Heavy diesel oil

deerefan · Dec 12, 2011

I have a 1968 4020 JD and run rotella 15w-40 in it. Is there a heavier oil i can get away with? The oil seems a little thin when changing. The motor seems strong, smokes until warm.

JESSE1 · Dec 12, 2011

Sounds like you're getting diesel in your oil. Might want to get an oil analysis. Your injection pump might be letting diesel leak into your oil system. What kind of oil change intervals are you doing? You might consider changing the oil more often.

Baby Grand · Dec 12, 2011

Generally, I would not change oil weight other than what's in the owner's manual. The reason I say this is that at some point, when designing a journal bearing, you choose an oil type. Clearances and other design criteria are then based on this selection, so unless you change the journal bearing design, you really need to stick with that oil.

deerefan · Dec 12, 2011

JESSE1 said:
Sounds like you're getting diesel in your oil. Might want to get an oil analysis. Your injection pump might be letting diesel leak into your oil system. What kind of oil change intervals are you doing? You might consider changing the oil more often.

I change oil 1x a year. I only put about 20 hrs a year on it.

devildog1 · Dec 12, 2011

I believe jesse1 is correct, the oil is not the issue, contamination of the oil may be.
Best way to confirm is as told, have sample tested, 15w-40w is a good weight for most diesel tractor engines. Good luck.
DevilDog

NIdaho · Dec 12, 2011

Your 15W-40 oil should pour like a 15 weight oil when it is cold (this is fairly thin) and then provide the protection of a 40 weight oil when it is hot. Did you warm up the oil before you changed it? Warming it up will make the 15 weight oil even seem thinner. Your oil is probably fine, but get an analysis and you might sleep better at night.

You do not want to go to a heavier oil ! Most wear happens during start-up. If you go to a thicker oil it will take longer to get distributed throughout the engine and you will increase the wear

.

Use the oil viscosity that is called out in the manual as believe it or not the motor engineers actually gave this some thought. By this I mean use an oil that the hot temperature viscosity is correct. If you want to go thinner on the cold temperature viscosity that is fine as it will flow thru the motor faster on start-up and you will have less wear:thumbsup:.

brucew44guns · Dec 12, 2011

Wasn't the last 4020's built around 1972? Your manual may well recommend a straight grade 30, I didn't attempt to research it on line as to what they said. But a 15-40 may well be a bit higher viscosity than what was originally advised to be used. If you have a leaky injector that puts enough oil in the sump to make it it appear "too thin" when you drain it, I would think it would be at least a little bit over the full line on your dip stick. The oil amount would have grown. Check it out if you changed oil, and take note of where it is on the stick, and check that level thereafter to see if it increases.

flyingcow · Dec 12, 2011

As mentioned do an oil analysis, and see where that takes you. I had early 70's MF's always used 15-40. But you need to be sure there is no diesel in the oil. The old rule of thumb is you should be able to smell diesel, or taste it in the oil. But the modern way is to send away a sample. Needs to have some hours on the oil for the test.

rsewill · Dec 14, 2011

flyingcow said:
The old rule of thumb is you should be able to smell diesel, or taste it in the oil

I wouldn't know what it tastes like. And lots of smells in oil. But I can feel it on a smooth part of the dip stick. If there is fuel in the oil you can pinch the stick between two fingers and it will not feel oily but more like there is no oil, just fuel. In other words, you can tell there is a lack of lubrication.