2003 Volvo S80 2.9 Question for transmission fluid flush

[anno]

For this 2003 S80 (with 88,000 miles), there is a loud click every time I making a shift, while no impact on driving so far. I'm thinking to flush the transmission, by repeating drain/fill through the cooler hose as I researched online. Is there any risk for doing so? It seems that it is still running with the original fluid, not sure whether a flush would ruin the system (valve/filter etc.), considering the high mileage.

Another question is for the ATF to be used. Probably two kinds of fluid (3309 or Dex III/VI) were used for S80 series, and I just have no idea which one applies to my car. By the way, what is the difference between Dex III and VI?

Could anyone help clarify? Really appreciate your time.

[majorcode]

Before flush, check the oil condition if it is red you can flush, if it is brown or near black forget to change flush, because you won't able to drive as you are driving now.

Yes it is DEX III /VI. Dex VI is more better than Dex III and usable.

[anno]

Thanks majorcode! The fluid is actually dirty as told by mechanic during last maintenance. Can I simply drain and fill to exchange the fluid gradually? Maybe 3.5 quarts every 10k miles?

While that means different fluid (original and new) will be mixed together. Don't know whether Valvoline Maxlife dex/merc or Catrol Transmax dexron VI will be compatible to genuine volvo one? These are the ones available in Autozone/Advanced Auto nearby.

Could you guys give some comment? Thank you very much.

[kahl]

hi Anno, I had the Volvo dealer flush my new transmition after 38K . the color before flush was tan/brown. They hooked car up to a machine that cycled a cleaner fluid through transmition then drained out old fluid and pumped in new fluid. the cost was $225.00 for this service. there was no changing of the filter.
majorcode has a point about flushing a high mileage transmition. I do not consider 88K a high mileage number. Though you are close. Myself being paranoid of these transmitions I would consult with a Experienced Volvo tech and get his opinion for your particular car.

[SimLyons]

Hey Anno: Good questions. Dex III was made to GM specs. The S-80 early models (incl. yours) use a GM transmission, thus the spec for usng Dex III. GM quit the spec years ago but since there are millions of those transmissions out there the ATF guys saw a chance to sell a lot of ATF. The specs were improved and currently Dex VI has replaced/supplemented Dex III. There is no Dex III spec valid anymore. Use Dex VI.

My S-80 lost it's transmission at 48K miles. It was replaced and at 60K more, the fluid smelled burned and was brown. I did a total drain and flush and filter replacement. If I were to do it again I'd use the gradual drain (2-3 qts). Ny new trans is showing early signs of problems so I'm really taking it easy. Will see in a few months.

Wish you the best!

[SimLyons]

Some folks say Dex III is still available. It isn't, at least according to GM, who licensed it to begin with. See the following piece from Wikipedia (credit where due). If you buy Dex III there is no spec behind it that is legal. It could be anything.

"The fluid specification for Dexron-VI was introduced in 2005, and was first used as the GM factory-fill automatic transmission fluid for model year 2006. All Dexron-III licenses expired permanently at the end of 2006, and GM now supports only Dexron-VI fluids for use in their automatic transmissions,[3] although fluids asserted by their manufacturers to meet Dexron-III standards continue to be sold under names such as Dex/Merc. These fluids are not regulated or endorsed by GM.[4]
Dexron VI is of a slightly lower viscosity when new compared to the prior Dexron fluids (a maximum of 6.4 cSt at 100°C for Dexron VI and 7.5 cSt for Dexron III), but the allowed viscosity loss from shearing of the ATF during use is lower for Dexron VI, resulting in the same lowest allowed final viscosity for both Dexron III and VI (5.5 cSt).[5] The lower viscosity is intended to gain improvements in fuel economy by lessening parasitic drag in the transmission. Since Dexron VI is not allowed to thin out (lower its viscosity) as much as Dexron III during use, it requires the use of higher-quality, more shear-stable (less prone to thin ess in use) base oils.

[anno]

Hi, majorcode, kahl, SimLyons,

Thank you so much for your suggestion. I will go with some DEX VI compatible auto transmission fluid, like a full synthetic one. Considering the car is old, the problems (if emerge after the flush) might be just a matter of sooner or later, right?

Let you guys know the result once I'm done (probably no filter change this time).

[anno]

Hi, guys,

lacking of tools to properly jack-up the car high enough, I get it flushed by professionals for peace of mind. Using valvoline maxlife ATF, along with BG transmission flush kit, the shift is now doing great. The acceleration seems to be weaker. I'm not sure whether this is what majorcode means, but it's totally fine since I'm a slow driver.

Thanks again for your comment.

[majorcode]

Hi Anno, Valvoline maxlife ATF was DEX III or simple DEX, because it does matter, Like if it is Dex only then you have no other solution and have to put Dex III which was specified otherwise sooner or later you really ended up with transmission failure.

OR

Keep driving at least 300 to 600 Miles, if you still feel the weak acceleration then time for DEX III or DEX VI specially Castrol one because Volvo and Castrol love each other and in my experience it works good too.

Good Luck!

[matt5112]

Changing the fluid isn't going to fix the fact that your clutches are likely worn.

Also I strongly suggest an upgraded valve body with any 4T65E rebuild. Otherwise your replacement won't last any longer than the original did.