filters

hi got a 5hp tohatsu 4 stroke and assume it must have an oil filter fitted, but cant find any info in owners manual or online parts sites. Any info would be a big help

No oil filter.

9.8 and below 4-strokes don't use 'em. That means that you must change the oil at least every 50 hours, and drain it well, in order to get rid of any accumulating junk in the oil.

Thanks Paul, is it usual for small 4-strokes not to have oil filters? Got water in oil! have drained it well and refilled it 4 times so now oil is clear, but low oil pressure light is not going out, any idea what could be the problem???

Yes, most small 4-stroke outboards rely on frequent oil changes for clean oil. Aside from water intrusion from rain or similar, water is usually condensation of blowby gasses. Be 100% sure that the oil is never overfilled. Use only non-synthetic Type FC-W 10w-30 oil. Heavier and synthetic oils promote oil gain and condensation.

That's really good info, problem was engine got drenched in sea water , that was why I was thinking gummed up oil filter being a cause of the oil light not going off. could be an electrical / sensor problem ??

Yes, likely a bad sender. You can test the actual pressure with a gauge, by removing the oil light sender and temporarily installing the gauge. The sender comes on below about 4 psi. Normal cold oil pressure is maybe 30-40 psi. Salt water can cause all sorts of shorts that can be giving you a faulty low pressure indication. Could even be salt in the sender wire sheath. If you need a sender, they are available from any dealer, including me.

In addition, there is a mesh oil strainer, and if it's gunked-up, that could result in low oil pressure. In the shop, we would test the actual pressure, and if low, pull the power head, drop the oil pan assembly, and inspect the strainer.

Thanks again for the info Paul If I lived a bit closer I would bring the engine down to your shop, but I'm 3000 miles across the Atlantic on the west coast of Scotland. Will check out sensor and wiring, and see how it goes.