90 weight alternatives.

I am in need of changing rear end fluid in my 8n, in our area I cannot find the recommended 90 weight mineral oil. What is a good alternative? Thanks

This is one of the best posts from the archives on hydraulic oil. SAE 90 is not the best oil to use especially in cold weather. The consensus is a Premium UTF is the #1 choice.


A decade or so later oil formulation had progressed considerably and Ford introduced a new all season tractor oil (M2C-134D) that replaced the older oils and was recommended for year round use in just about all of their common sump tractors. So how does that match up with the current day products you listed?

A number of the products on the list are pure hydraulic oils. They lack the level of EP additives needed for wear protection of the transmission and final drive gears in your tractor. They are identified by the labeling as Anti-wear (AW) hydraulic fluids and/or a grade designation of AW xx or ISO xx. They are intended for use in dedicated hydraulic systems and should not be used in a common sump tractor application.
The products labeled as Tractor Transmission/Hydraulic Fluids (UTF) are multi-function fluids designed specifically for common sump applications like the N-series tractors and are a generic equivalent of the Ford M2C-134D oil. They have a robust EP additive package for final drive and transmission wear protection and a high viscosity index making them suitable for all season use in a hydraulic system. As such they closely match the performance characteristics of the seasonal oils originally recommended by Ford and eliminate the need for changing oil with the seasons. I would suggest you stick with them and as previously mentioned avoid the ones labeled as J20A or 303 oil. They are inferior oils matching a long obsolete John Deere specification and are not suitable for year round use in cold climates. And unless you live in an extremely cold climate I would avoid products labeled as J20D compliant. This is a modern low viscosity version of the J20C product and intended for use in more modern equipment that are very sensitive to cold weather increases in viscosity (e.g. hydrostatic/CVT/power shift transmissions, power steering, wet clutches/brakes, etc).
Not listed is a modern SAE 80W90 gear oil. This is a multi-grade version of EP gear oil that will perform a bit better as an all season oil than the originally recommended gear oils but not as well as the UTF products.

Premium UTF's generally have a measured viscosity of ~9.5 cSt @100C and ~55 cSt @ 40C. That puts them somewhere between an ISO 46/68 hydraulic oil, on the low end of an SAE 30 engine oil, and smack in the middle of an SAE 80 gear oil. That is one of the reasons they are excellent oils for use in common sump tractors.

Shown is the all mineral SAE 90 GL1 gear oil. This is a conventional gear oil that contains no EP additives and has an extremely low viscosity index making it inferior to just about all of the others in terms of wear protection and cold weather performance. I put it in the same category as the 303 oils.

There are a lot of products to choose from but the simplest and most economical choice for year round use is any Premium UTF that Rural King or TSC has in stock/on sale.





All that being said, pictured are two SAE GL1 oils that I have used in lieu of the FORD MC134-D oil and never had problems with them and I live in mid-Michigan where it gets cold.

CNH FORD MC-134D HYDRAULUIC OIL; NLA:

Tim Daley(MI)

I cannot find the recommended 90 weight mineral oil.

The owners manual was written in 1939. Just like with engine oil, much has changed for the better in petroleum products in the past 80+ years. The original
recommendation was NOT for 90w mineral oil; it was EP Gear Oil conforming to Ford specification M-4864-A and B, SAE 80 below +32 degrees F, and SAE 90 above +32
degrees F. (Do you want to change your hydraulic fluid every spring and fall? ) However, the new recommendation from the local Ford-New Holland dealer now
recommends Ambra Multi-G 134 (NH-410B) synthetic fluid. CNH sells a product called Ambra 134D that conforms to that specification. The equivalent product (and
less expensive) from TSC that meets Ford spec M2C-134d is their Universal Tractor Fluid. Neither of these products are SAE 90 gear oil - they are multi-purpose
oils with an exceptionally high viscosity index engineered specifically for this type of application.

Any UTF that meets the Ford spec M2C134D will work fine in your N tractor. Just read the label on the container.

I use the UTF from TSC year around here in VA.

You will find the UTF to work a lot better below 32* F than 80/90 w oil.


See tips 3 & 4

Do NOT overfill it. If you overfill it, the excess will leak past the wheel seals and get on your brakes.

Unless the sump is totally clean, a dry sump will only take about 4.5 gallons. Remove the lower bolt on the inspection plate, add 4.5 gallons and come back an
hour or so later to see if it is dripping. Remember, it takes a long time for that oil to get back there.
75 Tips

Thank you Tim and Bruce for the reply. I have read allot of different opinions over the last couple days but Having been on this site for years I know I can trust you guys. This tractor when done will be going south of KC so it won't see the really cold weather and probably will only see use in Spring, Summer and Fall. I did find the Premium UTF at O'reillies yesterday, I might have to go back and snag that before it's gone too. Thanks gentlemen.