What viscosity gearbox oil in a Johnson 6hp 4-stroke?

[NickC]

Can anyone suggest what spec of gearbox oil I should use in our Johnson 6hp 4-stroke? Engine oil spec is fine book says 10W/40 or 10W/50 but makes no mention of what viscosity gearbox oil should be used.

Thanks,
Nick

 

[VicS]

Can anyone suggest what spec of gearbox oil I should use in our Johnson 6hp 4-stroke? Engine oil spec is fine book says 10W/40 or 10W/50 but makes no mention of what viscosity gearbox oil should be used.

Thanks,
Nick

Outboard engine gear oil is a GL5 oil about EP 80 or EP90. With the notable exceptions of Seagulls and OMC electric shifts

Compared with automotive oil it contains additional inhibitors and emulsifiers to counter the effects of any water which may enter.

The best advice is to use an oil such as Quicksilver Premium Outboard gear oil or the equivalent BRP/Johnson/Evinrude product. ( It used to be OMC HiVis gear oil)

If you must economise then use an automotive EP 90 gear oil.

 

[NickC]

So sounds like really worth getting a marine oil rather than an automotive one then.

 

[lynall]

Would be interested to know how the marine trans oil deals with water ingress compared to an automotive trans oil?



Lynall

 

[gljnr1983]

+1 i have read on a us forum that there is just a dye added so you can see leaks with ease.If there is a difference in handling water intrusion it would be good to know the additive used.

 

[VicS]

+1 i have read on a us forum that there is just a dye added so you can see leaks with ease.If there is a difference in handling water intrusion it would be good to know the additive used.

They tell us that an outboard gear oil contains corrosion inhibitors to counter the effects of water ingress and also emulsifiers to keep any water emulsified .

I am not aware of there being a dye added to aid leak detection. You can see oil leaking easliy enough i would have thought.
Many oil manufacturers do colour their oils though.




I use an EP 90 automotive oil


Useful video at http://www.youtube.com/watch?v=AqQvbXV1Cw4


.

 

[NickC]

Hmm.. so not just me that wonders if there really is any difference between automotive and marine EP80/90 then. We need an oil expert to help answer this.

Thinking about this if we compare two applications between say a car differential and an outboat:
A car diff has a very small breather hole and probably draws in a certain amount of condensation as it heats and cools throughout a day. I assume an outboat must also have a system of breathing air in/out much the same way as the oil expands and contracts, or does it? The only other difference I can see is the possible adition of salt to the equation.

Nick

 

[VicS]

Hmm.. so not just me that wonders if there really is any difference between automotive and marine EP80/90 then. We need an oil expert to help answer this.

Thinking about this if we compare two applications between say a car differential and an outboat:
A car diff has a very small breather hole and probably draws in a certain amount of condensation as it heats and cools throughout a day. I assume an outboat must also have a system of breathing air in/out much the same way as the oil expands and contracts, or does it? The only other difference I can see is the possible adition of salt to the equation.

Nick

A car diff has a breather but an outboard gearbox doesn't. It is water cooled so the oil wont tend to heat up much.

The main reason to change the gear oil in an outboard regularly is to check it for water ingress. Free water or milky oil indicates the need to replace seals.

I have never come across any indication of water in a car diff .... it gets hot enough to drive off any condensation should it occur.

On fresh water you might live with a little water ingress into an outboard gear box but it would be inadvisable to risk corrosion caused by salt water ingress

 

[lynall]

I have changed emulsified oil in truck diffs a few times now, one of the trucks being a large sewer sucker and it was the clean water tanks (luckily) that were leaking right onto the diff breather and entering the oil, basically it went milky as always.
I suspect that it had been like this for many months and but i found it, and we still see it, so obviously the diff survived.
Only other ive seen is my land rover where it got a bit wet.
I dont know what temp they run at buts its low, as even after a days work you can bear your hand on it no problem at all, gearboxes run a lot hotter.
I wonder how they get on without a breather as if a truck or car one blocks the seals then tend to start leaking.


Lynall