Need replacement for Workhorse 8.1 L engine

ZDDP additives are snake oil and it's been literally proven over and over again. The only time zinc is "used" in motor oil is during cold start, when there is no oil circulating. Zinc bonds with metal and forms a protective barrier against impact. Once oil is circulating, oil performs that task. On any factory engine you can name, you only need minimal levels (like API specified) of zinc to provide this protection. On race engines, or seriously hot builds with extreme valve spring pressures and long duration cams, high levels of zinc are needed to protect parts during startup. You do not need anything more than ANY API-certified oil to break in any factory-build engine.

Review:

http://www.drivenracingoil.com/news/dro/training-center/articles/zinc-in-motor-oil/
http://synthetics.pennzoil.com/en_ca/high-performance-engines-extra-zinc-2/
http://blog.hemmings.com/index.php/2012/10/18/tech-101-zinc-in-oil-and-its-effects-on-older-engines/comment-page-1/

You will note that first link is from a company that *specializes* in high-zinc racing oil.

Very interesting:

http://www.ctci.org/gilsgarage/EngineOil2.php

(Note the oil analysis from "vintage high zinc oil."

SAE tech bulletin #770087 disagrees with GM.
Amsoil TSB # 2007-08-08 also disagrees and manufactures a break in oil with ZDDP added to their synthetic oil.
Removal of zinc and phosphorous are strictly to protect catalytic converters and please the EPA.
As I said in my post about ZDDP the original poster didn't need it as his cam and tappets are already broken in and may well be roller tappets anyway.
I do agree with the idea that most additives are snake oil. But not this one in regard to ZDDP and flat tappet break in. Even to the point of adding a bit to the oil every once in a while to recoat the cam and tappet interface. My knowledge of this is due to a rash of wiped out cams and tappets in rebuilt air-cooled VW engines during the early aughts, until some drag racers figured it out and let the gear heads know about it on this wonderful inter web thing.

Bill

While you are entitled to your opinion, doesn't make it fact. The facts of zinc in oils is there for a reason. Talk to any engine builder worth their weight  and see what they tell you. Flat tappet cams and lifters need these additives to survive, not just to break in. While some additives may be useless others are not. I've had enough engines apart both before and after using a particular additive and have seen major differences in both wear and cleanliness.

While the PO doesn't need the zinc type oils for the rings breaking in, regular dino oil will let the rings seat faster. Synthetic oil tends to be more slippery than regular oil. What did GM put in it from the factory?

driftless shifter said:

My knowledge of this is due to a rash of wiped out cams and tappets in rebuilt air-cooled VW engines during the early aughts, until some drag racers figured it out and let the gear heads know about it on this wonderful inter web thing.

Bill

Click to expand...

You may wish to review the links that I posted, especially given your experience in the early aughts. That *specific* scenario was addressed in one of them. For your convenience:

Back in August of 2005 (less than a year after API SM was introduced), the Society of Tribologists and Lubrication Engineers published a story stating that calcium-based detergents and dispersants competed against the ZDDP for surface space, and that caused some wear issues in passenger car engines. Around this same time many engine builders began to experience a rash of flat tappet cam failures during break-in.

Click to expand...

Those c2005 failures had nothing to with the quantity of ZDDP, but rather an increase in the amount of calcium-based additives that displaced zinc on the oil surface. Because engine builders aren't typically chemists, they assumed the reduction of zinc was responsible, which it wasn't. Switching to diesel oils with the "old balance" was one solution, adding mountains of zinc to revise the balance was another. The quantity of zinc is not and was not the concern. The balance of additives is and was.

But, hey, you do what you want. I would mention that SAE tech bulletin #770087 is from 1977, though. Maybe not the most current, and at no point does it suggest how much is enough - only that too little is bad. I don't know how anyone could extrapolate that information into a commentary about modern API certifications. The Amsoil TSB is nearly ten years old, and also offers absolutely no quantitative information about how zinc relates to valve tappet pressures, only indicating that cam to tappet contact is a point of wear. Call me cynical, but when a company selling a product says "Use our product or else" and offers no science to back it up I may just not buy into the ad - even if they call it a TSB.

92GA said:

While you are entitled to your opinion, doesn't make it fact. The facts of zinc in oils is there for a reason. Talk to any engine builder worth their weight  and see what they tell you. Flat tappet cams and lifters need these additives to survive, not just to break in. While some additives may be useless others are not. I've had enough engines apart both before and after using a particular additive and have seen major differences in both wear and cleanliness.

