Chevy 6.5D engine question

I know this is not really tractor related, but there are a lot of knowledgeable guys on this board and I am sure there is someone that knows the answer to this question.

I put a new 6.5L diesel long block in my '95 Chevy pickup three years ago. There is now 31,000 miles on that engine. I have done some heavy pulling but most of the miles have been with the truck empty on paved and gravel roads. My question, do you think the engine is broke in by now, or will it need a few thousand more miles to do this?

I have had three new 6.5d and thought they were ready to go to work at 10,000 miles.

With modern machine work, it was probably ready to work at less then 1000 miles. I'm not sure what you think (or was told) has to break in? Years back, break-in was mostly due to imperfections in the bore-job on the cylinder walls that needed to the rings and wall to wear a bit to "break-in." Not much of an issue anymore if the engine was actually new - and not some some cheap patch job. Is the new block OEM or the newere heavier blocks now being made? When in complete engines they are called "Optimizer 6500s."

One funny note. My friend bought a new Chevy Duramax during the first couple of years. He had been spoiled with his Dodge-Cummins getting 20 MPG. The new $60,000 Chevy with Allison trans never got better then 14 MPG empty and he was furious. He kept going back to the dealer and kept getting told it would need at least 20,000 miles to "break-in" properly. The truck now has 170,000 miles on it and never improved a bit. What a suprise. His old rusty Dodge still gets 20 MPG empty.

By the way, I'm curious. Did you buy one of the new heavy-duty blocks that are made now? Much heavier then the originals. Heavier heads, heavier block with a stronger alloy, and optional forged-steel crank. I'd love to have one but they cost a small fortune.

I bought a new Dodge Ram with a Cummins Turbo Diesel in it. Tag on the cab said after 10-20,000 miles the fuel mileage will improve. It did, by 3-4mpg. I noticed when I bought my new S205 bobcat that compared to my old one with 4000hrs on it how much faster the motor stops on the brand new one when you turn the key off. If you use detergent motor oil it takes a lot longer to break in
IF break in periods are not needed any more then why does john deere still make break in oil.

Is the only part moving and doing work on your truck the engine? No wheel bearings? No ring and pinions? No transfer case? No driveshafts? No transmission? No wheel bearings? No brake calipers? Must be a very special truck you've got there.

I didn't say there is NO break-in period. I did say that with most companies using modern equipment, break-in time is MUCH shorter for engines because machining has greatly improved over the years.

About your Dodge truck. Do you really believe that the only component on your truck that had to break in was the engine? When your truck is moving, there are many other parts turning, e.g. axle gears, transmission gears, etc. There are many parts that might break-in a bit and turn easier.

If your Cummins engine got a 4 MPG improvement in 20,000 miles due to the engine alone - it sounds like it was put together pretty poorly - which I doubt.

About your degergent oil comments. Please explain to me what degergent additives in engine oil have to do with a prolonged break-in period? I think you've got anti-wear addtives (like boron, zinc, and phosphorus) confused with degergent additives.

You mentioned Deere, their break-in oil, along with your Dodge-Cummins truck.

Deere sells special "break-in" oil to promote wear on rings and cylinder walls to establish a wear pattern. Deere and other companies had many headaches with HD engines that had rings walk around the pistons and the gaps got lined up.

Other companies sell special "break-in" oil that does just the opposite and has extra ZDDP added.

When I worked as a Deere mechanic, we used high-degergent TorqGuard 10W oil for break-in as recommended by Deere Co. That until their newer TY22057 oil came out. Deere never told us to use a non-detergent oil for break-in. But, I have no idea of the specs on the newer oil. It may well be the old TorqueGuard 10W high-degergent with a new part #.

Why would a diesel pickup engine need a longer breakin period than a diesel farm tractor?

Just asking.

If your going to be an a$$hole, then do your own research. Your telling me that the bearings and drivetrain loosening up contributed to my extra mpg? They told me the breaking period was around 10,000 miles or more. Detergent oil wont let an engine break in. Dont ask me how but my neighbor only works on JD tractors. He overhauls more in a year than most do in a lifetime. He will tell you not to use detergent motor oil. Says the Deere break in oil is non detergent, but even the dealership cant tell me if it is or not. I have seen engines that have had to break in with detergent oil. Nothing seated like it should of. Torn it down due to excessive oil consumption, rebuilt it, used non detergent and everything was fine.

