How often do you change your gearbox oil?

westernman

westernman

Well-Known Member
Joined
23 Sep 2008
Messages
14,667
Location
Costa Brava
Visit site
According to my service manual it should be done every 300 hours or every year which ever shorter. It seems to be overkill - the oil always looks fresh, clean and unused.

How often do you change yours?
 
Oil in circulation in a closed machine without a source of external contaminants, as would be the case with an internal combustion engine, may run incredible periods without oil degradation, nor need to change it. So if it is clear and bright then it is doing its job, but the check should be after a good run, when any heavy contaminants will have been disturbed, but do allow for air bubbles making the oil look cloudy.

This is not to say manufacturers service intervals should not be observed, but common sense for a gearbox seeing less than 100 hours per year may easily be expected to run for several years without a change.
 
You don't say what kind of gearbox it is. For a sail drive I would definitely drain it annually to check whether any water had got in. If found clear, then maybe put it back in?
 
Never have yet - Kindred Spirit's gearbox emptied itself into the bilge after a couple of years and forced the issue on us :)

Pete
 
I've a TMC 40p gearbox and misread the manual so thought it was every 250 hours but was in fact "or yearly". I didn't change the oil for three years (after the initial "first service" change) but it always looked clean on the dipstick when I did the engine check. When I did change it it was actually quite a bit darker red and a little more cloudy (it's ATF) than I thought it would be but I made sure it was all out and put fresh in. I doubt any harm has been done if only slightly overdue. It's such a simple job and hardly costs a lot that it's really not worth skimping on it IMO.
 
The oil wont degrade over a year the issue with a G/Box is the metallic particles that will accumulate in the oil. In large quantities they can speed up the wear on the components but more importantly the concentration of them is a good indicator of G/Box health. The more abuse you give your box the more metal filings you will create. Flushing them out is a good thing plus as stated lets you see visually what state your components are in without stripping the box down. Flushing out the oil also lets you see if you have water ingress or other issues. For the cost of a few litres of oil compared to all the other costs involved in G/Box's and boating in general I would follow the manufacturers schedule.
 
My perkins M92b needs the engine oil every 500 hours and the gearbox every 250 hours or annually which ever comes sooner. The oil in the box was dirty when i last changed it
 
Isn't the point that unlike a normal car gearbox, you have wearing components i.e. clutches in the box?
Cone clutches in some, flat disc packs in ZF-Hurth) and VP (rebadged ZF anyway) boxes.
Anyway for the sake of 10 minutes work and 350ml of oil I'm happy to do mine annually!
The VW DSG (and others I can't name no doubt) 6 speed automatic gear change car gearboxes DO have clutches in them and are specified for quite frequent oil changes (at £250 a time!) for the same reason. (The VW 7 speed DSG has the clutches outside the box and the oil is for life as with the manual gearboxes.)
 
You know I'm really embarrassed about this and am usually meticulous about maintenance, engine oil every 200 etc, but I've never changed my gearbox oil. PRM 500, 11000 hours! Gosh. Major blind spot. The drain plug is magnetic, be interesting to see what's on it. The first thing the engineers do on dismantling is to squeeze a handful of oil to see if its degraded/burnt.
 
BabaYaga said:
Beta Marine states in their manual for the mini series: Change after 750 hrs.
Click to expand...

You are right ( I just checked my beta manual). I think that is where I got confused. The gearbox manual states every 500 operating hours or yearly. How does the beta manual know what gearbox you have?
 
For peace of mind, it's hard not to do as recommended by the manufacturer. Probably the most common reason for oil to degrade is by being cooked, ie, overheated. That's probably unlikely in a leisure marine gearbox. The next reason is losing its properties due to having its molecules cut by the action of gearmeshing, for example. Also unlikely in our applications. There's always a risk of the oil carrying (metalic) contamination particles and causing wear and damage. I struggle to think of this as being an annual event. It is probably a good idea to check once a season for the ingress of water.

I meticuously change engine oil once a year but not gearbox and I'm not going to lose sleep over it, either. Every now and again (once or twice a season) I like to measure temperatures of the engine and gearbox with an infrared gun; if they are low and stable, there's not a lot to worry about.
 
I've got a PRM 150 hydraulic gearbox, which uses engine oil. Usually changed every 300 hrs. On my Atlantic Circuit we did a lot of motoring. The 100 hour engine oil change came round monthly.
 
You must log in or register to reply here.

Share this page

Top