Gear oil

[Philpy]

I know this subject has been addressed a fair bit in the past, but I wanted to run this past you.
Now I know Seagull state SAE 140 for the gearbox, but this proves difficult or expensive to find.
After a bit of googling, I found a New Zealand website where they state that:
The biggest gearbox problem by far is internal corrosion. The manufacturer recommends heavy gear lube oils like EP-140 or SAE-140. These oils have 2x major issues;

1. they don’t address the corrosion problem faced in the real world, &
2. they create alot of internal viscous lossess that reduce useful power to the propeller

The manufacturers reccomendations were made with the best knowledge & materials of the day, but, that era that has been surpassed. Oil technology has advanced hugely including, the use of dispersants & friction modifiers. Unlike gear oils, modern engine lube oils contain dispersants & emulsifiers. These give the oil better ability to suspend leakage water as a relatively harmless homogenized solution. Without dispersants the water has more tendency over time to separate out from the emulsion. So given all this, use a thinner oil such as ordinary modern engine lube oil SAE 10w40. Note that thin oil also tends to leak out faster & leak water in faster, this is especially the case in worn gearcases. Important you change it after every outing.

* The ordinary modern engine lube oils like SAE 10w40 will reduce internal viscous losses resulting in greater useful power to the propeller.


So questions is, has anyone used a normal engine oil like 10w 40 in a gearbox? I can see it will soon wash out, but not worried about if I have to change it everytime... Only use it a few times a year!

[Keith.P]

The problem is if you use a 10w:40 oil on a standard unsealed gearbox, it will just run out as fast as you fill it.
The biggest problem is sea water for internal corrosion by far, some of my motors use grease to stop any loss in the gearbox and one of my motors uses about four pints of oil in its gearbox, so power loss will be factored in to the deign, as they are deigned as a plodder, rather then a racing motor.

[headdownarseup]

I've used 10w40 motor oil in a 102 gearbox before now.(it can get a bit noisey at times due to the thinner oil)
Not quite so much of a problem if you only use the motor a couple of times a year.
But you should really try to stick with the 140 grade of oils, or the 90 grade for the later sealed gearboxes.
Oil will always be cheaper than a new set of gears!

jon

[headdownarseup]

another thought PHILPY

you'll never catch H-A in the LERRYN race. He's too damn fast

When you get a spare weekend, strip your gearbox right down and carefully check ALL of the bushings/bearings. Depending on which gearbox your using, the pinion drive bearing is a common one that wears out. You might find you have to get custom made bushes/bearings made up to cure the problems.
Have a word with the resident "racers" on here. They can offer far more advise than i can. CHARLES and H-A should be able to help in one way or another.

jon

[Philpy]

Ha, I think your right, unless I build my own boat like HA!

Been and bought some SAE 140 today, was just looking for a cheaper alternative as one of my gearboxes must be fairly worn as lets a fair bit of water in!

[Adrian Dale]

As you are in the UK you shouldn't have too much trouble sourcing the right oil but do make sure it will emulsify. Put a 100 mm in a flask then add 50mm water, whisk until all the water is in suspension then let it settle for a few days; the water and oil may part thus in the gearbox on the rack in the shed, salt water will be covering the lower half the gear wheel causing corrosion. next time you use it, even if you top up with fresh oil the damage will have been done and gear failure will rapidly follow. In a good tight emulsion the water won't separate even after a month or more thus no corrosion. Yes the oil is expensive but it will save you shed loads of time and money in the long run

I use my gulls for regular trips up and down the Chanel, stopping off at the odd shack on the way, often this means long running times in access of 4 or 5 hours with out top up or draining. Just in November on such a trip, I damaged a gearbox by the wrong oil and was faced with a rebuild and a spares order from SOS in the UK. That oil was Penrite 140. Penrite have actually stated that their oil is not suitable for gearboxes were water ingress may occur. Unfortunately I had not read the post that warned against its use.

