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MF6HP engine oil

busumark

New member
we have a tohatsu MF6HP bought

we have a tohatsu MF6HP bought from new one year ago and we have been having trouble with the engine oil from the beginning.The motor is used as an auxiliary and for trolling on a 13.5 ft boat.The oil pressure light lit 3 times in one year. and when we checked the oil level was below the lower mark. And when starting the engine there would be white smoke. on one occasion the mechanic told us there is nothing wrong with the motor because he let it work in a water tank for half an hour an the oil level remained the same and changed the oil. after we used it for 5 hours the oil level went from maximum to minimum and we checked the oil level the day after to be sure that all the oil will be in the sump. went to mechanic again and this time he did pressure test and compression test and said everything is right its impossible that there is an oil leak. We went for a trial run with the mechanic and we asked him did you put the same grade of engine oil we were using. he said yes 15W 40. as we were launching the boat he saw that the motor was tilted in and he told us that you cant use a 4-stroke motor in that position because the oil goes out of the sump and goes in the piston. he told us to always keep the motor in a level position when in use. i dont know if this is true. we tried the motor for 4 hours and the oil level remained good to maximum. but it took 45 minutes for all the oil to go in the sump after we turned off the engine. is this normal? after how much time you can check the oil level after turning off the engine?
 
"It sounds like you don't

"It sounds like you don't have anything wrong with the engine. Any missing oil is more likely due to improper tilting of the engine as is is moved from one boat to another. You have to be very careful with a 4-stroke engine as gravity is the only thing that keeps the engine oil where Tohatsu designed to stay. If you had an actual problem it would remain constant or get worse as a leak cannot come and go.

"but it took 45 minutes for all the oil to go in the sump after we turned off the engine. is this normal?"

I'm not sure what you are asking here. Oil circulates throughout the engine while in use. When the engine stops, as it cools, the oil will fill back into the oil pan. I've never timed the process as the difference in oil level would be minute. Therefore, the time interval is not critical in that way. However, due to the increased volume of oil to due raised temperature, you should always check the oil when cold. That will vary depending on environmental factors such as air temp, water temp, run time, etc. These engine are sensitive to the correct amount of oil. Make sure that the engine is not even slightly over filled. In fact we routinely tell people to fill the oil level only mid way between the hash marks on the stick."
 
"The motor is not moved from o

"The motor is not moved from one boat to another its always on the same boat. the motor was tilted in on the first hole and so it was in angle like that of the transom of the boat. if you use it in this position does the oil goes from the oil pan to the piston and so it gets burnt? do you have to always use the motor in a position that the cavitation plate is parallel to the sea surface? i told you about after how much time you can check the oil level because if its oil with thicker viscosity it takes longer to drain all in the oil pan. and if he used thicker viscosity oil, if there is a small leak we wont notice."
 
""if you use it in this po

""if you use it in this position does the oil goes from the oil pan to the piston and so it gets burnt?"

The oil circulates throughout the block. It does not get burnt...At least not in a significant amount.

"do you have to always use the motor in a position that the cavitation plate is parallel to the sea surface?"

No, see your owners manual as it explains the optimum setting.

"i told you about after how much time you can check the oil level because if its oil with thicker viscosity it takes longer to drain all in the oil pan. and if he used thicker viscosity oil, if there is a small leak we wont notice."

No, it would not take longer to settle...Unless he used some imaginary oil that has the viscosity of jello.

Mark, you are overthinking this. But, if you are truly concerned you should take the engine into another dealer and have them check it. That three year warranty is there for your piece of mind. You paid for it in the purchase price of the engine so you might as well use it. Personally, I don't think there is anything wrong with the engine based on the history you provided. But, its always possible."
 
ok thanks. but the weird thing

ok thanks. but the weird thing is that the oil level red light lit 3 times and when we checked the oil level was very low. if the light didn t lit we could say that we saw the dip stick wrong but with the red light you can t be wrong. now we use it another time in the position angle to the transom and see what happens. if nothing happens we change the oil to the one we were using and see what will happen. if nothing happens than its a mystery where the oil was going. we nearly used a litre of oil topping it up in aproximtly using the motor for 10 times.
Thanks again for your immediate replies.
 
"The pressure switch, which se

"The pressure switch, which sends the signal to the light, may have some debris in it or you may have a bad ground on the light itself. Are you taking the engine on and off the boat or does it stay on the back?"
 
the motor stays on the back of

the motor stays on the back of the boat except when we take the motor to the mechanic. i dont think its the light because when it went on the oil level was really below the minimum mark. we will use it for more time weather permitting and let you know.
Thanks again
 
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