Ji Andrew:
I thought that motor oil is only suggested for use where the year around temps are fairly warm (and it doesn't sound very warm where you are!) Double check your owner's manual.

I'm concerned about your use of Mobil 1, which is a "dexron" type atf. I think the M46 requires type F atf. I hope that you'll double check that with the owners manual.

If you want to use a sythetic atf, you need to get one with a type f rating. I think that amsoil makes one, and redline makes a synthetic atf that people use. If the guys who sell amsoil see this I'm sure that they will send you a note with info on the proper amsoil atf.

I've pasted in the section from the FAQs that deals with fluid for the m46. Hope this helps.

Mike Brown
1986 244 136K (m46)
1996 965 92K

From the FAQs:
M-46 Fluids and Fluid Change.
Fluid Type:

[Tip: Paul Seminara] The M46/M47 transmissions require Type F auto tranny fluid: NOT Dexron. It takes about 2.4 quarts if you can get it all out. I pumped in the new synthetic Type F (Amsoil Supershift Racing Transmission Fluid; product # ART.) . No wonder Volvo mandates type F. Shifts the best of any fluid I have tried. OD works flawlessly. [Editor: Redline MTL is also recommended.] According to Duane Hoberg, I should stick with a product without friction modifiers, and of the type directly recommended. [Duane] Your trans needs Type F ATF ONLY. Northern locations and winter eliminate the 30W oil option since you regularly get below the 10 C low point for the oil option. Dextron or Mercon ATF is NOT usable in manual transmissions not designed for that fluid. It does not have the resistance to "squeeze out" or the "cling" necessary to stay between the gears as they mesh. You will end up with metal on metal as you drive, increasing wear and heat. The heat will eventually deteriorate the fluid so it no longer lubes well. After that point is reached, the tranny will go down hill fast.