Click to expand...

I'm sorry, but zinc has nothing to do with cleanliness, and its only function is protection during startup, not while running. It's demonstrable on the molecular, chemical level as links I've posted show. You are of course entitled to believe what you'd like, but I would offer that if 800ppm zinc was an actual problem, every engine from small block Chevys to 4A Toyotas would have lunched numerous cams by now - *twenty years* after zinc was reduced to 800ppm by the API. Cam manufacturers would be the richest people on earth as every American who visits Jiffy Lube four times annually needed a new cam. They're not, because it's not actually a problem until valve trains are WAY beyond stock.

92GA said:

While the PO doesn't need the zinc type oils for the rings breaking in, regular dino oil will let the rings seat faster. Synthetic oil tends to be more slippery than regular oil. What did GM put in it from the factory?

Click to expand...

Every hi-po GM motor from the LS to the LNF has Mobil 1 full synthetic 5w-30 from the factory for over ten years now.

Their regular motors are conventional or maybe GM's standard semi-synthetic, just like Ford but I don't think those semi-synthetics were a thing until 2007 or 2008 or so. However, since both Ford and GM invariably supercede to whatever is new, you can bet that GM dexos semi-synthetic is what *every* GM motor not spec'd for Mobil 1 is supposed to be using since 2011.

Well the final (?) results.  Turns out the problem was a broken valve retaining clip that let the valve fall into the cylinder.  The cylinder didn't actually have a hole in it, just dents from the piston hitting the valve into the head that looked like a hole to the camera (see photo).  After checking and cleaning the heads, replacing the piston, valve, rocker, push rod and retraining clip (of course), the engine was reassembled, started and ran fine, except for a metallic knock that got more frequent when the engine was revved.  Conclusion was that the cam shaft had been damaged. 

This was the start of week two.  The front of the engine was torn down and the camshaft replaced.  It was scored as can be seen in the photo.  The rocker had also been flattened by the push rod (which should have been a clue to possible camshaft damage).  I wondered wonder why the oil testing didn't detect the cam shaft shavings since that is why we did it.

I then took the RV on a test drive of 1,027 miles.  It seemed to run fine, except for stumbling going up steep hills and when under heavy acceleration, which it had not been doing before (using three different tanks of fuel).  Also the gas mileage seems to have dropped at least 1 mpg (significant when you only get 8 mpg normally). 

At this point, I don't know what could cause the knocking stumbling and the reduced fuel mileage.  I'm going to take it back to the garage to see what they say.

For context, I had the repair done at Eagles Pride, which is inside The Great Outdoors RV Resort in Titusville Florida.  The real advantage is that they let me sleep in the RV inside their garage for the 10 nights, which eliminated the need to find other accommodation.

I'll keep you posted.

Wow, I am shocked they didn't find that cam damage during the inspection - if a valve retainer goes I would imagine you'd inspect everything that had contact with the valve.

The stumbling and loss of mileage is unfortunate - is it possible they got the cam reinstalled off a tooth? It seems from your post the stumbling was not present when the knocking from the cam was. Maybe you just didn't have any road time at that point?

Did the valve retainer actually break or did it just come out? I'm kinda of curious, as I like to find the root cause of things. Just at a quick glance, my thoughts are the camshaft lobe wiped out first and caused the rest of the damage.

Question, does the engine have roller tappets/lifters? If it has flat tappets it needs ZDDP content oil, regardless what the EPA says.

Bill

morefun said:

At this point, I don't know what could cause the knocking and the reduced fuel mileage.  I'm going to take it back to the garage to see what they say.

For context, I had the repair done at Eagles Pride, which is inside The Great Outdoors RV Resort in Titusville Florida.  The real advantage is that they let me sleep in the RV inside their garage for the 10 nights, which eliminated the need to find other accommodation.

I'll keep you posted.

Click to expand...

Reduced mileage and losing power is probably from the knock sensor detecting the metallic knock and retarding the timing.

kdbgoat said:

Did the valve retainer actually break or did it just come out? I'm kinda of curious, as I like to find the root cause of things. Just at a quick glance, my thoughts are the camshaft lobe wiped out first and caused the rest of the damage.

Click to expand...

That's what I see as well.

Won't even comment what I think about a mechanic putting an engine back together after a valve busts the top of a piston and not looking at the entire valve train at least for the problem valve....

The lifters do not have rollers.  The one for the problem valve was not bent, however the rocker was heavily scratched and quite worn, which I would have thought might have indicated a possible problem with the other end of the lifter (i.e. camshaft), but hindsight is 20/20.

