Can anyone tell me what weight oil should go in the rear diff for a '98 v70 AWD? All I've been able to find, is that it is different from the 75w-90 used in the bevel gear, and the Volvo part number for it. Also, is there a specific fill amount?

 

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CassMori, I found this at Volvoxc.[/align][/align]

I just changed my 6MT (M66) fluid, bevel gear, and rear differential fluids. I wanted to write down my experience so when and if you decide to tackle it you don't have to hunt for answers as much as I did. My car has 50K miles and I plan to keep it so the term "Lifetime fluid" means little to me. All of the fluids were dirty, in particular the rear differential. I would consider this mandatory maintenance if you plan to keep your car.
Transmission (M66-6MT): Easy to change, the tranny has a drain plug on the bottom, and a fill plug (23mm) on the side by the left front wheel (the wheel must be removed). Just drain out the old fluid, and refill. To refill you will either need an oil pump, to pump the oil in, or a funnel with a 24 inch long hose. I used the Volvo oil (part #1161745) for the M66, it is 75W-90 API GL-4 fully synthetic (Redline MT-90 should be a good equivalent). Fill until it starts to leak out of the fill hole. Capacity is 2.3L (mine only took 2L). Requires two aluminum crush washers (same size as engine oil drain plug).

Bevel Gear: Also easy to change, though it requires the use of an oil pump. I put the car onto ramps to allow easier access. The bevel gear only has a fill plug. Remove it, insert the small hose on your oil pump (make sure it is clean) and start pumping. Once you are done, pump a few squirts of fresh oil through the pump and into the waste oil container (to clear out the old fluid in the hoses of your oil pump, and ensure only fresh fluid will be used to fill the Bevel gear). Then pump the new fluid into the bevel gear until it begins to leak out of the fill plug. Install the plug. Capacity is .8L. I used Volvo AWD Fluid (API GL-5 BOT part #1161648). Requires one aluminum crush washer (same size as engine oil drain plug). (Note: bevel gear can also be filled with a funnel with a 24 inch hose). Volvo also has a procedure to drill a hole for a drain plug into the bevel gear's casing, it is unecessary, and will likely do more harm than good by introducing metal shavings into the unit, just use an oil pump, its easy.

Rear Differential: Requires the use of an oil pump. I put the car onto ramps to allow easier access. The rear differential only has a fill plug, it is located on the rear side of the differential and can be viewed from the area around the muffler. Remove it, insert the small hose of your oil pump (make sure it is clean) and start pumping. Once you are done, pump a few squirts of fresh oil through the pump and into the waste oil container (to clear out the old fluid in the hoses of your oil pump, and ensure only fresh fluid will be used to fill the rear diff). Then pump the new fluid into the rear diff until it begins to seap out of the fill plug. Install the plug. Capacity is .7L. I used Volvo Rear Axle Fluid (API GL-5 Low friction part #1161329). Requires one aluminum crush washer (same size as engine oil drain plug).

I recommend doing all of these fluids at once, just because they all require similar procedures and tools, this way you only have to mess with oil pumps and once and not on separate occasions. A few notable items: The fill plug on the tranny is very large (24mm). The rear differential requires a swivel with a 6" extension on your socket. Don't forget the crush washers, they are all the same size as the engine-oil drain plug. As for the oil, I would either use Volvo or another high quality synthetic like Redline. I should note that all of the Volvo fluids pour down to -48 degrees Celsius, which is described on the container of the bevel gear oil as being fully-synthetic. Otherwise the job is pretty straight forward.[/align][/align]Jagman Volvoxc.com[/align]

 

Thanks, Eric J, I don't know how I missed that! I had actually seen that, but did not register the part about the rear diff. Guess my eyes were a bit glazed over after all the searching I had been doing. Any idea of what the oil weight may be? Since it is listed as 'low friction', would it likely be the same as the MT oil & bevel gear oil, 75w-90, do you think?

 

I woulnt doubt if you could use plain old Valvoline 90w, but Volvos are Volvos..............Drive conservatively, Yuk Yuk