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PRM 150 oil change


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Likewise our PRM 150 has done about 3500 hours and the oil that comes out is the same colour as the oil that goes in.  There is a small oil leak into the engine bilge, and I know it is the gearbox as it is new oil colour rather than engine oil black.  As an aside I think it leaks a bit because I have a tendency to overfill due to not being able to see the oil on the gearbox dip stick.

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On 12/11/2018 at 11:56, Flyboy said:

I'd be very worried if the oil came out of my PRM 150 gearbox black. It always comes out looking the same colour as it went in on mine.  I assume you change the oil at the correct interval.  Maybe your box is being contaminated by a leaking oil cooler or has run on a very low oil content and is overheating.  Does it have the correct oil type ie engine oil and not EP gear oil. ?

Yes I always change my oil at the correct service intervals and use the correct grade of oil that goes in my engine, not a gear oil.  It's not black but it goes in green and certainly comes out darker. It's not the same shade of green.

Edited by blackrose
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On 12/11/2018 at 18:40, cuthound said:

 

Likewise, the oil in mine is always the same colour as it went in, even after 250 use.

Perception of colour is very subjective. I'd be surprised if it's the same colour. Any wear will change the colour of your oil to some degree. The point is that if there was really no wear and no deposits in your gearbox oil after 250 hours then why would you even need any oil? 

On 13/11/2018 at 09:24, alan_fincher said:

 

^^^^^^^^^^^^^^^^
Exactly this!

Last boat had an ageing PRM Delta, (very similar to a P150).  I didn't change oil that often, but it was always the same colour as when it went in, however long it had been there.

I'd suggest that if oil in a PRM hydraulic box is turning black, there is probably something wrong with it.

In an engine it is the end products of burning the diesel that makes the oil go black.  Nothing should be being burnt in a hydraulic gearbox!

No there's nothing wrong with mine, I'm pretty sure it's fine. It doesn't get hot or anything.

Edited by blackrose
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On 13/11/2018 at 12:16, john6767 said:

Likewise our PRM 150 has done about 3500 hours and the oil that comes out is the same colour as the oil that goes in.  There is a small oil leak into the engine bilge, and I know it is the gearbox as it is new oil colour rather than engine oil black.  As an aside I think it leaks a bit because I have a tendency to overfill due to not being able to see the oil on the gearbox dip stick.

Well mine definitely comes out darker.

I think anyone who says their old gearbox oil is still exactly the same colour as when the new oil went in probably needs to go to Specsavers. 

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If I put a sample of your old gearbox oil into a densitometer I guarantee it wouldn't be the same colour as the new oil you put in.

 

The people who say it's the same colour are basically saying there is no gearbox wear or oil breakdown, in which case I'd like to ask why do you even bother to change the oil?

Edited by blackrose
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On 12/11/2018 at 08:32, Chewbacka said:

It reduces friction by putting a film of oil between the surfaces to ‘eliminate’ metal to metal contact, but in the real world there are tiny areas of highs and lows and the contact area of a ‘high’ is tiny so the pressure on the oil film at that point is greater than the film can withstand resulting in micro metal to metal contact.  So it wears away.

☝️☝️☝️☝️☝️☝️

 

Exactly this. There WILL ALWAYS be wear, and wear WILL ALWAYS result in deposits in the oil. Any deposits WILL change the colour of your oil whether you perceive that or not.

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47 minutes ago, blackrose said:

Well mine definitely comes out darker.

I think anyone who says their old gearbox oil is still exactly the same colour as when the new oil went in probably needs to go to Specsavers. 

 

36 minutes ago, blackrose said:

If I put a sample of your old gearbox oil into a densitometer I guarantee it wouldn't be the same colour as the new oil you put in.

 

The people who say it's the same colour are basically saying there is no gearbox wear or oil breakdown, in which case I'd like to ask why do you even bother to change the oil?

 

28 minutes ago, blackrose said:

☝️☝️☝️☝️☝️☝️

 

Exactly this. There WILL ALWAYS be wear, and wear WILL ALWAYS result in deposits in the oil. Any deposits WILL change the colour of your oil whether you perceive that or not.

 

You didn't "it comes out a subtly darker shade than when it went in", you said.......
 

Quote

So why does the oil in my gearbox turn black


People reacted to what you said, not what you are now saying.

You seem to have ignored the possibility that any worn metal simply sinks to the bottom, and might not noticeably change the colour of the oil.

If your oil is genuinely "black", (or even tending towards black), then I'd say you quite likely have a problem, (and a gearbox can easily fail without getting hit - that's not the only measure of a potential fail).

If it is demonstrating a very subtle change if colour, (but there is no black), then you are probably OK.  But that's not even close to what you said!

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1 hour ago, blackrose said:

Yes I always change my oil at the correct service intervals and use the correct grade of oil that goes in my engine, not a gear oil.  It's not black but it goes in green and certainly comes out darker. It's not the same shade of green.

It was you that said your oil comes out black, now you say it's not black but dark green. Make up your mind, people on here are trying to help you avoid a possible problem looming in your gearbox.

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1 hour ago, blackrose said:

Well mine definitely comes out darker.

I think anyone who says their old gearbox oil is still exactly the same colour as when the new oil went in probably needs to go to Specsavers. 

As you have not seen the oil why do you think you are qualified to say that?   I think an apology for you tone is in order.

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2 hours ago, blackrose said:

I think anyone who says their old gearbox oil is still exactly the same colour as when the new oil went in probably needs to go to Specsavers. 

Or need to put the drain plug in before trying to fill the gearbox. 

 

Don't ask me how I know this.

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I serviced a boat with an early PRM box that had an oil filter on it. Can't remember the model.

The oil came out like tar and the filter was very heavy with gunge. The oil must not of been changed for many a year.

It was running fine. With clean oil and a new filter  it didn't sound any different!

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20 hours ago, blackrose said:

☝️☝️☝️☝️☝️☝️

 

Exactly this. There WILL ALWAYS be wear, and wear WILL ALWAYS result in deposits in the oil. Any deposits WILL change the colour of your oil whether you perceive that or not.

 

No one is disagreeing with that, but you said the oil in your PRM 150 gearbox goes black. That is most unusual given there should be no combustion particles in the gearbox oil.

 

 

20 hours ago, blackrose said:

Yes I always change my oil at the correct service intervals and use the correct grade of oil that goes in my engine, not a gear oil.  It's not black but it goes in green and certainly comes out darker. It's not the same shade of green.

 

You aren't using Duckhams are you ? Most engine oils are a golden colour when they go in.

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