The retaining clip for the problem valve was in pieces.  It had not fallen off.  This is what lead to the conclusion that it was the cause of the problem, so the front of the engine was not dismantled and the camshaft was not inspected before the initial re-assembly.  The engine was never taken out of the RV because we thought it was a simple problem, and they were trying to be kind to my pocket book (at $115/hr for labor).  At this point it is hard to say what actually started the problem.

The mechanic did say he had added something to the oil which might have been ZDDP, but I didn't ask.

Note that I made a mistake with my post, which I?ve since corrected.  The issue after the 1,000 mile drive was stumbling, not knocking.  I spoke to the mechanic and he thought the stumbling might be from a vacuum leak.  Apparently this engine has two vacuum systems and one comes into play under heavy loads.  Maybe that could affect the mileage too?

I'll let you know after they check for the vacuum leak, change the oil, and do another oil test.  Why didn't the original test show pieces from the Camshaft?  That is why we did it, and why they didn't completely dismantle the engine to check the camshaft initially.

I would bet you lost a lifter roller to begin with and that caused the rest of the damage. You did replace ALL the lifters too didn't you? I would replace the plug wires and have the timing rechecked to make sure it is set correctly. If he has too much initial timing, and it causes spark knock the ecm will pull timing to keep it from knocking. That will make it lazy.

You sure it doesn't have roller lifters?  Even the later 454s had roller lifters.

My 8.1L Chevy engine has a single under head camshaft that uses push rods and rockers.  I have attached a picture of this type of rocker, but I couldn't easily find a picture of the push rod.  The rod is a straight tube with rounded ends that had a hole in them.  I didn't see any sign of a roller anywhere, but maybe there is a separate ball that is dropped onto the camshaft before the push rod is inserted?

I don't know much about the timing on this engine, except I think it is completely computer controlled based on various sensors.  I did have my ScanGuage connected during my 1,027 mile test trip and it generally ran between 20-30 degrees under normal operation.  I was towing my car and when the stumbling occurred going up hills or accelerating quickly, the gauge dropped to 17 degrees then sometimes seemed go blank or drop to 1-3 degrees momentarily, which I think is a fault in the gauge rather than an indication of what the actual timing was doing.

All plugs and wires were replaced.

Here is what a roller lifter looks like.

Here is a flat tappet lifter.

morefun said:

The lifters do not have rollers.  The one for the problem valve was not bent, however the rocker was heavily scratched and quite worn, which I would have thought might have indicated a possible problem with the other end of the lifter (i.e. camshaft), but hindsight is 20/20.

The retaining clip for the problem valve was in pieces.  It had not fallen off.  This is what lead to the conclusion that it was the cause of the problem, so the front of the engine was not dismantled and the camshaft was not inspected before the initial re-assembly.  The engine was never taken out of the RV because we thought it was a simple problem, and they were trying to be kind to my pocket book (at $115/hr for labor).  At this point it is hard to say what actually started the problem.

The mechanic did say he had added something to the oil which might have been ZDDP, but I didn't ask.

Note that I made a mistake with my post, which I?ve since corrected.  The issue after the 1,000 mile drive was stumbling, not knocking.  I spoke to the mechanic and he thought the stumbling might be from a vacuum leak.  Apparently this engine has two vacuum systems and one comes into play under heavy loads.  Maybe that could affect the mileage too?

I'll let you know after they check for the vacuum leak, change the oil, and do another oil test.  Why didn't the original test show pieces from the Camshaft?  That is why we did it, and why they didn't completely dismantle the engine to check the camshaft initially.

Click to expand...

Well what is the latest? I think a vacume leak will cause stumbling. Who did the oil test?
Bill

The oil test was done by NAPA NA Parent in North Carolina.  They found a "light contamination of water" (not coolant - we think condensation) present and "other contaminant levels acceptable".  It makes me doubt the accuracy and usefulness of the tests.  Maybe they are only useful to determine the condition and life of the oil, and only marginally useful in determining the condition of the engine.

I'm taking the RV back in on Tuesday April 5th to check the vacuum, change the oil to synthetic and the filter, and maybe do another oil test.

I would use JG
http://www.jglubricantservices.com/
or Blackstone labs
http://www.blackstone-labs.com/
Oil analisis detects pending failure by mesering werer metals in the parts per million. it does not detect chunks from a sudden failure.
Look at the Blackstone site it has agood section on how to interput your sample results.
Bill