My truck marks at the top line of the Safe zone at less than 12qts. Capacity listed in the owner's manual is 12qts. Which do I go by? 12qts regardless of the dipstick?

Probably sounds like a dumb question. I've seen this debate on this forum and others that it's 12qts "no more, no less". Others have this same issue about the dipstick marking vs oil in.

I recently saw the idea that maybe a leveling kit affects the level marking. I have no idea. I would just like to not put too much oil in. Seems logical, capacity is 12qts. But intellectually seeing the dipstick marking high, it makes me nervous.

 

I just changed my oil and with 12 quarts, the oil line only comes to the "e" of the safe line, I'll leave it like that and consider it full.

Only vehicle I've ever owned that seems like it is very difficult to get a good oil level reading.

 

Mine came from the factory with the oil level at the TOP of the plastic deal! I figured the factory had overfilled it,so I drained 1/2 qt. out of it.(Good luck with the all or nothing plug). This brought it to the top of the safe level. At my first oil change I prefilled the filter and dumped the balance of 12 qts into the filler. Same thing. We're right to the top of the plastic again. Although unnerving,that's my indexed full level. My '98.5 was right on the money.

 

I think in my manual you check the oil after it has been run to operating temp then let it sit for 15 minutes, I would think with the oil warm there is some expansion. If not add a little at a time to what it says on the stick, I dont think 1/2 quart here or there is going to hurt anything, you check the dip stick to make sure its not leaking out or using oil. just my .2c worth.

 

Shorts:
How much less than 12 qts does it take to reach the full mark?

My truck usually takes 12 qts & it's right on the mark after an oil change, but sometimes it will show way over the mark - then a day or 2 later it'll be back on the mark. My theory is that oil can get trapped up the dipstick tube - first time I went to pull a sample for oil analysis I couldn't get a small hose down through the tube into the sump & found out there's a seal or ring in the tube that only the dipstick can get by, so if any oil worked it's way into the tube it would give a false reading and it takes a long time to drain back out. Anyway it's just a theory - I can't come up with another reason why it would read high, then back to normal, etc. When I check mine right after shutting the engine off it almost always reads over the mark - then it's back on the mark after sitting over night.

Try checking yours each day for a week & see if it's always the same. If you've put 11+ qts in it seems there's no real danger to the engine, regardless of the dipstick reading.

A couple other thoughts - are you using the right filter? A smaller filter would reduce the capacity below 12 qts to get to full.

Are you getting a full 11+ qts out when it drains? Next change you could carefully collect & measure to make sure - don't forget to account for the oil in the filter (some oil stays in the filter medium so it never measures a full 12 qts). If 11+ qts isn't coming out (assuming it's full when you start the change) that would explain why it won't take 12 to refill to the mark.

You could send a sample for analysis to see if there's diesel in the oil - diluting it and making it read high - but it's probably not a factor right after a change when the engine hasn't been run much.

Find someone with the same engine who isn't having this problem and compare the two dipsticks, measure the tube - see if they're marked the same, tube is the same length, etc. I've read about dipsticks being mismarked or different between model years even tho the engine is the same (not saying it's a Cummins issue - just something to check out to try & explain the problem).

 

I've noticed that the dipstick is very finicky about the angle the truck is at. Whether it's loaded, or not, etc. Since the dipstick enters the engine behind the center line it will always read higher when the truck's rear is a little low &/or loaded.

 

I have noticed a discrepancy on many vehicles between the official capacity and the dipstick readings. While I don't think it's a huge deal either way, I will tend to sway toward underfilling slightly before overfilling. Also, on my own vehicle I will tend to use the official capacity, but on a customer vehicle I will tend to make it look right on the stick. I guess image is everything.

 

I go off the dipstick readings on any engine, and all engines have capacities.. IMHO the capacities are a guide..

You may get more or less out based on if you drain hot, cold, level, etc... And I would hate to overfill and do damage.

 

A little more info for me here. I'm ~4k into this oil change and my oil level hasn't changed. She's not making or losing oil. There was ~1/2qt left out of a gallon. I checked the oil cold. It was a lazy Saturday puttering in the garage so I checked fluids.

One of the recent threads got me to thinking about this again. Some guys are very adamant that its 12qts or you did it wrong. Since I'm one of those who's 'thinking with my dipstick' I just wanted to hear some discussion. Maybe I'm missing something, but maybe I'm not.

Bigwheel, thanks, that was just what I was wondering.

RDM, I don't recall how much I took to the oil dump exactly (I used a big bucket to catch before pouring into jugs). I'll note that this time around (got a Fumoto plug). My filter was only half full of oil when I pulled it.

 

I used to fuss over this problem as I noticed the same thing on my engine; sometimes a bit high and at other times at or slightly below the full mark. For about the last 80,000 miles I now just throw in three jugs of oil (12 qts) and forget it. A few days later when I check it cold the oil is right on the mark.
BTW, I always fill the filter before screwing it on.

 

It takes 3 gallons including the filter! Juggling quart bottles while checking the dipstick is really a waste of time.

 

Who's doing that?

 

I pre-fill the filter, dump the balance of the 12 quarts/3 gals in the engine. I also pre-fill my bypass filter, so whatever it needs is in the total quantity circulating. My dipstick reads about 2/3rd up the crosshatches when cold. Has been that way since new, continued to be that way after installing the bypass oil filter.

I have always gone by the mfr suggested capacity, never had any problems with the engine getting properly lubed.


CD

 

Guys that are getting a high reading on your dipstick try this next time. When you check your oil look at the top AND the bottom of the dipstick. For some reason the oil level reads high on the top of my dipstick, but it is not a good continuous reading. If you look at the bottom side you will see and nice continuous oil level and usually right where it should be if on level ground and warm after 15 minutes sitting.

 

My point is that trying to add small amounts of oil until the dipstick reads exactly on the full line is not needed. Fill the new oil filter and pour the remainder of the 3 gallons in the engine. Also, it is normal for the old oil filter to be only partially full when you remove it. This discussion of the oil capacity of a 5.9 CTD is a classic example of "over-thinking" a simple task.