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Are the categories flagged consistent with a rebuild or abnormal wear?

My truck has 30,000 miles on a Fitzgerald glider rebuild with a Detroit series 60. The oil has 15,000 on it and is the third oil in the engine since the rebuild. Aluminum was flagged at 45. Tin was flagged at 7. Potassium was flagged at 121. Magnesium was flagged at 179. The lab suggested checking blow by and re-sampling at half interval. Is this normal for a recent rebuild? Should I change the oil again now and check for blow by or re-sample in 5,000-7,000 miles?

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All engines, rebuilds and new, the initial wear numbers could be all over the map. It usually takes a while for things to settle down. I never really start establishing trend lines on wear numbers and oil holding up till I pass 40,000 miles. I would just go as you are and take another sample at the next oil change. Magnesium, I wouldn't worry too much about. Many oils are starting to use higher levels of Magnesium as part of the add pack. Mine uses about 950 ppm of magnesium fresh out of the jug! Potassium combined with zinc in the additive package is the extreme pressure modifier that helps cams & rockers among other things. Some oils will use higher levels of potassium and even sodium in their additive packages.

Aluminum and tin are indeed wear metals, but because they are elevated in a newly rebuilt engine really doesn't mean much. Tin is used in bearings, but there is no real need for concern unless also getting elevated levels of lead and copper, which also make up rod and cam bearings.

The way to know what comes with the oil and what is coming from the engine is to have a new, virgin sample of the oil you are using tested so you can establish a base line and actually know if things are elevated when you send in a used oil sample. many folks fail to find out what their oil actually is made of. Otherwise, one is just guessing.

It is pretty early in the game on that rebuilt motor to start concerning yourself over excessive blowby. Let the motor settle in.

The Petroleum Quality Institute of America has done a lot of the leg work for us. They have tested a lot of name brand diesel oils and post the results of what they are made of on their site.

Here is a side by side comparison of several diesel oils done by PQIA:

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Thanks for your input. I was hoping this was the answer. What does your Detroit produce for turbo boost. I am happy with the power of my engine but would entertain buying a power box or bully dog if it would help. I normally am very near 80,000 and the aerodynamics of a carhauler are terrible so a little more boost might be nice.


Mine generally maxes out at 32 lb boost. I am not using a stock waste gate turbo, but instead a Borg Warner 171702 T6 non waste gate turbo. Much more efficient at typical road speeds.


24 is all mine produces, but it has plenty of power and the fuel mileage is great for a car hauler running the speeds I do. Bruce mentioned this was a Fitzgerald glitch when I spoke with him about it at Mats. Fitzgerald says this is normal. OPS called me yesterday and basically told me what you have about my sample. They also said that if I didn't want to have any issues with my engine warranty I probably need to change the oil at the Fitzgerald recommended intervals. They also said that Fitzgerald no longer offers the OPS as an option.


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Potassium has only one real major source when found in engine oil — antifreeze. You could resample after few thousand more miles. If it was mine I would probably change it but that's me.

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Thanks for your input Mel. This is a great site to access the valuable experience of others like you.


Potassium Tetraborate is being used more in some motor oils as a replacement for ZDDP (Zinc Dithiophosphate) as a load bearing agent. ZDDP has been found to mess with emissions systems, especially catalysts. So, depending on the oil, potassium can be part of the mix. Only if corresponding increases of sodium are present along with the potassium can one conclude it is coming from engine coolant. This is why it is essential to know what the oil you are using starts out with for an add pack. The old ideas and methodologies on what is what are rapidly falling behind the times.


Cliff send the article i've searched hi and low for potassium tetraborate in oil and nobody is using it. They all using ZDDP


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