97 Pontiac GTP L67 3800, GC 0w30 4.6k

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We still found signs of anti-freeze (see potassium & sodium) in the oil but level did come down. However, lead from bearings almost doubled and it may due to the coolant. Or, it may be from a particle streak through the bearings. If the latter is the case, lead will decline in the next sample. The oil's viscosity was a bit higher than normal for a 0W/30-grade, measuring closer to a 40W. We doubt it caused the higher-than-average lead. Air and oil filtration were normal and no gas was present in the
sample. Try ~5000 miles and check back for another look at lead.

Code:



OIL GC0w30 M5w30* M5w30* M5w30 M5w30EPM5w30 M10w30 M5w30 M10w30

MILES IN USE 4.6k 4.8k 5.5k 5.7k 5.6k 6.2k 8.7k 7k 5k Uni Avg

MILES 148.1k 143.5k 138.7k 133.2k 128k 121.9k 115.7k 107k 95k

SAMPLE TAKEN 7/21/07 4/7/07 1/6/07 9/2/06 5/7/06 1/7/06 8/21/05 2/28/05 6/6/04



ALUMINUM 3 4 3 2 2 3 2 2 2 3

CHROMIUM 1 1 1 0 1 1 1 1 1 1

IRON 17 24 19 14 16 22 18 17 13 14

COPPER 13 12 14 14 13 15 17 13 16 18

LEAD 19 10 14 28 11 23 42 5 5 7

TIN 0 0 0 1 0 0 1 2 1 1

MOLYBDENUM 18 91 84 82 72 85 77 60 70 41

NICKEL 1 1 2 0 0 1 0 0 1 0

MANGANESE 0 0 1 1 0 0 0 0 0 0

SILVER 0 0 0 0 0 0 0 0 0 0

TITANIUM 0 0 0 0 0 0 0 0 0 0

POTASSIUM 10 20 9 6 6 11 17 11 7 7

BORON 12 57 60 51 122 55 106 104 150 45

SILICON 9 11 11 11 11 12 9 9 11 11

SODIUM 24 46 20 6 9 10 14 12 19 11

CALCIUM 2013 2564 2308 2731 2294 2705 2780 2302 3134 2128

MAGNESIUM 424 20 15 14 19 19 19 25 23 131

PHOSPHORUS 797 737 658 673 698 677 745 592 831 741

ZINC 1041 932 818 834 870 838 946 694 983 901

BARIUM 0 0 0 0 0 0 0 0 0 0





INSOLUBLES 0.3 0.3 0.3 0.3 0.3 0.3 0.4 0.4 0.5

WATER 0 0 0 0 0 0 0 0.1 0

FLASHPOINT ºF 395 405 395 390 370 395 425 385 375

SUS VIS 210 ºF 67.7 63.6 64.4 63.2 62.5 61.8 65.3 63 62.2









*4qts M1 5w30 + 1qt M1EP 15w50






It seems that lead went up again even though the sodium and potassium levels are half what they were. I added GM coolant tabs to the system a few weeks after this oil went in since there was a trace of coolant in the last analysis. Since then I monitored the coolant with a dipstick type measuring device. Since this is the first run with GC I'll see how the next sample looks before taking action.

Comments welcome
 
Looks like the oils are all pretty equal. Only change is the coolent leak has slowed. Seems like your car is doing well considering the leak. I would monitor this coolent leak and continue with any of these oils. These oils are keeping your wear to a very minimum.
 
I wanted to add a couple comments.

In March of 07 I changed flushed the coolant with water several times and refilled with Dexcool. Shortly after we started to see signs of coolant, although no measurable amount was missing, so I added GM seal tabs ~3 weeks into this interval of 15 weeks.

Also all other analysis' have had 1/2 qt of makeup oil while the GC had none added to it. If this data was normalized it would bring down the GC numbers by ~10-15%. Since this is a new fill I expect the next interval to really tell the tale here. I still have trouble believing that lead is due to coolant since the 1st and 2nd analysis show such good leads numbers with pretty close Sodium and Potassium levels and I've never really had to add coolant to the car.

The engine is the blown verision of the 3800. Modifications include a smaller supercharger pully, cold air box and a reprogrammed computer of which all of these have been on the car for over 100k miles. In stock trim this engine puts out 240HP and 280lbs-ft. Driving pattern is pretty much the same as it's my commuter car seeing 55 miles a day M-F.

Quote:



I'd fix the problem if you care about the car.





I assume you mean the coolant leak?
 
Hi

Considering that the LIM gaskets are fairly easy to change out in the 3800, why not fix it and be done with the lead/coolant ?
 
Quote:


i have the same car...fun to drive..how does it run with the miles it has??




Pretty much the same as the day it rolled off the lot 10 years ago.
cheers.gif
 
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