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MG Midget and Sprite Technical - OIl advice?

Hi all,
due for the annual oil drop soon, but was wondering.
Friend of mine said that gearbox oil should NOT be routinely changed...is that right?
It's not a huge problem to change the gearbox oil, I just wonder if I SHOULD?
Car does about 3 K miles per annum max.
Grateful for any advice here.
Oh yes, Millers / Halfords or Castrol ??- currently she is a Castrol user.
Cheers all
colin
colin frowen

"Friend of mine said that gearbox oil should NOT be routinely changed...is that right?"

Assuming a BMC/BL/Triumph box and not a T9 conversion.

Depends on what he meant by "routinely". Every 3k/year? No, just check the level, but not really needed at such low mileage use if you don't see drips that make you suspect you've lost oil. -- Unless you haven't changed it in 5 years say (15k miles).

Given that these boxes shed metal particles internally sufficient to contaminate the oil quite quickly, the oil runs hot, and gets knackered between the gears, I used to change the oil at around 15K in an attempt to make the box last longer than the average 60/70K I ever got out of them.

Assuming you have a 1098/1275 box, 20:50 engine oil.

If you have the triumph box it's an EP oil. 80 I think, but someone will correct me if it's a 90 weight.

Lawrence Slater

Your friend has an interesting point with some validation...if I understand his primese correctly

This mainly applies to engines but im sure it can be applied to the ribby 4 speeds as well

Because gear box oil rarely gets changed and has no filtering, it builds up a heavy sludge so after 60,000 miles the bearings are worn and the sludge acts as gap filler, you remove the old oil/sludge and replace with clean new oil... and you loose the gap filler sludge, and 600 miles later ... bang goes the engine/ribby transmission

But ... if the oil is changed on a regular schedule then there wont be an issue

Prop
Prop and the Blackhole Midget

Colin,
I think it's the thoroughness of an oil change that's as important as the frequency - getting the existing oil as hot as possible before draining and leaving to drain for as long as possible to get out as much of the existing oil and muck out as possible

engine oil in the gearbox isn't going to be as robust as gear oil so I think you should look a thorough change every 2 or 3 years (the MGB factory Workshop Manual has to change the (engine) oil in the gearbox every 2 years or 24k-miles

as for which oil I think the Castrol, Halfords or Millers are all fine so stick with the one you prefer

at 3k-miles per year you certainly need to change your oil in the engine thoroughly and regularly, at least every 6 months

I also think that the changing (and thoroughness) of diff oil is usually overlooked, another poster put that he changed his diff oil every year and the whine it had went away

I think if you don't have a whine then as changing the diff oil, like the g/box, is so easy and inexpensive that you could look at a thorough change every 3 years if using mineral oil but for longer lasting oil with reduced cold weather drag I'd strongly recommend you use a modern alternative like the excellent Mobilube 1 SHC 75W-90 (GL5 spec*) and change say every 3-5 years

(*GL4 spec oil is recommend for the gearboxes but the more modern GL-5 is considered fine for the diffs and if you get mineral 75w90 or 80w90 it'll be GL-5 too)
Nigel Atkins

Any thoughts as to head light oil ? It might be time to change mine... the light seems a little dirtier then normal
Prop and the Blackhole Midget

Hi All
Cheers
Colin
colin frowen

This thread was discussed between 18/12/2014 and 19/12/2014

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