It is my intention to do a 16+ hour non stop run later this month using just one fill of oil. I will post the results. The oil I am currently using is Shell Strombus MP

AJ

[notav8]

I recently purchased a grubby old 102. Previous owner informed me that he had run the engine a couple of years ago. Before starting it, he had checked it over, changed the gearbox oil, using Penrite gear oil, and ran the engine in water, to make sure all was working.
The motor was then put back in the shed.
When I got it home, I noticed that the prop would not turn. I hadn't thought to check it when picking it up. I looked inside the gearbox, and it looked clean. I touched the oil with a bit of wire, and it looked new. I decided to tip it out, as I thought I would have to dismantle the gearbox. When I tipped the engine over, the gearbox had clean water and oil. About half and half. There was definitely no sign of emulsion. I have since refilled the gearbox with 90 oil, and spent a couple of hours carefully freeing up the gearbox prop shaft. It now works fine. I hope that there is not too much rust damage, to the gears.
I hope to give it a run soon.
Cheers,

[Gannet]

I have had a similar experience of acquiring an engine with an unknown oil and some water in the gearbox.

My pragmatic take on this emulsion issue, is after using your oil of choice, drain the resultant emulsion into a jar and leave it for weeks or months.
Periodically look at it and see how it is separating out.
My experience is that it will sooner or later (and time scale is very important), separate out with oil in the top layer and water in the bottom layer. (The layers between will be a water in oil emulsion and an oil in water emulsion.)
My suggestion is that the bottom water layer will cause corrosion problems.
The speed in which it separates out will be a very good indication of the oil's suitability for short term storage. Presumable different oils will separate out at different rates.
Jeremy

[Adrian Dale]

Exactly, Penrite won't emulsify. see the two photos attached, both had 20% water added which was whisked to get a good even mix then left for 48 hours, when the photos were taken, the Penrite separated; the MP did not and in fact it remained as an emulsion in the same jug for over a month before I disposed of it. This is a tight emulsion and if I had left it for longer it would have remain in that state.

Sorry, been trying to up load the photos but our internet conection is so slow that it is not possible to do so very annoying. I will try tomorrow

AJ

[Gannet]

Adrian,
Yes, an excellent suitability test.

Keeping the used drained emulsion in a jar enables one to evaluate how the actual lubricant mix is performing.
I look forward to hearing about your planned Bruny Island trip and It will be interesting to know what the emulsion was like at the end.
Jeremy

[erle bartlett]

I use my gulls for regular trips up and down the Chanel, stopping off at the odd shack on the way, often this means long running times in access of 4 or 5 hours with out top up or draining. Just in November on such a trip, I damaged a gearbox by the wrong oil and was faced with a rebuild and a spares order from SOS in the UK. That oil was Penrite 140. Penrite have actually stated that their oil is not suitable for gearboxes were water ingress may occur. Unfortunately I had not read the post that warned against its use.
AJ

What sort of damage did you get? Gears? Shaft/bushes?

[Stelios_Rjk]

Damages that could occur is rusty gears and gearbox (internally). How far will this go depends on the period of exposure, freshwater/saltwater.

Since the oil or greasy stuff doesn't emulsify properly, it remain thicker and won't reach the bushes to lubricate them. So gears are lubricated, bearings runs on water and gets worn. I have seen such gearbox, shaft has free play of 1mm or a bit more.

Shaft is the last thing that will be damaged, by this time gears or bushes will have serious issues. And of course oil will drip out immediately.

So SAE or EP 140 for plain gearboxes. SAE or EP 90 for sealed ones. 250 for worn bushes or hot waters is recommended by Seagull.
I mix cheap yellow grease with 140 if I can't source 250 for leaky gearboxes. The mixture should always be liquid, not like grease. More like honey.

[Adrian Dale]

The damage was to the main bushing which inturn increased the back lash on the pinion. It was the pinion that became quite badly worn. As I am intending to use this engine for an extended run I wanted the gear box to be in very good condition with good even tooth contact thus I change all the internals. I believe the chaps on the Murray river run (November 2013) had similar problems and were forced to change several gearboxes on the way down.

AJ

[erle bartlett]

Bugger! Guess who bought the Penrite... Looks like I'll be looking for some Shell Strombus before I do any great damage.

Thanks for the info.

[Adrian Dale]

This is what I use now.
AJ