if i dont know how long its been since the gear lube has been changed on the old motor i just got, is it a good idea to go ahead and change it? how often should it be changed out? any suggestions on a specific type or brand of lube to use on an old 78 johnson? is it ok to just throw it away, or do you need to take the old grease somewhere for recycling?

thanks!

Fry, I'd go ahead and change it now, since you dont know when it was last changed. It's cheap and not hard to do.


You can get by with the Lubrimatic (80/90W) brand for now ( walmart sells it on the boat aisle)....if you dont want to wait til Monday to see a dealer. Pic of the Lubrimatic quart bottle on this page

I usually use the OMC ( now Bombardier) brand from the dealer, that's specifically made for Evinrude/Johnson. But truth is, there isnt much difference in the major lube brands for that engine.

Get a pump from academy or walmart, and two quarts of the lube. Open both the top and bottom screws on the side of the lower unit and drain it. Pay attention to any gray or milky lube that comes out. A tiny bit will usually be there. But more than a tablespoon is not good.
Also look for metal filings. There will be some on your lower drain screw, since it's magnetic....but not much.

With your engine sitting straight, pump the new fluid in from the bottom hole until it runs out the top. Replace the top screw first, then unscrew the pump from the bottom hole and replace the screw.

As soon as you can, drop by the dealer and get two new washers that go under those two screws on your lower unit and replace them. Otherwise, you'll be changing it again real soon.

You should change the lower unit lube at least once if not twice per year. Changing it can let you keep an eye on wear and possible leaks.

You should change the oil anytime you get a new to you engine. Car, truck boat or anything else with oil. Just good easy cheam insurance.

As for how often, that's totally up to you, but they recommend once a year. I like to change mined every 25 hours of use. I change oil, clean plugs, pull prop and lube propshaft, clean bottom of the boat etc...

I figure 2 hours and $15 every 25 hours is pretty good insurance against breaking down on the water.

Just for reference, @ 25 hours my lower unit oil is just changinf from green to black, when I put it in a clear container it looks nealy black, but on my finger it looks green. When I first got the boat it was so black I almost thought it was the original oil from '98

I do mine every year before the first freeze, so in case it has taken on water, it won't crack the gearcase open. Go ahead & do it now.

Autozone will take the old oil. PLEASE DON'T PUT IT IN THE SEWER OR DRAINS OR DOWN THE STREET!!

That all runs into our creeks and lakes, and where we fish!!

so what does it mean if some milky brown stuff that seems thicker than the rest comes out? Word that comes to mind is sludgy. Old lube didnt really smell bad, didnt notice and metal fillings, but did notice the milky stuff.

does that mean water was getting in there? If so, the top washer was kind of messed up, so i guess that could be the reason. Im replacing both. If it is water, would changing the gear lube often clear up the problem?

thanks,
T

the seal in the lower unit could be bad.........

oil with water in it has a milky appearance, could be nothing more than, the former owner(s) went years without changing it.

still have the old oil? put it in a clear container (2 liter coke bottle for example), if there's any water in there, it'll collect at the bottom within a day or so.

change the drain & vent washers, then drain some of the oil after your next outing to check for water.

was there metal in the oil? some shavings on the drain plug magnet is normal.

not really any metal in the oil, but there was some on the drain plug, maybe a fleck or two in the oil, but dragging my finger through it didnt leave any metal on my finger.

thats a good idea to put it in a bottle to check for water, i'll drain and refill it soon and see if its got water in it, its such a quick easy job, wouldnt hurt to change it in a month or two just to check i guess.

i gotta say, this '78 johnson 70hp is pretty impressive so far, 30 years old and still kicking hard, suprising.

every year cheap insurance

Make sure your Johnson does not have electric shift. Some models of Johnson/Evinrudes built in the 70's used electric shift, which requires a special lube oil. I had a 72 Evinrude that required this. Dont ask me why. Just what the mechanic told me. Maybe 78' was late enough that they finally figured out how stupid it was.

its called premium blend also used in hydro mechanical gear cases i believe through 1976