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XC90 '02–'15 General Forum for the P2-platform XC90 model |
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Gear box oil change.Views : 3578 Replies : 41Users Viewing This Thread : |
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Dec 3rd, 2019, 18:22 | #41 | |
Bungling Amateur
Last Online: Today 10:46
Join Date: Aug 2014
Location: Beverley, East Yorks
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Quote:
1 - The old oil is so saturated with deposits that it will not absorb any more and hence debris accumulates in parts of the gearbox. When the fluid is changed, the new clean fluid penetrates the debris accumulations and loosens it in lumps which can lead to blockages and sticking valves. This can be mitigated by doing it in 3 or 4 partial changes (aka sump dumping) with a few hundred miles between them. 2 - The difference in viscosity between the oil and new fluid is so great, the gearbox electronics do not adapt quickly enough and an old fragile box is further damaged by shift shock etc. as it re-adapts. This can be mostly mitigated by clearing the adaptation memory or (even better) re-adapting the gearbox after changing the fluid. Where a gearbox is worn and has very old fluid, changing it can exacerbate certain faults due to the thinner fluid leaking through out of tolerance parts but this is really only a risk if the gearbox is knackered anyway. Even those owners with faulty gearboxes who change the fluid usually report noticeable improvement in spite of the underlying problems not being fixed.
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2011 XC90 D5 Executive 2003 C70 T5 GT 2012 Ford Ranger XL SC 1977 Triumph Spitfire 1500 1976 Massey Ferguson 135 |
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Dec 3rd, 2019, 19:15 | #42 | |
Me ? Surely Not!
Last Online: Apr 5th, 2024 16:23
Join Date: Jul 2010
Location: 2007 Volvo XC90 D5 Geartronic. South of Hadrians Wall.
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Quote:
I always do both of these when changing fluid. So far on both the 5 and 6 speed boxes, I've had no issues but always a definite improvement.
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“Do the right thing. It will gratify some people and astonish the rest.” – Mark Twain 😊 2007 Volvo XC90 D5 SE Geartronic |
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