M F 50 transmission / hydraulic fluid

I have just purchased a M F 50. The last owner said he used HD universal transmission / hydraulic fluid. Is this a problem? M F calls for 90 wt mineral oil
Thanks

Oils have come a long ways since the 50 was built, so you will get different answers on what oil to use. I use the HD universal trans/hydraulic oil with no ill effects. But as I always say just about any oil is better than forgetting to put oil back in which has been known to happen.

I have a TO35 1957 model and I replaced the transmission/hydraulic oil with napa 90 weight mineral oil, non detergent

my tractor has been used hard all these years and I am sure the hydraulic pump is worn,
in the summer months the lift works fine, but with the 90 weight mineral oil, in the winter months you have to set and wait a few minutes for the lift to start working

no real problem for me, as I have plenty of time and the motor needs to warm up a bit anyway in the winter, then the lift comes up.

i was very concerned about placing some type harsh cleaner in my hydraulic system, so i just got the tractor oil hot plowing, then drove straight to the barnyard and drained the oil, then refilled the sump, even then it took a good while for all the oil to drain out

does not really matter at this stage in the life of these old tractors, but i understand the 90 weight mineral oil was used as the transmissions in old tractors, like mine, have bronze bearings and some of the newer oils have harsh cleaning agents that can attack the bronze bearings.

also the mineral oil lets the dirt drop to the bottom of the sump where it is washed away as you drain the oil, the new detergent oils keep the dirt suspended, so it can go through the oil filter and be taken out.

if you use detergent oil in a tractor without a transmission oil filter, the dirt is circled through the hydraulic pump time and time again.

just my understanding of how the system works.

in England you can buy multi grade non detergent oil, but i never found any on this side of the pond.

note to file, pour your new oil in very slowly, it has to travel to three sumps and can fill up the first one fast, just take your time!!!!!!!!!!!

takes about 8 gals
i let it set overnight and checked the oil level again the next morning, just to be sure the oil had time to equalize in all sumps.

The last owner was correct...15W30 universal oil..................Sam

Active sulfur is what you don't want in a oil that is to be used with yellow metals. Oils with a EP (extreme pressure) additive contains active sulfur, the active sulfur "attacks" yellow metal. The main alloy in brass is copper with zinc, the main alloy in bronze is tin with copper. Don't use the 303 trans/hydraulic oil in anything older than a 1974 year model.

Thank you so much for the input but I'm
not able to find the Napa mineral oil are
you sure it was a Napa brand?

Tractor Supply, or Rural King usually has it.