When do you need to change the ATF oil?

Can I check the oil itself somehow or symptoms which indicate an oil flush is needed?

 

There's no factory service interval for the ATF - but most will agree on a refresh from time to time. There seems to be two camps - the 50K miles and the 100K miles clubs. I'm in the 100K club which means about once every 5-7 years. Personally I think 50K is overkill unless you regularly drive mountains or tow a trailer long distances. Newer cars are coming with full synthetic fluids which have very low contaminents (google bobistheoil for research articles) and holds up better than the stuff in your mom's Buick :-) The most common symptoms will be sluggish shifting or hard shifting but that may not be fluid related at all. The way to check the fluid is by smell, color and whether any debris (ie clutch bits...) is in the fluid. On models with a dipstick, its as easy as wiping the dipstick on a white paper towel (plenty of youtube vids on what to look for) - reddish brown is good, black/burnt smell is bad (and the damage has already been done). On models without a dipstick you'd need to open the drain plug - which if you've gone that far, you might as well drain it all out and fill it back up.

As to the fluid change, there's two methods. Most DIYers use a drain fill method. Draining the fluid gets about 60% of the fluid out so you drain out 4 quarts or so, refill, run the car to circulate/mix then repeat. After about 3 cycles you are around 90% fresh and good to go for another 100K. The second method is to open the transmission cooler lines and put hoses into two buckets (shops have machines to manage this) one for the pumped out fluid, one to pull in the fresh. When the fluid out looks new its done. Both will require about 12 quarts of the correct fluid type for your transmission (not all Volvos use the same ATF, ie some may be Dex III, some may be JWS 3309. Final step is to make sure the transmission has the correct level, which is measured on a warm transmission. Shops will use VIDA or a similar tool to have the transmission temp sensor to know when the its reached 55C or you need to follow a driving cycle to approximate that temp. If you have a dipstick, there's a warm temp level on it to measure with. If not, the transmission has a dual bolt drain where the center bolt opens to a drain tube (full is determined by the height of the drain tube) and the outer bolt removes the tube to allow the tranny to fully drain.

So with all that long winded info, I'd simply say have a shop do a refresh at 100K miles (many dealers will offer this as a special) unless your car is acting up with hard shifting, flares etc where you should take it in for service by a pro.

PS - my comments are assuming you have an automatic and not a dual clutch electronic manual like VW/Audi's DSG. Those transmissions do have a service interval (40K for the VAGs) so when in doubt, check the factory maintenance intervals your your model

https://volvornt.harte-hanks.com/man...int_Charts.pdf