on both. (Took a bit more out of the budget!) Yes, the discoloring on the bearings was way less leading us to believe the heat transfer was better. But we had no bearing failures with TCW2 or 3.<br /><br />I do believe that running too much oil can eventually lead to faster coking. One tank isnt going to do it though. I also believe that too little oil can lead to problems but it'd have to be a lot less oil.<br /><br />And so it continues...........