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4 stroke outboard oil

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Due for an oil change on a few smaller outboards, seems 10 30 is recommended, and there is plenty of that to Choose from, but then there is marine branded oils which were not in stock. They claim to have more corrosion resistance etc.Is it any different or worth paying extra for, I am talking about 2;4;and 10 hp motors, that get used occasionally and mostly at no more than half throttle.

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my honda 2hp 4 stroke 250ml of 10/30 normal car oil,how can the internals corrode unless the salt water gets in,Which it shouldnt,only the outside can corrode, the only internal which can corrode is the pump housing,waterways etc,oil does not protect those parts,hondas are air cooled so no saltwater internally anyway.

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It is not about the oil quality as such. It is about whether and engine has an oil filter or not. Most small motors do not have filters.
For any engine that has a Filter, you need an Oil with a detergent in it. The Detergent keeps the Particulates in suspension and as the oil passes through the Filter, the particles are removed.
For engines that do not have a filter, you don't want the particulates to be floating in the oil to be pumped around the internals of the engine to attack all the those important little parts. You want the particles to settle to the bottom of the Oil Sump so they stay away from all the goodies in the engine and then when you drain the oil, the particles are removed with the oil.
These kind of Oils are not so easy to come by at the normal places like the Supercheap/Repco's and is often why some Outboard makers have their own brand of oil. Which isn't really their own Oil, it is still made by the main players and they simply rebottle it in their own name. Anyone dealing with small motors, like Lawn Mowers will have these kind of Oils also. Although I have no clue as to the quality of a lawn mower oil when compared to a Brand name Outboard oil.
It is not critical. Any Oil is better than no oil. And by the way, Super Cheap and Repco have some very good oils in their range. Penrite is one of the best brands on the planet and they both have all the main names. They also have El Cheapo oils, but even cheap ones are not that bad these days.

When it comes to 2 stroke Oils, that is a whole nuther story. The are big differences mainly due to the operating temperatures of the engines. Outboards being different to a motorbike for instance. And as there is Air being drawn through the enigine with the Fuel/Oil mix, Anti corrosion additives are very different between the two.

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Just got rated in a new aircraft that has a Rotax 912 ULS motor, until now I've only used Lycomings. It requires '10W-40 for light sport 4 stroke engines'. Not sure what the difference between that and std 10W-40 is but they are insistent you don't use any random 10W-40.


Maybe it has an additive that helps with fast temperature changes?? he say trying to think why.


It's a funny motor, you have to 'Burb' it each preflight. You can check the oil level and it'll show empty but then you slowly (and very carefully after checking all masters are off) rotate the prop until you hear the motor make a very pronounced burbling noise. Check the oil level and all is usually sweet as.

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