Oil Analysis Results - 5000/170k mi

[SnowDrifter]

Figured I'd do a health check on my rig. Mainly just to poke at the casttech heads and see how those are. But also to see how my weird maintenance habits perform in the real world.

They came out pretty good, so, I figure I'll share my ways with y'all. Do with that what you will.
- Oil pump: Melling 295HV (oem pump had some cavitation wear, so in the f-it bucket it goes)
- Oil: Castrol 0w40 Euro Spec - preferred over 5w30 for various reasons. Numbers speak for themselves
- Filter: Fram XG3675 - synthetic media, 'long' filter. Included particle count. Someone smarter than me can discuss there
- Air filter: Standard mesh-backed dry filter. No oil wetted KN nonsense here.

General habits:
- PCV catch can is installed
- I drive my car soft until the oil comes up to temp. I took my hot oil pressure at 3k rpm and use that to self impose a 'redline' until it warms up to that point. In my configuration, that's 80 psi as per a digital readout. So, I cap my rpm/throttle to stay <=80psi as the thing warms up. Oil temperature lags quite a bit behind coolant temp!
- If the car has been sitting for more than a couple days, I'll crank the engine in 'flood clear' mode to get some oil before it starts up
- I don't idle to warm up. I drive gently. Once warm, I have no qualms about using the throttle
- I put a little TC-W3 rated 2 stroke oil in my fuel. 1oz/4gal. Roughly 500:1. Helps fuel economy a wee bit so, why not. Intuitively, might help with wear too.
- I generally don't turn the car off if I'm going to start it back up within a minute or 2 e.g. getting gas or grabbing mail

 

[Donal]

Thanks for posting your information and data. I am sure that many members and readers will respond. I have a bit of training, and experience in tribology and offer my interperation of your actions and analyses based on the analysis results and your narrative.
Cavitation is the result of negative suction pressure. The design of an engine where the oil pump is located above the oil level in the oil pan means that the pump is creating a void or increasing volume and atmospheric pressure is forcing the oil into the void. As the pump rotor rotates, the volume decreases and the oil is forced into the discharge port and into the oil flow path. So resistance to flow is important property here. Air entrainment can also contribute to cavitation. So the oil for these engines needs to have low resistance to flow under all conditions. So cold start up need mulit viscosity oil, like 0 W 30, 5 W 10, W 30 etc. The multi viscosity oil, have additives that allow the oil to maintain stable viscsioty as measured by labotory standards such as Saybolt seconds, centistokes, etc. so the engine has an oil that provides flow, reduces friction, prevents metal to metal contact, removes heat, and lubrication. Air entrainment causes cavitation wear and damage as the air bubbles form and then implode in the suction side of the pump.
This engine by design, operates in a negative suction pressure, and may air entrainment occur whenever the oring on the suction tube cannot prevent air from entering the system.
High volume oil pumps may have a negative impact on this engine unless internal clearences are increased. Otherwise the excessive oil pressure opens the system relief valve and oil exits the system and returns to the oil pan..

So, new and low wear engines, need the 0 W 30. As wear increases, a 5 W 30, later a 10 W 30 oil may the better choices.
The comment about the TAN number being 3.5, which means the oil is acidic. This is a slip up or miscommunication. Oil is not acidic or alakline since oil is not a water solution or mixture. The TAN number, 3.5, represents the alki metal additive package was converting the blow-by contaminates with water vapor to acidic sludge which the oil filter removes as the oil circulates thru the filter. The oil TBN (total base number,) is at its high value and the TAN (total acid number,) is at its low valvue in new oil and reverse values during the chemical reaction. Note that when an acid mixed with a base a salt is percipated.
The sample report show that the alki metals, calicum, phoprous and zinc still plentiful.

