XC70: Gearbox Worrying gearbox problem XC70

[RM955I]

What you're describing is exactly what a flush does: it empties the old crud and never allows the detergent to get to work so it's still stuck to the innards. A series of sump dumps (4 or 5 minimum) allows the detergent to get to work and for the clean fluid to absorb the contaminants. But what do I know....I only sold my P2 with 164k on it and the buyer remarked on how smooth the 'box was.

[pierremcalpine]

I'm having trouble with this theory. If you do a full flush you are ALSO REMOVING all the crud that is already in there. That has got to count for something. With a drain and fill you arguable have half the fluid in there that is already fully saturated with crud so the full volume is only half as effective in the use of detergent. Am I wrong?

[Cantankerous One]

Originally Posted by RM955I

What you're describing is exactly what a flush does: it empties the old crud and never allows the detergent to get to work so it's still stuck to the innards. A series of sump dumps (4 or 5 minimum) allows the detergent to get to work and for the clean fluid to absorb the contaminants. But what do I know....I only sold my P2 with 164k on it and the buyer remarked on how smooth the 'box was.

I agree with RM - having considered the pros and cons of both methods I opted for 6 sump dumps on my new to me 103k P3 leaving on average 500 miles between each one because that allows the detergents in the fluid time to do their work. By replacing approx 50% of the fluid each time you then end up with effectively 100% new fluid and hopefully no contaminants.
It's more expensive than a flush but, I believe, more effective.

[S60D5-185]

Originally Posted by Cantankerous One

I agree with RM - having considered the pros and cons of both methods I opted for 6 sump dumps on my new to me 103k P3 leaving on average 500 miles between each one because that allows the detergents in the fluid time to do their work. By replacing approx 50% of the fluid each time you then end up with effectively 100% new fluid and hopefully no contaminants.
It's more expensive than a flush but, I believe, more effective.

And me

A flush is nowhere near as effective as people think hence why if you check the gearbox fluid a short while after doing one it will be dirty not cherry red.

Luggsey's anology of emptying the dishwater is over simplistic and flawed. Don't take that as an insult Luggsey, it's just simply that we agree to disagree on this matter, and that's a healthy thing.
I am now in the process of doing a series of sump dumps and KNOW that when it eventually becomes cherry red on draining it, the next refill will keep it that way for many many miles and the WHOLE box will have been gently but more thoroughly cleansed than a flush could ever hope to achieve.

Ultimately it is down to the individual but how many people that have done a flush have later checked the fluid? Not many I would suspect.

I can see mine getting clearer each time I drain it so I know that this method is effective and it really doesn't take very long to do it.

[S60D5-185]

Originally Posted by pierremcalpine

I'm having trouble with this theory. If you do a full flush you are ALSO REMOVING all the crud that is already in there. That has got to count for something. With a drain and fill you arguable have half the fluid in there that is already fully saturated with crud so the full volume is only half as effective in the use of detergent. Am I wrong?

If you were to only do one drain and fill that theory would be absolutely correct but the drain and fill has to be done repeatedly every 500 -1000 miles until it eventually drains out clear. Time consuming but effective.

It stands to reason that every time you drain and fill, the remaining dirty fluid is again diluted by 50% with the fresh 3 litres and the detergent in each new refill becomes more effective .

[luggsey]

Originally Posted by S60D5-185

And me

A flush is nowhere near as effective as people think hence why if you check the gearbox fluid a short while after doing one it will be dirty not cherry red.

Luggsey's anology of emptying the dishwater is over simplistic and flawed. Don't take that as an insult Luggsey, it's just simply that we agree to disagree on this matter, and that's a healthy thing.
I am now in the process of doing a series of sump dumps and KNOW that when it eventually becomes cherry red on draining it, the next refill will keep it that way for many many miles and the WHOLE box will have been gently but more thoroughly cleansed than a flush could ever hope to achieve.

Ultimately it is down to the individual but how many people that have done a flush have later checked the fluid? Not many I would suspect.

I can see mine getting clearer each time I drain it so I know that this method is effective and it really doesn't take very long to do it.

It's one thing to say my analogy is flawed, it's another to convince me you are right and I am wrong?
What I have tried to describe is a compatible daily situation using detergent to clean things.
Detergents grab onto small particles and then suspend them in the medium they are in. If you add clean detergent to already dirty medium you will reduce the Detergents effectiveness because the Detergents will bond onto the crud already in suspension.
Try it with your dishes, use old dirty water and you get dirty dishes, use clean medium and get clean shiny dishes.
Saying the oil gets dirty again real quick simply proves it's working and cleaning well.
I keep asking the same question on here, who has damaged a good working auto box by changing the oil properly and correctly using the proper oil?
I haven't found anyone yet?

[S60D5-185]

Originally Posted by luggsey

It's one thing to say my analogy is flawed, it's another to convince me you are right and I am wrong?

That's my point Luggsey, I have no desire or interest in trying to try to prove you wrong or that I am right. We simply agree to disagree.

If you're happy to do things your way that's fine and it's certainly better than doing nothing.

[luggsey]

Originally Posted by S60D5-185

That's my point Luggsey, I have no desire or interest in trying to try to prove you wrong or that I am right. We simply agree to disagree.

If you're happy to do things your way that's fine and it's certainly better than doing nothing.

"Luggsey's anology of emptying the dishwater is over simplistic and flawed."

You just stated my analogy was flawed, that's saying I'm wrong in my book?

As you say we can agree to disagree but your comment is an argument that I'm wrong, that's not agreeing to disagree is it?

[RM955I]

As said repeatedly by a number of contributors, the problem with a flush is that it just passes clean fluid through the system until it comes out superficially clean. It never allows the detergent to churn its way through the box and go to work properly. What you're doing is like running a paint brush under the tap - the water may start to run clear but add a bit of detergent and give it a good scrub (like actually letting the fluid really work its way around the gearbox) and a load more paint will come out.

I think you are focused on the fact that it's not a complete change in one go rather than seeing it as a series of partial changes, each time allowing the detergent to work, churning through the gearbox, and each time further diluting the dirty fluid with clean until the volume of original fluid left is negligible. If you don't or won't accept that, well, that's fine.

[luggsey]

I think it's just different mindsets mate, I prefer to dump the old dirty minging oil that's full of crud and has lost its lubricating properties and detergent capability and replace it with brand new fresh oil which can go to work lubricating and cleaning much more efficiently then a mix of old and new oils. If it goes black after a few months it simply proves it's working?
I'm still waiting to hear about the good gearboxes that have been ruined by correct fluid changes as that seems to be one of the main reasons people shy away from a full fluid change?
Member Clan is a forty year veteran of Volvos and he maintains a full oil change is better then diluting old dirty oil with fresh, that was the opinion of the tech at my local dealers who is well into his three score years!