Castrol GTX 5W-20/GC 0W-30 mix; 3725 mi.; Ford F150 5.4L

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Jun 26, 2003
LA (Lower Alabama)
2000 Ford F150, 5.4L Initial fill 5 qts. Castrol GTX 5W-20 & 1 qt GC 0W-30 all from quart bottles. Should have been apx. 9.5-9.6 cSt @ 100ºC. Make-up oil ½ qt GC 0W-30 at apx. 3,000 miles into interval. 3,725 mile oil use interval. 66,030 miles on unit. Oil in use January 23, 2006 thru April 4, 2006. Mild weather. Temps averaged 40ºF to 60ºF with the occasional 30 or 70. 50%-60% highway miles.
		This		My 		Univ
		Report		Avg		Avg

Aluminum	2		3		3
Chromium	0		1		1
Iron		5		11		15
Copper		2		5		5
Lead		0		0		1
Tin		0		0		0
Molybdenum	33
Nickel		0		1		1
Manganese	0		1		1
Silver		0		0		0
Titanium	0		0		0
Potassium	1
Boron		10
Silicon		6
Sodium	        71 
Calcium	        1534
Magnesium	31
Phosphorus	607
Zinc		714
Barium		0
SUS @ 210ºF     55.6 (9.05 cSt @ 100ºC if my calculations are correct.)
Flash		395ºF
Fuel		<0.5
Antifreeze	?
Water		TR
Insolubles	0.3

Blackstone’s comments: The main changes in this analysis compared to the last are, the gas we found last sample has disappeared leaving the viscosity in the normal range for a 5W/20, and the sudden appearance of sodium. We strongly suspect the sodium is an additive from this Castrol product rather than from anti-freeze, which is the usual source for it. We did, however, turn up a trace of moisture in the oil. We will watch all this for you but you may want to use a different type oil next sample to watch the sodium. Wear read perfectly (again). The TBN was 2.1 vs 1.6 last sample. My comments: Don’t know what to think. Changed oil with 50% GTX 5W-20 and 50% GC 0W-30. (Wanted a bit higher viscosity for summer boat towing.) Was hoping to get a longer run on it but I don’t want to risk damage if I do have antifreeze problem. Searched and didn’t see any other GTX 5W-20 analyses, either virgin or used, with this much sodium. Anybody got any ideas?
Originally posted by doyall: Anybody got any ideas?
Pay Terry Dyson $10 and get him to interpret this for you. It's money well spent.
GC has transfused its magical essence into your run-of-the-mill 5w-20? [Wink] Seriously, I agree with the G-Man on this, check to see what Terry has to say. I would add that I think it's going to be hard to draw any solid conclusions unless you run a lengthy comparison study. It's not as if we have an abundance of data concerning GC+20 wt mixes. All the same, an intriguing result. Thanks for posting. [Cheers!]
Got an e-mail off to Terry to engage his services. Also sent Castrol an e-mail asking if they have started using something that might show up as sodium in their 5W-20 formulation. Anybody want to take a quess as to what their response will be, if I even get one. Strange, but other than the sodium this is the best of four UOA's that I have had done. Unless it is a really recent coolant incursion, would that suggest that whatever it might be is not abrasive?
E-mailed Castrol and asked if they used sodium, or something that would read as sodium in an oil analysis, in GTX 5W-20. Even though it took a while for a response, here it is:
Sodium is part of the additive package. It is used for detergency of oil. Its level varies according to additive supplier used. Each supplier uses different formulations for additive packages depending upon material availability
Very nice that they gave you a straight answer, a little one, but straight nevertheless. Now, I'd further conclude that the sodium must be a much more prominent part of the package in the 5w-20. I showed 8 ppm of sodium in my GC UOA (parallel thread), but only 1 ppm in the last GC UOA before. I had done an ARX cycle, mostly just for grins, and I suspect my 8 ppm came from the Mobil Clean 5k 5w-30 I used as a rinse phase oil. I don't suppose they commented upon your "mixology" did they? [Cheers!]
I don't suppose they commented upon your "mixology" did they? [Cheers!] [/QB]
Didn't tell them about it. Seemed to work enough well though.
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