 

[gooffeyguy]

All the above gives me a headache, lol

My 2001 has 250k miles on it. I bought it in 2007 with 65k from my father in law who bought it new, so it's been in the family since day one. He always had the scheduled maintenance done on it, oil changed with Mobil1. Nothing more. I have done the same, when the "change engine oil" light on dash says to. No catch can, no special additives, no analysis. It's never had low oil pressure and has never had an oil leak until just recently wetness around the cooler block off plate above the filter. Fuel pump went out around 175k, and just in the past year had to replace water pump and alternator, but nothing else engine related. No special warm ups or drive cycles, just get in and go, like 98% of your typical owner of these vehicles.

Just my thoughts and experiences

 

[SnowDrifter]

Thanks for posting your information and data. I am sure that many members and readers will respond. I have a bit of training, and experience in tribology and offer my interperation of your actions and analyses based on the analysis results and your narrative.
Cavitation is the result of negative suction pressure. The design of an engine where the oil pump is located above the oil level in the oil pan means that the pump is creating a void or increasing volume and atmospheric pressure is forcing the oil into the void. As the pump rotor rotates, the volume decreases and the oil is forced into the discharge port and into the oil flow path. So resistance to flow is important property here. Air entrainment can also contribute to cavitation. So the oil for these engines needs to have low resistance to flow under all conditions. So cold start up need mulit viscosity oil, like 0 W 30, 5 W 10, W 30 etc. The multi viscosity oil, have additives that allow the oil to maintain stable viscsioty as measured by labotory standards such as Saybolt seconds, centistokes, etc. so the engine has an oil that provides flow, reduces friction, prevents metal to metal contact, removes heat, and lubrication. Air entrainment causes cavitation wear and damage as the air bubbles form and then implode in the suction side of the pump.
This engine by design, operates in a negative suction pressure, and may air entrainment occur whenever the oring on the suction tube cannot prevent air from entering the system.
High volume oil pumps may have a negative impact on this engine unless internal clearences are increased. Otherwise the excessive oil pressure opens the system relief valve and oil exits the system and returns to the oil pan..

So, new and low wear engines, need the 0 W 30. As wear increases, a 5 W 30, later a 10 W 30 oil may the better choices.
The comment about the TAN number being 3.5, which means the oil is acidic. This is a slip up or miscommunication. Oil is not acidic or alakline since oil is not a water solution. The TAN number, 3.5, represents the alki metal additive package was converting the blow-by contaminates with water vapor to acidic sludge which the oil filter removes as the oil circulates thru the filter. The oil TBN (total base number,) is at its high value and the TAN (total acid number,) is at its low valvue in new oil and reverse values during the chemical reaction. Note that when an acid mixed with a base a salt is percipated.
The sample report show that the alki metals, calicum, phoprous and zinc still plentiful.

Cavitation: I can only speculate as to why, given that I'm the second owner. I know the stock pumps are prone to cavitation at high RPM, but even with spirited driving - it's unlikely that these rigs see that RPM. Possible the o-ring was letting some air by, but the o-ring appeared in serviceable condition on teardown. Couldn't tell you the cause, only that it was. I think I still have the old pump gears laying around if you wanted to dig in.

High volume pumps: What negative impact?

Relief valve: The stock pumps are designed to operate with the relief valve opened too. That's why oil pressure is ~30psi at idle but it doesn't go linearly to 60 at 1200rpm. IIRC the stock bypass is supposed to open around 30psi, hence the nonlinear increase in oil pressure with RPM

Oil viscosity: I disagree here. Look at VI / viscosity over temperature. "30" is still the same viscosity at 100c. But the higher your VI, the less the viscosity changes with respect to temperature. Putting in a 10w30 that's thicker than a 0w30 below 100c, and thinner above 100c, as a function of engine wear doesn't really make sense. Older thoughts and technology said that you didn't want to use 0wXX due to shear down in the VII additive package. But that's not reflected in reality with modern synthetic products (see viscosity listed in the report).

TBN/TAN: I don't track. Non-aqueous compounds can absolutely be acidic / alkaline, no? It's just not measured directly as a function of H+ / OH- ion concentration (pH). Regardless: I have a personal disagreement with servicing oil by only measuring TBN. Serviceability of the additive package should be checked at the crossover point of TBN / TAN.