720 engine oil

[montidale]

I want to change the engine oil and fuel filters on a 720 diesel. The Tractor has been in the wifes family for as long as I can remember. The only oil
that they ever used on everything that ran was 15/40 Delvac or Rotela. The operators manual recommends 10/30 oil. Is there a consensus on what oil
to run in this Tractor? Also, the operators manual only recommends replacing the primary fuel filter. Only replacing the secondary filter during
overhaul. Seems to me I should replace them both at the same time. It looks to me looking at the parts manual that the primary and secondary fuel
filters are the same part number. Usually the secondary filter is different than the primary on most diesel engines. The engine was overhauled about
40 years ago, and I doubt if it has 200 hours on the rebuilt engine since then.

 

[Jim.ME]

(quoted from post at 07:06:34 10/18/23) I want to change the engine oil and fuel filters on a 720 diesel. The Tractor has been in the wifes family for as long as I can remember. The only oil
that they ever used on everything that ran was 15/40 Delvac or Rotela. The operators manual recommends 10/30 oil. Is there a consensus on what oil
to run in this Tractor? Also, the operators manual only recommends replacing the primary fuel filter. Only replacing the secondary filter during
overhaul. Seems to me I should replace them both at the same time. It looks to me looking at the parts manual that the primary and secondary fuel
filters are the same part number. Usually the secondary filter is different than the primary on most diesel engines. The engine was overhauled about
40 years ago, and I doubt if it has 200 hours on the rebuilt engine since then.

I would stay with the 15W/40 (which you post has been used in it for 40 years) unless it is now causing an issue. The 720 manual was written in 1956-1958, before 15W/40 was introduced. They don't go back and update old manuals to show use of products such as oils that changed/improved over the years. John Deere manuals showing 303 Special Purpose Oil are an example. 303 has been obsolete for years and has been superseded by several others to the current Hy Gard (J20C) product which is backwards compatible.

 

[NY 986]

If 15W40 has served reliably this far I would stick with it.

 

[rustred]

i dont think there was multigrade back then any how. it probably is to mean in cold weather use 10 wt and in summer use 30 wt. that is what most manuals called for. 15-40 is the correct oil for a diesel engine. 10-30 is not.as for the filters it is ok to leave the secondary filter go longer. all depending on the dirtyness of the primary one. plus check the ratings on the oil jugs.

 

[coonie minnie]

720s and 730s had a decal with the engine oil specs, or at least ours does. And yes, 10W30 was the primary recommended oil. 15W40 will be fine.

 

[montidale]

I decided it would be prudent to put both fuel filters in. Im surprised Tractor was running. decided to go with 15/40

 

[Scott 730]

(quoted from post at 10:54:31 10/18/23)

15-40 is the correct oil for a diesel engine. 10-30 is not..

Care to elaborate on that??