I have a 1971 1800E with the M40 transmission with electric O/D. The car has been running great recently, but the transmission is a little noisy (just a whine) and has been a bit more difficult to shift recently. She has an estimated 90K miles on her and no tansmission rebuild that I am aware of. The transmission has had a worn syncromesh going from 3rd to 4th as long as I've owned it. Not a huge deal if you let the engine rev down before engaging 4th. Tends to grind a bit going into 4th, but is fine once engaged. I have trained myself to use the clutch when going in and out of overdrive and it seems to be in good operating condition.

However, it's better to be safe than sorry...

I have decided that I should probably change the fluid in the tranny as I have no idea when it was done last (only owned the car about 6 months). However I have some questions and was hoping that I could find answers here.

What type of oil have you guys had good experience with? I was planning on going to a synthetic of some variety. The red Workshop manual that I have for that car states that I should use 30 weight motor oil. Would some 10W-30 Mobil 1 engine oil (which is what I use in the engine) work well in this case? I have also considered the Redline series of products that ipd sells because they have a synthetic designed for manual transmissions. However, the weight seems a bit high for this application (70W-80 GL-4 in this case).

Also, what kind of funnel do you use to get the oil in there with a minimal of mess? Looks like the fill plug is on the side of the trasmission.

Thanks ahead of time. I look forward to your always informative replies.
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1994 Volvo 940 n/a Wagon; 1971 Volvo 1800E;