I have a 1990 Volvo B230FT powered with a ZF automatic. Shifting of the transmission is a but abrupt and the transmission seem to hunt between 3rd and OD. I figured a fluid replacement is in order. Is there any benefit to going synthetic? Or should I just drain, replace filter and cross fingers that shifting will improve. Thanks

I think that Volvo's procedure for automatic transmissions was to drain the pan and change the filter. This is a partial fluid change. I call it a slow fluid change.

On the 850 board, the new procedure for home mechanics is to do a slow fluid change - drop the fluid in the pan at every oil change until the fluid looks nice and clean.

I once had a full fluid flush by a dealer and in a week or so the fluid was a bit dirty. I complained and i was told that evidently the pan was not drained before the flush, so they did another proper flush.

If you change all the fluid drain the pan first off.

In my 60 years of working on my cars and talking to other owners, I have heard of several disasters when all the transmission fluid was changed. Even some stories on the 850 BB.

Quick question or two;
Have you checked the fluid level using the "process" while the engine is running? (shift slowly from P to 1, then back to P)
Will it shift to 4th if you let up a little on the throttle?

Either one of those might suggest that your trans is just low on fluid. My 740t would act as you described, when I finally changed the fluid and filter it was still glitter free.

Also, the harder I drove it, the smoother it shifted as it got past 4k.

I read the vin wrong the transmission is a AW 03-71 not a ZF. Good for me because I have read ZF transmissions are problematic. Dropped pan with fill tube attached. Cleaned pan, filter bright and shinny so it will stay. The pan contained minimal metal in the magnet. More of a grey thick material. Gasket in the way will refill with synthetic AT.

I read the vin wrong the transmission is a AW 03-71 not a ZF. Good for me because I have read ZF transmissions are problematic. Dropped pan with fill tube attached. Cleaned pan, filter bright and shinny so it will stay. The pan contained minimal metal in the magnet. More of a grey thick material. Gasket in the way will refill with synthetic AT.

a stock, original b230ft never had a zf installed. always aw71s.

change the filter and fluid and cross your fingers if you have no history of atf changes. should be every 30k. at some point volvo stopped changing filter on the aw trans, just drain and fill using the drain plug. to me, the filter is cheap insurance plus a pan inspection for glitter is nice.

Are you sure about the ZF transmissions? In North America, the AW7x trans were indeed the most common automatics coupled with the B230F, B230FT and B234F engines. In Europe, from what I can tell, the ZF transmission was more commonly associated with the B230E carbed engines and those weren't produced in North America, but may have been imported. Other information I've found suggests that some 740/760s may have had the ZF 22 transmission up until 1987 in North America, later in Europe. The ZF quickly became known as a troublesome transmission and many later got swapped for an AW. The turbo engines are harder on the transmission, so I imagine you may well be correct that Volvo avoided coupling the ZF with a B230FT, certainly by 1990. If the OP really does have a ZF, a more frequent change interval may be advisable.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

so correct me if Im wrong but half the fluid is in the torque converter not in the pan so if you change the pan you have just performed about half a transmission oil change, maybe 2/3.

in my 88 ford van I couldn't get that pan off. the bolts were all corroded so I gave up before having to fix stripped pan bolts. I knew if I continued I'd pull the bolt out along with the aluminum threads. maybe someone used loctite.

what I did then, was siphoned the fluid out of the dipstick with a small hose and refilled the same way , also removed the plug in the torque converter after gaining access by removing the aluminum brace thing under the bellhousing. I couldnt access the screen so I left well enough alone thare. I got some never sieze on the bolts and the stubborn ones might come loose if I try again this year. I ended up with oil that was maroon in color and refilled it. Not perfect but time was limited, and better than nothing. that pan has no plug to drin from , the volvo does.

siphoning takes time , so I just take a break and watch it until it stops. in manual transmissin cars I remember pumping from a can until my thumb was sore or running a hose out to the top of the car and rigging up a funnel on a hanging wire.

I think Volvos probably do have a drain plug on the torque converter but I don't recall ever removing one. I do recall taking apart a 140 and puled the engine then the torque converter fell out, maybe with some help, along with a gallon or two and it surprised me. I guess I had pulled the torque converter foreward with the engine removed, then sploosh !

Ive never actually flushed a transmission. maybe the easy way is to have a oil change place do it but Ive always been too cheap for that ;-) I'm not sure how much fluid you'd use to do it properly at home.

you might get a leak where the output shaft leaves the transmission to connect to the driveshaft. there is an oilseal and it's probably not that hard to change. my 740 leaks quite a bit so I have to keep picking different parking spaces to avoid being in trouble ;-) it seems to be getting worse so I could check the fluid and I need to look into changing that seal.

Forget having a shop use a hose down the fill tube to extract the old fluid. For our automatics, doing a drain followed by flushing the upper trans cooler line at the rad uses the transmission to pump fluid through the entire trans, changing gears a few times to open the channels. It's in the FAQ here. It's not at all a messy job and just requires a quick visit under the car to do an initial drain at the plug. You don't have to worry about getting every drop out. It uses 2-4 times the fluid depending on how dirty things are. If it's really bad, do it twice with some good driving in between. The brass flange on the plastic rad is sturdier than you might think and, along with a little penetrating oil, can be opened using a counterhold wrench (squeezed in your hand against the other wrench) with little fear of cracking the tank. Clear vinyl tubing (easily found in hardware/plumbing stores and sometimes available by the foot) and a few marked milk jugs is all you need. Once you do it the first time and realize it's almost as easy as an oil change, you'll want to do it more often.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

If you check the original Volvo owner service specifications, Volvo called for a trans fluid change at 22.5k mile intervals for the AW60 transmission. When the AW70 came along they stopped calling for the fluid change, rather saying to CHECK the transmission fluid every 20K miles. The published owner service manual only went up to 100k miles, so most assumed that to mean change the fluid at 100k mile intervals, which is what many of us try to do. When the AW71 came along, Volvo again changed the service interval to replace the fluid at 40K mile intervals. Believing these are fundamentally a similar internal design, I try to stick to a 60K mile interval (100k km) if done regularly, or else as needed if trans shifting behaviour becomes noticeably delayed. Trans shifting behaviour is also due to worn internal ball valve packs, so keeping them as clean as you can obviously helps, as does switching to synthetic.

Volvo used to specify trans filter element inspection and replacement at every change interval for the AW60, but stopped recommending that many years ago. Anytime I used to pull the filter it was always quite clean. The trans filter for those who may not know is a shallow fluid settling pan, not a particulate screen. It doesn't come with a magnet, but some later added one, as well as at the drain plug. It is easily cleaned, but for dealer service it was probably cheaper to simply replace it. It's a messy pain to drop the trans pan for access and I'm guessing Volvo thought it better to have the fluid changed more regularly rather than delaying service because it was a more expensive proposition labour-wise, hence going back to a 40K mile fluid-only change interval. Many of us happily drive our AW7x automatic transmissions for 100s of thousands of miles doing only regular flushing at the transmission cooler lines (as should be described in the FAQ) rather than simply draining the pan and refilling as is generally called for. Being able to keep flushing while running it through the gears has definite advantages and you keep flushing until the fluid runs clear.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Found a filter and gasket kit ay Rockauto. Ordered it in. We will see what happens with fresh fluid.

Synthetic ATF is highly recommended. I used Mobil 1 synthetic ATF in my 95 850 but that has a different transmission (transaxle). Make sure you get one that is compatible with an AW71. Flush first with the cheapest fluid you can find then refill with synthetic.
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Will I buy another Volvo??? We'll see....