type of oil for hydraulic and transmission 1966 MF-165 (2024)

Trying to find out what oil to use in hydraulic and transmission of a 165 I purchased at auction.Right now it has a very thin oil like a universal hydraulic fluid. When running there is noise in the transmission and when shifting multipower from high to low it squeals. After the oil heats up there is excessive noise an the oil is thin.
The maintenance manual says to use M-1129 oil only available through the dealer. Called the dealer, says to use there perma lube which is a thin universal hydraulic fluid. Dealer did not find information on M-1129 oil
Please help, should this be a straight 90W oil like the MF50 use.
What is M-1129 Massey Ferguson oil?

M-1129 is Permtran III or 821XL. It is the only fluid recommended for our tractors. That being said...if it was a standard speed tranny I"d suggest an equivalent but with multipower I"d recommend the dealer fluid.

M-1129 is more like SAE 10-20 wt. Premium universal tractor hydraulic fluid made by Traveler @ Tractor Supply Co. is supposed to be a fluid equal to the M-1129 spec. I'm sure other brands will also cross reference to that spec as well, just check the label on the brand of your choice. If you haven't all ready, you should consider changing the filters. I bought a MF 180 with multipower / transmission that was reportedly shot, as in not moving at all. I do not know about the 165, but the 180 has a filter for the multipower ahead of the radiator. I changed that and now the multipower / transmission is working as it should. Know i need to change the filter on the hydraulic pump in the belly of the beast as they say. That looks to be a lot more complicated, service manual is a little shy in telling how to do it. Good luck with yours.

In the British Isles we only ever use 15W30 oil in our Masseys. Called Super Universal Tractor Oil or SUTO. It does what it says on the tin, in that it is Universal and can be used in engines and transmissions. I have been using it in our hard worked tractors for 40 years now without any problems. I am always hearing all sorts of oil recommendations on these sites, no-one in America seems to be able to agree what to put in their Masseys....We make life more simple.....Super Universal 15W30

I am now doing what SamN40 and JohnUK have been saying for ages. Modern motor oil. People have been going on about GL-1 and MF brand fluids... well, we aren't running IHC hytrans or cub cadets... and no one around me sells a pail with "GL-1" printed on it anymore. Supplanted by GL-4, but some people on these forums won't believe that either.
Local MF dealer lost franchise, so no proprietary brand fluids from there anymore either. So, 15W40 from TSC at $54 a 5 US gallon pail... and you can get a lot of useful things done with the empty pail!

Took your suggestion Christos and purchased the dealer oil Perm tran. Feel like I kinda got took on price as dealer asked how I wanted the oil, 5 gal. or 2 1/2 bottles.Told him I would take one 5 gal bucket and two 2 1/2 gal bottles. Dealer didn"t say anything about a difference in price.Got home looked at my bill paid 88 dollars for 5 gallon bucket 103 dollars for two 2 1/2 gal bottles. What a ripoff.