Questions on gear oil, trolling time, and how to use engine

[alphadog808]

Hi guys,
I was wondering if anyone might be able to give me any insight on these 4 questions...

1) I'm planning on changing out the gear oil on a 82 Johnson 70HP(j70elcnb) and a Suzuki DT4(I think-it has a 4 on it). Any idea roughly how much gear oil I'll need to change them both out? Is one quart enough for both engines?

2) I was told to use 80W-90 gear oil. Is it ok to use regular 80w-90 or should I spend a bit more(actually a lot more) on the Penzoil MARINE 80w-90?

3) The Johnson we got is outfitted with a 12 gallon tank. I know this depends on how you run the engine, but assuming you troll at a medium speed continuously, about how long can you go? Just ballpark..5 hours? 10 hours? 2 hours?

4) From an engine perspective, is it better to leave the engine running in idle, a very slow troll, or just turn off the engine completely? As an example, let's say we plan on drifting slow for 1/2 - 1 hour, what would be best? I'd figure a continuous slow troll?

Thanks so much in advance...SO much to learn!!

 

[dingbat]

Re: Questions on gear oil, trolling time, and how to use engine

My experience is with 150Hp and above outboards but here goes.

No idea how much oil you'll need. The owner's manual should give you both the quantity and quality of the oil required. FWIW: All the motors I've run required a quart each.

Lower unit oil are formulaed differently to better deal with water intrusion. I can buy quarts of Mercury High performance gear lube for $6.99 a quart. Can't see running something other than an approved lower unit oil to save a buck or two a year in operating cost. What does a new lower unit cost?

Lot bigger motor, lot bigger boat, but I burn @ 1.5 -2 gallons per hour on the troll @ 3 kts.

We've proven to ourselves time and time again that idling over fish will turn off a bite. The only time I leave the motor running while drifting is when there is a constant need to maneuver the boat around obstruction, i.e. bridge pilings. Otherwise idling on the drift is a no-no for me.

 

[Tacklewasher]

Re: Questions on gear oil, trolling time, and how to use engine

Is there a reason you don't want to use the suzuki to troll?

I have a 115 Evin and a 10 hp Honda. The 115 gets me there and then I troll with the 10hp. Have the steering hooked together so I can set the speed and troll.

I don't drift in this boat. If I were to go where I was drifting, I have a 55lb to reposition.

Every boat needs 3 motors.

 

[alphadog808]

Re: Questions on gear oil, trolling time, and how to use engine

Thanks for the input guys!

In any case, I changed out the gear oil on both the Johnson and Suzuki last night, neither one takes much oil, I was able to fill both with a one quart bottle and have a lot left over! So that was nice.

Ding, good point on spending a little more on preventative maintainance rather than maintainance; one thing I'm learning is repairs are $$!!!

TW, the boat came with the Suzuki as a kicker, just in case the Johnson dies out there. I guess we could use it for trolling, but I'd rather keep it as an "ace in the hole" when/if the time comes...

Thanks so much for the insight guys!
Jon

 

[5150abf]

Re: Questions on gear oil, trolling time, and how to use engine

Something isn't right if you filled 2 lowers with 1 quart, I have an Evinrude 50 and it takes almost a quart by itself.

You removed both screws and filled them from the bottom hole till it came out the top?

 

[alphadog808]

Re: Questions on gear oil, trolling time, and how to use engine

Something isn't right if you filled 2 lowers with 1 quart, I have an Evinrude 50 and it takes almost a quart by itself.

You removed both screws and filled them from the bottom hole till it came out the top?

Hmm..Yup, removed both screws and let it drain for 5mins+. Filled it from the bottom till the top had oil coming out. Even went so far as to recheck it later to see if there was any settling.

I had a pump connected to the quart of oil, it felt like I did about 12 or so pumps before it filled. Also, I didn't notice that much oil coming out. And it wasn't milky...which I hear is a good sign...?