Trim Pump Oil

Just a question: My good old Mercury 115 is going on to its sixteenth year of trouble-free operation. Being a maintenance freak, I check the oil in the power trim every year. It hasn't budged at all since new and still reaches the bottom of the filler neck. It looks nice and red and fresh, no apparent gunk in it. It's just that I find it hard to believe that oil (any oil, for that matter) doesn't lose its qualities with age. I was wondering whether it would be a good idea to drain the trim pump (through the manualrelief valve at the bottom of the pump) and refill with a fresh dose of automobile ATF (or Mercury Trim Oil, which is exactly the same thing except for price per pint!). The local guys at the Mercury dealership told me they never do it, and they only change the oil when for some reason they need to take a trim pump apart (not frequent, but it happens).

Anybody have strong views about the issue? Thanks!

Re: Trim Pump Oil

If it ain't broke, fix it until it is.

I'd leave it alone. It's happy, you're happy, it's a sealed system that won't affect other parts (unlike for example a LU failure). For the minimal use they get (a few seconds a trip) the fluid doesn't have to be in the best shape. But drain and refill, you might somehow disturb a seal. And I know from salt water applications that getting into an old one to fix it is often the end of the unit.

Re: Trim Pump Oil

The gear oil in an auto manual transmission lasts indefinitely. So the answer to your question is as long as it is still clear and not milky, you may leave it alone.

Re: Trim Pump Oil

I would not do it. Sometimes you're better not touching what's working. Anyway, it will not work better after you change the oil...
Don't touch it...

Re: Trim Pump Oil

Pascastel said:

I would not do it. Sometimes you're better not touching what's working. Anyway, it will not work better after you change the oil...
Don't touch it...

Click to expand...

I learned a long time ago just what Pas said. "If it ain't broke don't fix it". My Merc service manual says nothing about periodically changing the oil in the unit. It does say that if adding fluid, check the color of the fluid. If red use ATF and if clear, Quicksiver TT oil.

HTH,

Mark

Re: Trim Pump Oil

Thanks guys, I was tempted to do that, and you have further convinced me! In truth, I notice that the manufacturer of my car (a Mercedes) recommend one automatic shift change at 30,000 miles, and then that's it for the rest of its life. Same theory I guess.