The mechanic put 75w-90 gear oil into the m47 on my 740 just yesterday.
Are there better alternatives? It seems the opinion is divided. Some recommend Type f/redline Mtl, some recommend gear oil and some even say to put 10w - 40 motor oil in?
Looking for the best option to preserve the gearbox and for the smoothest shifts.
I vote redline MTL for m47.
The factory filled M47 gearbox oil is a colour-less, odour-less, synthetic lifetime oil that should never be changed.
This oil is no longer available, it isn't made anymore and the superseded replacement isn't the same and is not as good. The owner's manual says Type F ATF, which of course isn't what the factory filled fluid was. I have witnessed myself (and others) inspect the fluid on 240's with M47 with over 200,000 kilometres and being 25 years old which I have known to never have had a gearbox oil change, and the fluid was still clear, no colour and no odour at all which at the time Volvo knew what they were doing when they said it was a lifetime fluid. Why the owner's manual does not say this remains a mystery to me.
I do not know why, but there is something in the guts of an M47 that is very oil-type sensitive and the wrong fluid can destroy one, whether it's the material of the synchro rings or something else.
I have heard the Fuchs Syntofluid gear oil is the equivalent, so now that your original unicorn fluid has gone, try the Fuchs. I have heard Redline MTL to be long lasting also.
Another thing with the M47, is to overfill the fluid by raising the left side of the vehicle. In the later M47's, named M47II, this is not necessary as the factory moved the fill plug higher up on the casing so as to allow more fluid in. If you don't, the 5th gear assembly runs dry and this leads to premature wear.
https://www.ebay.com.au/itm/Fuchs-Titan-Sintofluid-FE-SAE-75W-1-LT-pack-Manual-Gearbox-Spec/392844366216?hash=item5b77595188:g:WiAAAOSwwvtfLM65ramrodThe factory filled M47 gearbox oil is a colour-less, odour-less, synthetic lifetime oil that should never be changed.
This oil is no longer available, it isn't made anymore and the superseded replacement isn't the same and is not as good. The owner's manual says Type F ATF, which of course isn't what the factory filled fluid was. I have witnessed myself (and others) inspect the fluid on 240's with M47 with over 200,000 kilometres and being 25 years old which I have known to never have had a gearbox oil change, and the fluid was still clear, no colour and no odour at all which at the time Volvo knew what they were doing when they said it was a lifetime fluid. Why the owner's manual does not say this remains a mystery to me.
I do not know why, but there is something in the guts of an M47 that is very oil-type sensitive and the wrong fluid can destroy one, whether it's the material of the synchro rings or something else.
I have heard the Fuchs Syntofluid gear oil is the equivalent, so now that your original unicorn fluid has gone, try the Fuchs. I have heard Redline MTL to be long lasting also.
Another thing with the M47, is to overfill the fluid by raising the left side of the vehicle. In the later M47's, named M47II, this is not necessary as the factory moved the fill plug higher up on the casing so as to allow more fluid in. If you don't, the 5th gear assembly runs dry and this leads to premature wear.
Would this be it?
Also how do i know whether i've got a later model M47 or an earlier model? It came out of an 87 240
That's it.
If your M47 came from a 1987 model that would be the M47II type which was used when they deleted the speedometer cable drive from the rear of the housing and started using electronic speedometer (aka 1986 M46).
My 360 has covered over 850,000 km. The oil in the M47 gearbox has never been changed or topped up and is still clear. Only checked the level a few weeks ago and may be down a mm or so. Can't remember what the level was last time it was so long ago!
