1997 Tahoe Castrol 5w30 and Auto RX for 1,700 miles

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Chris B.

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My Tahoe has 102,000 miles on it now. I bought it used and as far as I kniw it was born and raised on Castrol GTX. I did an Auto RX to clean things up and chack for internal problems. Here are the results.

5.7 V8
102,000 tatal miles
Auto RX flush for last 1,700 miles on Castrol GTX 5w30 and a SuperTeck oil filter.

Aluminum 3

Chromium 1

Iron 8

Copper 4

Lead 13

Tin 1

Molybedenum 14

Nickel 0

Manganese 0

Potassium 25

Boron 3

Silicon 9

Sodium 18

Calcium 2060

Magnesium 0

Pohsphorus 682

Zinc 837

SUS viscosity @210F 60.7

Flashpoint 410

Fuel 0

Antifreeze ????

Water 0

Insolubles 0.7


I can't beleve Black Stone did not put down if antifreeze was found in the oil!!! I really wanted to know as I know older engines can have this problem. I'll have to call them and have them chack for it.

This is the 1st time I used Auto RX and I don't know how it effected the results. They don't look to bad to me but can you experts help me interpret this report? Thank you!!
 
It doesn't look catastrophic, but lead is up in such a short interval. I'd say it is an intake gasket issue. I just don't even know what to say anymore with these GMs. My Dad's 4.3L Blazer has already had it fixed once and is consuming coolent faster than it did before.
dunno.gif


Does it consume coolent or show signs of moisture on the oil cap? I'd for sure get it checked out and mention this analysis. Good luck.
cool.gif
 
SO far it does not appear to be consuming coolent and I don't see any on the driveway. The Potassium could be the coolent, right? Could it come from the Auto RX and I also added a can of BG fuel injecter cleaner(acctually my shop did as a "free" bonut to a tune up I got. I use FP and not BG stuff) Could it have come from the BG?
 
Potassium @ 25 is nothing to snuff at, IMHO. Just wait unti it hits the 3-digit range before you shall consider raising the alarm RE: coolant problems.
 
quote:
Originally posted by Quest:
Potassium @ 25 is nothing to snuff at, IMHO. Just wait unti it hits the 3-digit range before you shall consider raising the alarm RE: coolant problems.
Click to expand...
Why do you say that? I'm new to this kind of problem and I want this engine to be ok for another 200,000 miles.
 
No offense Chris but we are talking about ppm here (parts per million). 25 ppm of Potassium can be attributed to oil additives if memory serves.

As another satisfied ARx user don't we all want to make our engine last longer?

q.
 
Is this the AutoRX flush oil?

If it isn't, and with readings like these, I'd seriously consider getting a professional read from Terry .

1700 miles
Lead 13
Potassium 25
Sodium 18
Antifreeze ?
Insolubles 0.7

From an amateur point of view, I suspect a coolant leak.
 
This was the oil that has the Auto RX in it for the cleaning phase. This is not the rince cycle yet as that is what is in the engine now. I think that is why the oil is so dirty.

I'm having Terry look at this and he is helping me greatly! I just thought I'd share and see what you guys thought.

Coolent scares the heak out of me!
frown.gif
dunno.gif
 
Chris I would replace the intake gasket now if you haven't done it yet. My '96 5.7L has about the same numbers of miles on it and I went through near the same thing you are. I was getting potassium in the oil but no antifreeze was detected yet, but I know it was just a matter of time. I had an external coolant leak on mine but it only made it to the ground once every couple weeks. When I had mine replace the mech said the gaskets looked like they were getting ready to fail and allow coolant into the oil.
My brother has 2 of these 5.7s and had to replace the intake gaskets on both. One showed some pretty high wear via UOA before the problem was fixed. The UOA said no antifreeze detected but you could see it was in there.
I'd have it fixed on your schedule, and then do a rinse oci before you put in any expensive oil.
Here is several UOAs on my 5.7L. Some after the intake gasket and some before. Also from what I understand high lead and good numbers elsewhere means you might benifit from a thicker oil. Does yours have the oil cooler/tow package?
 
OffOrWFO thanks for the info!

I have the tow package but I think I only have a transmission cooler.

I plan on getting rid of Castrol GTX as I see to much eveidence it is not the best dino oil. I'm going to try GC and see if the thicker oil helps.

First I'm going to watch the coolent tank to see if it drops at all. I have it Exactly on the line and if it drops I know I have an intrenal leak.
 
quote:
Originally posted by Drew99GT:
Anywhere from $500-$800. I'd have it done at a reputable shop though or by someone you know.
Click to expand...
The price is mostly labor so if you have a good mechanic in the family you can offset most of the cost in Pizza and Beer.

You might check around and see who has the best replacement design.

Fel-Pro, Victor, GM. Shop by design not price.

However I would run Auto-Rx rinse phase and then run one more OCI and then have a UOA run before jumping to conclusions. Especially if you have no external evidence its leaking ie coolant use or leak. If it is leaking its not critical at this point.

Gene
 
Thank you guys I feel a little better...you know these darn car and trucks are like my kids sometimes and I worrie to much!
wink.gif
 
Most shops will quote you somewhere between $300 and $500. Mine cost me $300 but I brought some of my own fluids and did some of the work. It's not to hard if you have a some mech skills. The most technical part was probably getting the dist back in right. I would do it my self if I was to do it again. I was scared of the EFI and such cause all I have worked on is old stuff. Plan on doing and oil change right after to get all the crap out. Do plan on having it done though -it's not if it's when. Just a fact of life on these engines. I ditched the dexcool too because I kept having baby cr%p looking stuff show up in the rad. Where abouts in CO are you? I know a couple of good shops.
Also you can tell if you have an oil cooler by looking at the drivers side of the rad. If it has a cooler there will be two line coming into the rad from the oilfilter adapter. Looks almost exactly like the right side where the trans cooler goes into the rad.
 
I'm in Windsor. I have been Using Windsor Auto Repair sence I found out about them. So far they have done me right and all work has been good. who do you reccomend?
 
I would also bet its your intake manifold gasket. I have a 98 silverado with the 5.7L and its had to have intake gaskets done twice since It was new. Once at 24,000 miles and again at around 59,000 miles. The first time it leaked externally and the second time internally.

Oil analysis detected the leak the second time around because increased levels of potassium.

I got lucky on the repair price and was only charged $193 from a local shop. My truck was the third one in a week he had done. Its a known problem with this engine and they all have to have it done eventually. I had quotes all the way up to $800.

Wayne
 
quote:
Originally posted by Quest:
No offense Chris but we are talking about ppm here (parts per million). 25 ppm of Potassium can be attributed to oil additives if memory serves.

As another satisfied ARx user don't we all want to make our engine last longer?

q.
Click to expand...
Q, you're right about Potassium also being an additive component, but what alarms me about this one is that we are seening Potassium and Sodium elevated together. That's a virtual calling card for a coolant leak. Either one alone might warrant a more cautious approach, but with this, I'd at least investigate further NOW.
 
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