Too much oil can be bad too?

You have a DD15 so you have two options.

Your dipstick from E to F is 1 gallon. So you can wait until it's close to E and add a gallon, which is what I do since I carry oil in gallon jugs.

If you carry oil in quart size bottles, then I would add a bottle every time it drops to 3/4.

 

It would take more than a gallon probably, but the crank hitting the oil, like many have stated, causes foaming and then the oil pump pickup and bearings may be starved of lubricant.

Also, causes hp loss, as that crank hitting oil is a huge drag.

Some engines use what is called a windage tray" below the crank to try and stop the contact.

 

Hmmm if enough thick cool oil got by seats I think you would be burning gallons a hour ..

 

The engine can be burning oil which is why it may have had oil added in the first place.Not gallons per hour though.

 

Same here. Since I own my own truck I buy the oil. I watch my level go down slowly but steadily between oil changes and by the time I'm close to a change it might be halfway down the safe level. I avoid putting more in because I know I'm going to change it soon. No need to waste oil on a truck putting a gallon or even a half gallon in when it holds 10 gallons. It isn't going to hurt the truck.

Our mechanics at my old company used to start complaining when drivers would let them get 4 or 5 gallons low and those old Freightshakers kept on pulling.

 

. I had a injector selinoid crack, and put 10 gallons of fuel into the oil. I knew the injector was bad, and tried to make it home. Never crossed my mind it could be leaking fuel. By the time it shut down, oil/fuel was leaking from every seal. After I changed the injector, I changed the oil. I couldn’t believe how much fuel it had in it. Had no choice, but to put about half of it in the fuel tank, nowhere else to put it. Bottom line, aside from a seeping front crank seal, didn’t hurt a thing. Engine lasted another 300k, hit 1.3 mil. before it was inframed. Like the time my breather tube got blocked with ice, it shut down and oil was pouring out of every seal. Pop the hood, and think, Oh this is bad!! Lol.

 

The C12 was done. Bearings right down to the copper. It was probably running at least 2 or 3 days with diluted oil.

 

Today's engines are tighter.

The older engines had an open crankcase breather tube. R model Macks liked to be 1/2 gal down.

I remember the drivers gathering around a new fueler to inform him that it wasn't necessary to add that 1/2 gal every night as they were good and tired of smelling it as it blew out the breather and burned off every morning...

 

Tighter? How so? My 41 year old CAT on its 3rd rebuild with original block/crank, never ground/line bored and is still 0.005" to 0.0065" clearance on the rods and mains.

Not going to get much tighter than that.

 

internal clearance has nothing to do with external crankcase venting...

and your crank was probably forged on a Wednesday.