Oil Analysis - I need advice

2000 Montana

I changed my intake manifold gasket in February '06 because it had visible external leaks, I was losing coolant, and my oil analysis from Blackstone Labs said that I had coolant and fuel in my oil. At the same time, I changed plugs, wires, hoses, belt, etc. We like the van and we want to keep it as long as possible. The engine runs like brand new.

However, my oil analysis reports are still showing coolant in the oil, even though I'm not losing a significant amount of coolant. I've topped off the coolant once in the last year, adding about a pint.

I've had the oil checked four times in the last year. Sample "A" was before the intake gasket replacement. Sample "B" was after I had driven with the new gaskets for 1,276 miles, just to get some wear on the oil, clean things out and get a good sample. Sample "C" was 1,862 miles later because sample "B" didn't look good. Things seemed to be trending in the right direction, so I figured all was well. Lately, I've been smelling coolant around the van when it is warm, so I had Sample "D" done at 93,982 miles. Here are the numbers:

...........................A............B......... ...C..............D....
Date.................2/5/06.....4/1/06.....5/7/06.....11/10/06
Odometer..........84,271.....85,556.....87,418.... ....93,982
Miles on oil..........1,145......1,276.......1,862......... 4,550
Potassium*.............93.........156...........81 ............116
Sodium**.............110.........259..........123. ...........251
* Potassium universal average should be about 6.
** Sodium universal average should be about 10.

(Please excuse the extra spaces in my table. Not sure why they're there.)

The most recent sample showed no water in the oil.

Here is what Blackstone Labs said in their comments:
"Your sense of smell didn't betray you. 0.50% of the sample was anti-freeze as indicated by the amount of potassium and sodium that were present in this oil sample. The high insolubles (.6%) contained the contaminants. Wear metals looked okay compared to universal averages (which are based on a 4300-mile oil change interval) for this type of V-6. It appears the recently installed intake gasket may not be working properly or the coolant might be leaking into the oil due to a worn out head gasket. Try a cooling system pressure check again and use short oil changes."

Blackstone was kind enough to actually call and talk to me about this, and they were very puzzled by the fact that I'm not losing coolant. They were also puzzled by the fact that the van runs perfectly smooth...no smoke, no hesitation, no stalling. You could sit a full glass of water on the top of the engine and not spill it.

Note the extreme differences in mileage on my samples.

I haven't done a pressure test yet, but I'd like to do one this weekend. I'll borrow the tester from AutoZone and see what I can find out. I've never done one before, so I hope I can figure it out. If anyone wants to give me advice for specifically what to look for (besides obvious leaks) I would appreciate it.

Random thoughts:

- I haven't had fuel in the oil since the intake manifold gasket change.
- I was concerned right after the gasket change with the numbers going the wrong direction, but I assumed it was all the caramelly stuff being cleaned away. When the third sample came back significantly lower, I assumed things were fixed.
- Blackstone said that the coolant in my oil problem hasn't affected engine wear. All the metals (aluminum, iron, lead, etc.) are below the averages.
- I thought I had the coolant smell narrowed down to the overflow container. There's supposed to be a black plastic thing on top (I think it's where the hood rests) that is broken off and it has left a hole in the top of the coolant reservoir. As the coolant sloshes around, that little area is sometimes wet with coolant. I was going to check on replacing the reservoir or getting that little black plastic piece replaced.
- If this is the head gasket, I'm in over my head. What would be a reasonable price for an independent mechanic to replace the head gasket? Should I have that done, or should I just trade in the van for something else?
- If I change the oil every 3,000 miles and test every few months for engine wear, is there anything terrible that can happen?

Thanks for reading all of this. I would appreciate any advice you can give me.

It is possible that some degree of residual coolant is trapped somewhere in the cylinder head or block and is not being eliminated during the oil drain event, this may cause some transfer of the coolant properties into the oil, without a tear down no way to know. If you are sure you are not intermixing in any way and not loosing coolant you should monitor this as you have. It would be interesting if there are other analysis results available for comparison, where intake gaskets were done as a result of heavy intermix, maybe Blackstone has the info.

A quick update. I borrowed the pressure tester from AutoZone today, and the results were sort of inconclusive. I think the pressure tester had a slow leak. I tested the cooling system, and the needle went down very slowly. I tested my cap, and the needle went down very slowly. I hooked it back up to the radiator, pumped it up and called my wife out (who has better ears than I do). She listened for a leak and found one...on the pressure tester.

So, I'm sure I don't have a major leak, and relatively sure that it held pressure.

Does that help anyone?

There are test strips available at parts houses, Napa, Carquest, to check for exhaust gases in the coolant, this may reveal something, but not all gasket leaks reach the cooling system in this way.

I need to add one more detail here. I'm pretty sure I figured out the source of the coolant smell. The water pump had started "weeping" just enough to throw out droplets, but not enough to be really obvious. I figured that out the other day when I looked up and saw a stripe of coolant on the hood insulation just above the serpentine belt. I replaced the water pump last night, rinsed everything off really well and took it for a drive to get everything good and hot. No more coolant smell.

So, now I just have to figure out what's up with the sodium and potassium in my oil. I'm really starting to lean toward leftovers from the bad intake manifold gasket. I'm going to change the oil after about 1,000 miles this time and go for another test. I'm going to see if I can get it all cleaned out over time. Oil changes are cheap and easy.