Diff oil - after 55K miles, how is it supposed to look?

Technical Area Engine, Transmission, Exhaust etc
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  1. My model of MX-5 is: __NC3 2.0
  2. I’m based near: __Orpington
  3. I’m looking for technical help or recommendations on: __diff oil appearance

Just changed mine yesterday, and it was looking pretty good - as in no black sludge coming out, rather oily and not that discoloured. There were some signs of tiny metal particles on the magnet of the drain plug, so I wonder if it had been changed at some point and they never bothered to wipe the plug. Or if they did wipe it and the ferrous dust accumulated afterwards. Full Mazda service history, but do they even bother about the diff? I’ve seen that the long-life coolant is not a clear service item, so my expectations are low…

While on the subject, I discovered that the Lidl electric oil pump they sell works wonders to refill the diff - when adapted. You need a 12V car battery next to it of course and ditch the thin hose it comes with for sucking oil. I cut the thicker hose in half and used it instead. Worked like a dream, as opposed to the metal syringe (for gear oil!) I had and leaked everything all over. Same with a backup plastic syringe I had (for gear oil again).

4 Likes
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Get into the habit of changing it every 2nd year or 20k miles. It doesn’t look too bad, mine didn’t and you’ll get a small build up of sludge on the plug, very minor though.

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That’s a good idea for the Lidl pump. I bought one for my engine oil but I’ve not tried it yet and am now thinking gear oil is a much better use. Maybe I should get another one

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I got mine changed at about 11.000 miles but it was getting on 7 years old and it was pretty black which was worrying. Not sure why it got discoloured like that?

Thanks.

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I bought a few ketchup pumps off ebay for filling gearboxes and are heavy duty and used to pumping thicker fluids. Screw to the litre bottles of oil if you cut the pipe down inside and then put a piece of clear hose on the end, so you can stick that in the diff or gearbox. I think I paid about a tenner for 5 or something. You can dismantle and clean them and reuse again and again.

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This is the magnet out of a honda gearbox I pulled apart last week, new oil and bearing, running like new. Don’t worry about a few filings.

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My drive is not on level ground. After draining I used a 300ml syringe to pop the stated amounts of oil for the gearbox and diff. Here’s hoping :wink:

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My drive isn’t level either, but I made sure when on stands the car was level-ish.
Otherwise gearbox and diff will have the wrong amount of oil - not acceptable

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I just use a squeeze pump when doing the gearbox or diff oil.

It takes a few minutes of squeezing but it’s simply enough and only a small volume of oil.