By the way, I'm curious. Did you buy one of the new heavy-duty blocks that are made now? Much heavier then the originals. Heavier heads, heavier block with a stronger alloy, and optional forged-steel crank. I'd love to have one but they cost a small fortune.

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No, I never even heard of that!

The long block I bought was a new OEM engine. The company I bought it from said they bought a bunch of new 6.5L diesel engines from GM, the engines were stored outside and got rusty, this company bought them and the went through them. It was expensive enough the way it was, I would hate to know what the new heavy duty engine costs!!

I was a Deere dealership mechanic for over 30 years, so I've got a little insight to what Deere has recommmended over a period of time. I first worked for a Deere dealer in 1966. Was your friend doing the same then?

As to you calling me childish names to prove your point? Have at it if it makes you feel better.

My point was, and still is - you have no way of knowing if fuel mileage might of improved over time due to other factors besides your engine. Many moving parts throughout a truck can "wear in" overtime and turn easier.

Also, about Deere. They usually use break-in oil for the first 100 engine hours - and that's the rough equivalent of 4000 miles.

GM stop making them quite some time ago. For awhile, Navastar was casting the new blocks.

Since our military needs a constant source for 6.5s (for the Humvees), and also the marine industry, somebody starting making the Optimizer 6500 blocks. It's just a very beefed up 6.5 that costs a small fortune. As far as I know, that is the only new 6.5 being made.

You also cannot prove that other parts of my truck breaking in contributed to my fuel mileage increase. Oh and I am sure they are still building tractors the same way 20 years ago. I think someday you will know it all.lol

I didn't think anyone used nondetergent oil anymore. I have rebuilt a few engines and I used detergent oil. I have never had a problem with oil consumption.

A 6.5 with a steel crank would fix one of the main issues with the engine. Add timing gears and it would be a decent engine.

I don't have to prove anything, but some facts are well known, and easily verifiable.

You don't seem to know what you are talking about.

#1 Your comments about degergent oil are wrong. Seems you've got anti-wear additives confused with degergent additives. Granted, many people assume that non-degergent oils are "old fashioned" and therefore don't have those anti-wear additives. But, that was only true for automtotive oils made before 1950.
A "pure mineral oil" is the oil without the wear additives. A true break-in oil that is made to promote some wear IS pure mineral oil - not specifically non-degergent. A true break-in oil made to prevent wear is the opposite and has extra ZDDP added. GM sells it, as to many aftermarket camshaft companies.

About John Deere and the way they build engines? The way they do it has changed radically since the late 80s. They made big changes in their machining processes and tolerances when the 50 series came out. So did all the car/truck companies. Again, you speak with little knowledge.

You also seem to have a reading-comprehension problem since you claimed that I said there is "no break in" anymore. The fact is, I never said that. I just said it's a shorter period.

I remember many new engines in the 60s, that were high-compression, that would use oil and smoke until you hammered then and drove them for 5000-10,000 miles. That was due to imperfections in cylinder walls and a few other things.

If your Cummins 5.9 diesel was so crudely put together, that fuel mileage was as poor as you claim early on - it would also of skipped at cold start, smoked, and used oil. I doubt you had that problem - but if you did, you had a lemon.

And as I already said, a truck when moving has many metal and rubber parts causing friction. They too can "wear in" and turn easier over time.
For a reason that escapes me, you choose NOT to believe that, yet you are eager to believe that takes place inside the engine. That is, unless you think the entire problem is cylinder-wall and compression related. If so, you're back to an oil-eating, smoking, skipping diesel engine.

I don't think the steel crank would help much in any 6.2s or 6.5s made by GM. It is sometimes hard to tell what fails first, but it seems that most of the blown-up 6.5s with broken cranks go like this. The main-bearing webs in the block develop cracks. Overtime they get bigger and longer. Finally, a main-cap literally breaks off, leaves the crank unsupported, and the crank breaks into several pieces. I've got several such engines laying in my junkpile.

I've pulled the pan off many good running 6.2s and 6.5s with 200K miles plus on them - and ALL had cracks on the main webs. There is an aftermarket studp-girdle kit available - but I doubt it really helps.

With the very last 6.5s that GM built, they attempted to better the failure rate by making the outside bolts on the main-caps smaller. Went from 12 mm down to 10 mm. With the smaller outside bolts, more metal was left intact in the block.

The new 6.5 engines available with forged steel cranks have much heavier blocks. Also use a much higher nickel-content alloy.

