Re: Suitable Lower Unit Oil for 1971 Johnson 6 HP
I think someone needs to go look up the ingredients of the oils, auto v marine. its the same stuff.
you might get a shock as to whats in them under the fancy labels.
oil spec sheets are easy to obtain !!!
I have used normal hypoid ep 90 in a outboard gearbox for years and never ever had a problem with it.
regular checks for the oil are needed anyway, so it is not like on a car where nobody ever even bothers to check it.
I change gear oil on a 2 yearly basis unless I have done a lot of hours.
if you actually look in a proper service manual for outboard engines it will specify what oils to use, this will give names of brands and the specs of the oil for instance sae 75w or hypoid ep 90 etc etc , now all oil companies that use the sae marking have the oil at the same viscosity and the same specification. that is why they have the specs !!!
mercury recommend mercury oil, but they don't actually make any oil, omc recommended their oil, yet again no omc oil refinery. the list goes on.
so where does the oil really come from ? and what exactly is it. only the spec sheet will tell you whats in it.
what do you think everyone used in the 1940's and 1950's ?
anyway that's what I do and wont be fooled into buying everything just because it says marine.
phill