Sealed for life auto gearboxes

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Mon 17 Oct 2005 20:49
Sealed for life auto gearboxes - MW
Changed the auto gearbox oil on my W124 MB yesterday. 18k miles. It was just 'going a little dark red/lightish brown'. Considering most of the last two years has been urban driving, not too bad. Car feels smoother, but it's probably phychological. The beauty is, there are 2 drain plugs. The one on the sump realeased about two and a half litres. But the one on the torque convertor about three and a half.
Given the normal degredation of the oil, I am amazed that many MB cars are now sealed for life. Others are at it too.
5 litres of Commer dextron 2 was £9.99p. The gearbox is worth about £2000.
Has anyone had a 'sealed for life box' do 120,000 miles or more?
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Sat 22 Oct 2005 12:21
Sealed for life auto gearboxes - Ruperts Trooper
Dexron 2 is the old specification - get Dexron 3.

GM / Vauxhall specify no oil change, ever, on front-wheel drive autos UNLESS used in "extreme" conditions when it cshould be changed at 40,000 miles. As I tow, which is one of the "extreme" conditions, I change the auto fluid every 20,000 miles, it comes out dark red. If it comes out brown, it's overheated and needs changing more frequently.



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Sat 22 Oct 2005 18:14
Sealed for life auto gearboxes - MW
Yes I was aware of that, but as the dexron 2 was fine, and it was an old (13 year) car, I was a bit cautious about changing it. Dextron 2 has always been fine. How much better is dextron 3, and how much extra does it cost?
The 'extreme conditions many manufacturers specify is a little vague. Haynes says this is stop/go urban, and my experience supports this. 15k really does make the oil go very dark red. It looks OK, but only when the new stuff comes out, does the bright redness of it surprise. What it would look like at 40-50k I can't imagine. At 100k it would be black, and probably full of abrasive particles. At this point the manufacturer has no obligation or liability, but to suggest a new gearbox.
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Sat 22 Oct 2005 18:47
Sealed for life auto gearboxes - Aprilia
Dexron III is a much superior formulation. It has a lower pour point and is thinner at low temps - giving better gearshift when your transmission is cold. Also it is more resistant to oxidation at high temps. I always put DIII in W124 transmissions.

No tranmission oil should be left longer than about 50k miles - even under light duty. It really does shear down - if you drain well-used oil it is quite thin c.f. new stuff.

The big enemy of ATF is temperature - that's that killer. Fit a cooler to make your transmission last longer.
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Sat 22 Oct 2005 23:07
Sealed for life auto gearboxes - Ruperts Trooper
I pay £9.99 for Dexron 3 although I'm not sure if it's 5 litres or 4.5 (1 gallon).
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