I have an '83 B5100D with ~900 hrs. Runs great. Currently using what the book calls for (10 w40?) conventional oil. I prefer to run Mobil 1 in everything I care about. Can I run full synthetic oil in this engine? If so, should I get the one specifically for diesel engines? Thanks
Engine Oil Questions
- Thread starter BWXT
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Mobil has a diesel product line. The oil you choose must be rated for diesel engines, but you will not find the API rating that is specified in your 1983 manual. I believe cj-4 is backward compatible.
As far as synthetic is concerned that is perfectly fine.
As far as synthetic is concerned that is perfectly fine.
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Daren Todd
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Massey Ferguson 1825E, Kubota Z121S, Box blade, Rotary Cutter
You can run full synthetic in your tractor. Just make sure which ever oil you use. Make sure it's made for a diesel engine. 
Shell Makes a DIESEL Synthetic Rotella T in a blue bottle that I think is full synthetic.
My machine calls for Diesel spec'd oil Never conventional.
Something to do with the way the oil suspends the deposits.
I use 15W-40 year round. My machine is in a garage year around.
Some difficulty starting in colder weather but now let Glow plugs stay on for recommended 60 seconds. Also use compression release to spin engine before starting.
Others will be better able to help you
My machine calls for Diesel spec'd oil Never conventional.
Something to do with the way the oil suspends the deposits.
I use 15W-40 year round. My machine is in a garage year around.
Some difficulty starting in colder weather but now let Glow plugs stay on for recommended 60 seconds. Also use compression release to spin engine before starting.
Others will be better able to help you
85Hokie
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BX-25D ,PTB. Under Armor, '90&'92-B7100HST's, '06 BX1850 FEL
OK thanks. So, is it bad that I've been running regular old conventional motor oil and NOT diesel-specific oil? When I consulted the owner's manual it only specified the weight requirements. 10 w40 IIRC
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That is correct, what others have said: "Use oil specifically rated for diesel engines."
85Hokie
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BX-25D ,PTB. Under Armor, '90&'92-B7100HST's, '06 BX1850 FEL
Oils are like "paint" - different stuff in them depending on what your plans are when using.
Diesel oils have modifiers that "trap" the blow by particles that end up in the engine oil. Gas engines have blow by too, but different enough to have a different type of chemicals to help the trappings of those particles.
I would not say it is bad, just oils today do a much better job of keeping the engine running longer and cleaner, depending on WHAT engine and how that engine is used.
Thanks for the info all. I will change it out for Diesel full synthetic ASAP.
I have no idea. Got it from my father-in-law 3 months ago with the original trans fluid in it. LOL. Changed everything that can be changed per manual specs.
It's not a practice I'd recommend, but since it's an 80's tractor with 900 hours on it, if the oil was changed with any regularity, it will be fine. As previously mentioned, the differences for diesels is primarily in the detergents added to it, so if it's been changed every couple of years, the oil probably would only have 30-50 hours on it (assuming uniform usage) and would stay reasonably clean that way. Other than using the proper oil for it going forward, you can't really do anything about it anyway, so as long as it stays running good, I wouldn't worry about it.