Oil consumption at 5500 miles on rebuild

[jerry598]

Almost too happy with the performance of my recent rebuild. I'm finally getting over the jitters about it blowing up and leaving me stranded by the side of the road. But, it still uses too much oil IMO.

I've driven it hard since the rebuild, trying to seat the rings. By hard, I mean, forget about fuel economy. I floor it as often as I can. Every hill is an opportunity to floor it and seat the rings. I vary the RPMs constantly. I never let it idle any more than a few minutes at a time. I've hauled several multi-ton loads of horse hay, stomping on it over and over to seat the rings. On different trips, I've hauled a couple of cars on a transport trailer and a 3 horse trialer with a 2500 lb. overhead camper in the bed, all in mountain driving, going full throttle wherever there was a long grade, again dropping back on the rpms and keeping them variable, usually between 2000 and 2800, back and forth.

But at 5500 miles now after my latest trip over the mountains it still uses about a quart of oil every 500 miles. Underneath there are no drips whatsoever. I love that part. No drips of any kind. Just a clean undercarriage. But will it ever stop burning oil??????????????

[JohnC]

I don't want to throw a wet blanket on things, but 99% of ring break-in occurs in the first half hour...

What was done to the cylinder walls? rings? ring gaps? What oil did you use to break it in?

[Kennedy]

I get a LOT of calls from guys looking for std bore pistons for a "rebuild" and I just don't get it. A proper rebuild will have you boring he cylinder walls straight and applying a proper surface finish to the cylinder walls to promote seating of the rings. This is far more critical than most believe.

[jerry598]

Darn,
Might have ruined it on the first start up. Got it running and let it idle about 15, maybe 20 minutes with no reving of the engine or rpms. Guess that might have been the ruin of it. It was very cold out at that time too. About 25 degrees farenhieght I think. Used standard 15-40 rotella dino oil. If so then it won't hurt a thing to change now to 5W-40 full synthetic for winter use, right?

[jerry598]

Cylinder walls were honed by the shop. Looked cross-hatched to me. She was bored .040 OS and they supplied the pistons to match in the box that said .040 OS. Checked the ring gap myself on installation. All seemed OK. And since the walls were bored oversize (supposedly .030 is the limit), then I should switch to full synthetic oil to limit wear on those thin cylinder walls. Damn, always missing something.

[twaddle]

What grade, type and spec of oil are you or have you been using on initial run in?

To high a spec of oil can sometimes cause some hassle.

Jim

[More Power]

In my experience, synthetic oil will produce about half the oil consumption when compared to a good petroleum-based oil like Chevron Delo 15W-40.

The few new or rebuilt engines I've broken-in were allowed to idle and put some heat on the temperature gauge after its first start. This involved 15-20 minutes for the 6.2/6.5 engines and nearly 45 minutes for the Duramax. Each of these engines produced less than typical oil consumption and became great engines. Our 6.5 project, for example, consumed about a quart or less of synthetic in 4,000 miles.

I ran all of these engines somewhat easy for the first 500 miles then changed the oil. I then ramped up the power slowly over the next 500 miles. At 1000 miles, I considered it broken-in, and changed the oil again. Oil changes were at routine intervals thereafter.

Jim

[DaveBr]

Just a thought - have you checked the CDR valve and the turbo to see if they are working properly?

[twaddle]

Hi Jim,
Do you use the fully synthetic oil during the initial start up and run in period?

I have always believed that if a rebuilt engine started to breath heavy or burn oil that if a more basic spec oil was used for a 1000 miles or so would help the components to 'bed in' then revert back to the higher spec oil.

I too am a great believer in the fully synthetic oil and have been using it for many years in everything from my 1942 WW2 jeep to my Diesel suburban with no ill effects to the older engines despite what a lot of folks were telling me.
I read an article in the Military vehicle preservation assoc mag a while back regarding the use of modern oils in classic/antique vehicles and the diesel spec fully synthetic had many of the additives that the old antique engine oils have.

Apoligies for diversifying a little bit.

Regards

Jim

[jerry598]

What grade, type and spec of oil are you or have you been using on initial run in?

To high a spec of oil can sometimes cause some hassle.

Jim

Initial run and break in was with Rotella 15W-40. Weather was definitely cold but engine was warmed up with block heater. Guess I should quit worrying about it and run it like its 100% broken in. Think I'll switch to Rotella T-6 full syn. and back off on the throttle. Backing off on the throttle might result in less oil consumption. We'll see.