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Hi, newbie to boating, I have gone through about 10 tanks, around 150 gallons of fuel and am wondering if my assumption about mixing is correct. My outboard is a 1992 Evinrude 90 with the VRO disconnected. Have been using 50:1 ratio. Basically, when tank is at 1/4 or so, I trailer to gas station, fill the tank with best grade available to almost full, then add oil at 50:1 ratio at end. Tank is a Moeller 22 gallon above deck. My drive from the gas station to the ramp is about 1 mile with numerous stop signs and turns. Up until now I have figured that this would be enough motion to properly mix the oil and gas. Upon start up, motor always smokes, some days a bit more than others, using Evinrude 30 oil. At idle on the water once warm, there is a faint smoke as well, so to me this would appear normal. The other day, while cruising at 30mph, the motor made a constant higher pitch sound, kind of like prop aerating, but prop was fine in water. No loss of power or strange idling though. Suddenly got me thinking could this be because my reasoning behind oil and gas mixing is not correct and am possibly damaging engine by running lean. Besides premixing fuel at home in smaller containers through vigorous shaking, does this seem like an acceptable way to proceed? How are others with similar size tanks generally doing the mixing?
It is very unlikely that you are lean. Usually when premix is done, the oil buildup in the tank leads to richer and richer mixture over time. My guess is that your sound is something else. My personal recommendation, however is that you repair your automixture. The carbon buildup inside of engines that have been converted to premix is usually terrible. My alternative recommendation is that you use mercury powertune occasionally.
Lucas M wrote:... Basically, when tank is at 1/4 or so, I trailer to gas station, fill the tank with best grade available to almost full, then add oil at 50:1 ratio at end. Tank is a Moeller 22 gallon above deck. My drive from the gas station to the ramp is about 1 mile with numerous stop signs and turns. Up until now I have figured that this would be enough motion to properly mix the oil and gas. ...
Two problems with your method:
1) You should add the oil prior to filling the tank, to ensure complete mixing, by estimating the amount of fuel you will be adding to the tank.
2) It is not clear from your description whether you are adding a 50:1 oil ratio based on the size of the tank or based on the amount of fuel you added to the tank? If the former, you will end up with more oil in the mixture than necessary.
Hi, I am actually using 50:1 based on the amount of fuel (2% of gallons). The reason I started doing the oil after the gas is because one time I went to Marina station and told attendant 50 litres of fuel please because I had put in my 2% before, he pumped it, told me it was good, and off I went. Boat smoked a lot. When I got home I looked at the invoice and noticed he put $50 rather than 50l which then turned out to be only about 30 litres. So I ran way to rich. Decided from then on to eliminate the middle man and do it myself but with known quantity of fuel to avoid the back and forth mixing.
If you really want to eliminate the "middle man," connect the Oil Management System (OMS) system, aka Variable Ratio Oiling (VRO), and let the pump determine the correct ratio of oil to fuel. The OMS pump varies the ratio dependent upon engine rpm's, which is preferable to a standard 50:1 mix. If you want to reduce or eliminate exhaust smoke in your 1992 E90 cross-flow, then use a synthetic or synthetic blend tcw-3 two stroke oil, e.g., Evinrude/Johnson XD50 oil. the conventional practice is to add the two stroke oil to your tank prior to adding gasoline. When was the last time the outboard was treated using BRP Evinrude/Johnson engine tuner? See details of product in link: https://www.amazon.com/Johnson-Evinru...B001KYJAL0
Thanks, the engine tuner is on order was planning on doing it in the fall, might do it before just to see result. I have been using the Evinrude 30 oil and there is very little smoke so i am happy with that performance (although I have to drive 30 miles to the dealer to get it, Walmart 5 min away and has some Castrol TC3 oil...). The VRO tank has been removed and at this point it might be more complicated to put it back than to premix and run the engine tuner from time to time. Previous owner had boat 8 years and had VRO disconnected the whole time and so did owner before him. So if I understand correctly the reason for putting oil first is that pumping the gas after mixes it well (as opposed to gentle shaking from trailering).
Lucas M wrote:
.... So if I understand correctly the reason for putting oil first is that pumping the gas after mixes it well (as opposed to gentle shaking from trailering).
Correct.
Since you are filling it at a street-side gas station, you should be able to control the amounts of added fuel and oil yourself. I would not expect a 1-mile drive from the gas station to the ramp to adequately mix the oil in the fuel.
Add the oil first, and adding too much isn't that much of a problem, its when you add too little that you run into issues. Most older two strokes call for 25:1 for the first tank of the season to really lubricate all moving parts after sitting for a winter.
You could try running some seafoam through your fuel system, I found after a couple of hot soaks overnight and running it out the next day on the water I idle better and everything sounds smooth. Just one data point on a different model though.
rockinhitz34 wrote:
Add the oil first, and adding too much isn't that much of a problem, its when you add too little that you run into issues. Most older two strokes call for 25:1 for the first tank of the season to really lubricate all moving parts after sitting for a winter.
You could try running some seafoam through your fuel system, I found after a couple of hot soaks overnight and running it out the next day on the water I idle better and everything sounds smooth. Just one data point on a different model though.
Good luck!
Professional Techs will advise you not to overmix. The 50:1 ratio requirement is for full throttle. Otherwise it is always running rich. This results in carbon buildup and can make your piston rings stick and loss of compression results. Ideally, the factory oil injection is really better for the engine. When premixing, two great products are Quicklean, and about once a year a Powertune to dicarbon your engine.
Also, the additive Techron is the same formula as Quicklean, and buying fuel at Chevron gets it to you for free. It will help if you are dead set on premixing. Just be prepared for occasionally fouling plugs is you don't run wide open, and if you lose compression, Using quicksilver powertune will work wonders for decarboning.
I've been running 50:1 premix for about 50 years now. That has never caused a problem, even for kickers that run 5-6 hours at a time trolling. I do, however, run Ringfree in each tank.
At worst, they may smoke a bit on startup, and again when I goose the throttle after trolling, but never in between.
After 50 years experience with OBs I wouldn't be caught dead with a VRO system. That would be the first thing I would disconnect. I have had marine engines with that system, as well as old motorcycles, and all have been problematic. Huge smoking or engine grenading because of too much or to little oil. I'm sure they work just fine now, but not in MY boathouse.
My gas tanks are calibrated - I did it myself. A simple view and i know how much fuel needs to be added. Oil first, then pump in the calibrated amount of gas. Easy, peasy.
These days in my old age, driving the boat to the gas station is also too much of a hassle. I make the premix in three 5 gallon gas cans (4.5 gal per can) and then use the cans to fill the boat in the garage. Easier peasier......LOL.
Thanks for all the feedback. i just hope now that I did not damage engine because of putting oil in last for those 10 tanks. It would be a shame to have an engine running great for over 25yrs to have it die off for a stupid reason...I love the sound it makes on startup and idle, really do not want to put a new engine on there.
