2003 Cummins ISC 350 8.3 oil consumption

[Tom&Marie]

Any opinions as to what would be considered normal oil consumption for this engine with 65,000 miles over about 5,500 mles. It has used about 3 qts. The MH is a 2003 40' American Tradition pulling a Jeep Grand Cherokee

[ua40j]

I didn't read much about your engines history so I can only go by what you posted. Cummins has oil consumption published data that I've seen, but I can't find it. I recall that it was something like 1 quart for every 1000 miles. Very generous as I recall. I do know that there are too many factors that effect oil consumption. Type of oil, oil change interval, engine loading, etc.

I've attached two references. One is a Service bulletin from Cummins. It's a lot of data, but it also talks a little bit about how oil consumption is effected by your oil change interval. The example they use is an engine that burns 1 quart for every 2000 miles when subjected to a long oil change interval, can burn 1 quart every 500 miles.

The other reference is to a Valvoline reference where it discusses some of the other factors in oil consumption.

http://sbmar.com/Maintenance/PDF/Cum...tin_May-07.pdf

FAQ's :: Valvoline ::

In the end though, I don't think 3 quarts over 5000 miles is 'excessive'. I've got a call into my buddy at Cummins to find out more and will post it when/if I get it.

[nplenzick]

I've burned 3-4 quarts during my last oil change which was over 10K. My oil analysis suggested I cut back my oil change interval to around 8K. It also seemed that I did use more oil the longer I went. Right now I have about 3K on this change and I've added 1 quart. I also no longer fill the motor to the top mark on the dip stick. It seems it likes stay in between the full and add mark. If your concerned about your motor (or if your not) I would highly suggest an oil analysis. I use Blackstone Labs but there are others out there.

[GaryKD]

Hi Tom&Marie,
I have the 2005 330 HP version of the ISC. The engine has 57K miles. I burn no oil between changes (once a year). That being said, it took me a while to figure out how to do this. I always keep my oil at the mid point or higher on the dip stick. It would take <1K miles for the oil level to drop to the add mark on the dip stick. I left the oil level at that level and for several years it does not go below the add mark. I have heard some diesel engines are persnickety about the oil level, just never thought I had one.

Consider letting the oil level go to where it then stays. The engine may not burn oil at all.

[EngineerMike]

According to one of the more experienced Cummins guys, if you overfill, don't worry as the engine will take care of that for you by expelling the excess.

3 qts in 5500 is not high consumption overall. I'd want to know how it is using oil IIWM. To determine how much is blow-by, take a 1/2 gallon container, put some copper or stainless scrub sponge in the bottom, and tie it with the blow-by tube inside at the bottom nestled in the sponge fiber. Note your oil level and then watch the blow-by collector from time to time. Also watch for leaks. The rest is either leaking by the rings into the cylinders to be burned (shouldn't be much), or escaping into coolant which will show as a nasty slick in the coolant (shouldn't be any).

Always double check at every oil change you are getting the latest spec oil for diesel (CH-4 IIRC), and that the oil & filter is actually changed (see thread on Camping World for an eye opener on that).

Assuming you are getting mostly blow-by, you could try dropping your upper fill limit to see if it stabilizes better at a slightly lower dipstick reading (less blow-by). If that doesn't work, I'd go back to full fills, and if it does then there is your solution. You need to be meticulous about checking level with a lower fill limit, as you are eliminating safety factor of that upper gallon; you also need to accept shorter change intervals, tho w/yearly changes you probably are not reaching max mileage interval anyway.

[EngineerMike]

Oops, latest diesel oil formulation is CJ-4. Guess my memory was sleeping in when CI-4 sneeked by, and CJ slipped my mind when doing the above post. Hope nobody ran out & changed to CH-4 on accounta my blunder.

I should have made my statement more clear. I've seen places and met folks that will change oil using non-diesel motor oil (Mobil-1 so you get "full synthetic" e.g.). The acid fighting and soot dispersal components of diesel-specific oils are critical for long diesel engine life. I'd add gas engine motor oil to top off before a not-too-far-off-in-the-future oil change if I couldn't get Cx-4 type and was low. But I wouldn't change to non-diesel oil for any reason, and I'd check what the local shop is going to use if there is any question whatsoever. Better to wait a bit longer to change and get the proper additives in something that will set in the crankcase for a time and many miles.

[RustyJC]

In EngineerMike's example, those Mobil1 users who want the benefits of synthetics in their diesel should be looking at Mobil's Delvac1, the Mobil1 equivalent for diesel engines.

Rusty

[tom wilson]

if it does not go below the add mark, dont worry about it.