Question about Merc Trim and Steering fluid.

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Ok... full story...

Replaced the trim pump reservoir about 4 years ago. New reservoir cost me $180!!! :eek:

Trim pump's leaking again, just slowly. So I pull the pump, thinking it's just the reservoir 'O' ring. Get a new 'O' ring and fit it up (previous 'O' ring, supplied with the new reservoir, WAS the wrong size :facepalm:). Tip the pump over at 45? and voila... it's leaking :facepalm: but not the new 'O' ring, the 'seam' between the top and bottom parts of the reservoir. Bugger! There's no way I'm paying $180 again... So I notice a Parker Hydraulics logo and a part number on the reservoir. I find out that this Mercruiser trim pump is just a badged up Parker 108 series pump... Fantastic! Called the local Parker agents in Australia. Yep, they got them, only $59... Yes please, I'll have one... :D

So... The question... The pump contained 'Mercruiser Trim and Power Steering Fluid'. Looks just like a light weight oil to me, but.... Reading up Merc say to use their fluid (no really surprise there, ah), or in a pinch use 10W30 or 10W40... So, what ACTUALLY is Merc's Trim and steering fluid? Is it one of those oils?

One more question ('cause I'm real dumb). I have a bottle ('bout 1.5 litres) of Shell Helix 10W50 Full Synthetic. Can I just use that, or do I need to clean ALL of the oil out of the hoses and rams too? ie, can I mix the original ??? with this fully synthetic?

Thanks for your patience guys.... And sorry for 'another oil thread' (but I think this one is a little different, I hope)...

Chris.......
 

a1nowell

Chief Petty Officer
Joined
May 12, 2009
Messages
437
Re: Question about Merc Trim and Steering fluid.

Chris,
I use 10w30 and it works fine.

If you now have a new Parker pump, I'd call Parker and ask them what to use.

I would not mix synthetic and regular oil.

Thanks,

Larry
 

HT32BSX115

Supreme Mariner
Joined
Dec 8, 2005
Messages
10,083
Re: Question about Merc Trim and Steering fluid.

('cause I'm real dumb).
Now NONE of us actually believe that Chris!!:D


I have a bottle ('bout 1.5 litres) of Shell Helix 10W50 Full Synthetic. Can I just use that, or do I need to clean ALL of the oil out of the hoses and rams too? ie, can I mix the original ??? with this fully synthetic?

Thanks for your patience guys.... And sorry for 'another oil thread' (but I think this one is a little different, I hope)...

Chris.......

This is a "GOOD oil thread"!!



These trim systems are SUPER simple hydraulic pumps and cylinders.

Just about ANY petroleum based oil can be (and has been) used. Even Mercruiser (in their service manuals) indicated that motor oil can be used in the trim system.

I have always used ATF (Automatic Transmission Fluid) just because it's RED. So if there's a leak it can be identified readily.

All motor oils can be mixed too (EXCEPT for Cat-converter vs NON-cat-converter engines [when used in actual engines!!] etc.....Don't mix certain synthetic gear oils with NON-synthetic gear oils either etc......)

You won't hurt a thing mixing syn and NON-syn in any hydraulic system. If I lived in a VERY cold climate, and I was using motor oil in my trim system, I would absolutely use synthetic oil because it wouldn't turn to "jello" in sub zero temps. (I don't what I'd with the boat when it's FROZEN in the dock though!!:facepalm: )
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,256
Re: Question about Merc Trim and Steering fluid.

Now NONE of us actually believe that Chris!!:D




This is a "GOOD oil thread"!!



These trim systems are SUPER simple hydraulic pumps and cylinders.

Just about ANY petroleum based oil can be (and has been) used. Even Mercruiser (in their service manuals) indicated that motor oil can be used in the trim system.

I have always used ATF (Automatic Transmission Fluid) just because it's RED. So if there's a leak it can be identified readily.

All motor oils can be mixed too (EXCEPT for Cat-converter vs NON-cat-converter engines [when used in actual engines!!] etc.....Don't mix certain synthetic gear oils with NON-synthetic gear oils either etc......)

You won't hurt a thing mixing syn and NON-syn in any hydraulic system. If I lived in a VERY cold climate, and I was using motor oil in my trim system, I would absolutely use synthetic oil because it wouldn't turn to "jello" in sub zero temps. (I don't what I'd with the boat when it's FROZEN in the dock though!!:facepalm: )

Ayuh,... Seein's this is a Good oil thread, I'll just jump right in early, 'n muddy the petrol...

I agree with Rick, trim systems are 'bout the simplest hyd. circuits out there, 'n will work just fine with Any reasonably light weight oil...

I use the ATF I buy for my pick up, or the Hyd. oil outa the 55 gallon drum out in the garage,...
'n yes, I've mixed 'em...

Syn-oils are the cat's meow, superior over dino-oils I think...
I use nothin' but Syn-oil in my drive, 'n boat motor...
everything else get's the fleet oils...
'n to date, I've never had any sorta adverse reaction from mixin' syn-oil, with dino-oil...
 

HT32BSX115

Supreme Mariner
Joined
Dec 8, 2005
Messages
10,083
Re: Question about Merc Trim and Steering fluid.

'n to date, I've never had any sorta adverse reaction from mixin' syn-oil, with dino-oil...

I agree.

I would like to know what the deal is with GEAR oil though. I have noticed that some syn gear oils precipitate some sort of "stuff" out of them (that maybe mixes right back in if heated) if they sit for long periods of time.....like in a Mercruiser Drive lube reservoir ........ (Mobil-1 Gear Oil excepted)
 
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