Non-degergent oil and oil with no zinc and phosphorus additives is still needed in some older tractors. Especially with wet brakes that can get ruined with modern oil. If sold as "motor oil" is has to be rated as "pure mineral oil." Easier to get it in a can called "transmission oil." 90W GL-1 transmission oil is basically the same thing as 40W non-degergent, no-addtive motor oil.

Tractor Supply also sells standard non-degergent 30W and 40W motor oil. It has all the anti-wear additives but no degergent additives. I use it in old tractors if they are all sludged up inside and I don't want to know any of it loose. If I rebuild an engine, and clean it up inside - then I use modern degergent oil afterwards.

I never said that you claimed there is no break in period needed. If I did, show me. And I never said my dodge got poor fuel mileage, just that fuel mileage improved from around 16-20-mpg. Who has the reading comprehension problem? I never said that I didnt believe you but you offer no proof that the fuel mileage came from other parts in my truck breaking in. Honestly if a ring and pinion wore in enough to provide a gain in fuel mileage than it would probably wear out real fast.And by the way if I want engine knowledge I will ask my Dad. He was rebuilding engines while you were still wet behind the ears and still does. You say that you use to work as a Deere mechanic... I use to write repair manuals for John Deere and here is a fact my boss use to tell me- When you write a manual you are writing it for someone with an 8th grade education.LOL. Post back if you want to but I wont even look this far back to read it.

You said you gained 3-4 MPG after your very-long break in period. The word "poor" was used by me as a relative term. If you gained 4 MPG , then you lost 4 MPG as you go back to when your engine was new. I call a loss of 4 MPG poor and a huge loss. You may call it whatever you like.

You wrote manuals yet don't know the difference between non-degergent oil and oil with no anti-wear additives?

By the way, if I was "wet behind the ears" when your friend was rebuilding engines, I assume he's over 80 years old now? If so, and he's still working as a full-time mechanic for hire -he either has a lousy job - or really loves working for other people. Or maybe wants to get away from his wife?

Tell me more about your 80 year-old mechanic friend who rebuilds high numbers of engines every year. I want his secret for good health and longevity.

Actually, some manufacturers are claiming that with their tighter machining tolerances today they don't require a break-in period.

Cummins claims that if you pull the plunger from the injector from a new heavy-duty engines, draw a line around it with a dry erase marker, and try to put it together, you will fail. The ink from the marker will be thicker than the clearance.

Ring and pinions do wear into each other some. Basically they are smoothing out the contact areas. Unless they aren't set up properly. I've read in truck magazines that tires need to break in, too, that they can get better fuel mileage once they wear some.

Yes, I'm aware of all that an agree 100%. Some people however choose to not believe such things. And, get angry when anybody dare mentions them. Maybe now the angry-guy can start calling you childish names instead of me. Gets tiring and can ruin an otherwise good posting.

With heavy duty engines however, many companies advise a slight break-in period since they are built to be used hard and steady - unlike passenger vehicles. When we sold new tractors, we would not let them leave the dealerhip until we ran on a dyno for a full day with mixed loads. I can't say what we did helped or not, but can say we tried -and followed Deere's orders. We were afraid either somebody would take home a brand new tractor and stick it on a PTO full-load - or bring it home and baby it too much. Who knows? Maybe that would of been better? Deere told us to use mixed loads at first, and not steady.

Back around 1968, I bought a factory-rebuilt 389 engine for my 1965 GTO. That thing smoked something awful for a long time. Very long break-in period - I assume because it was so sloppily machined and put together. I doubt anybody could get away with selling stuff like that anymore.
That was the last and only rebuilt engine I ever bought. I now do myself, or just buy a good used engine that nobody's been into.

With John Deere . . . their engines reached a quality-control low-point with the 40 series ag. tractors and C series crawlers. After that there was a big shake-up and Deere engines got put together much better.

Break in would likely be slower for the pickup engine compared to the same engine in a tractor, dut to the fact that Average engine load for the pickup is to run it at 30-50% power while the average farm tractor averages in the 80% load range.

Also I suspect JD is right in that their is as much break in friction lost in the rest of the driveline as there is in the engine. Parts get smoother, initial bearing preload relaxes and brake rotors and pads smooth out.

If you check the link below, you will see that Cummins forbids non detergent oil in your pickups 5.9 engine, they want you to use an diesel spec 15-40 multi viscosity oil and expressly forbid use of any special break in oil.
Cummins 5.9 oil spec.