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Synthetic Oil

ArmyAviator

By ArmyAviator
in Ask A GM Technician

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ArmyAviator Enthusiast

ArmyAviator

Posted
Posted

2000 GMC Sierra 5.3 4x4 with 190K; solid truck; no oil burn; no leaks; tediously maintained. About 50K ago, tech talks me into full synthetic Mobil 1. I have synthetic in 1-ton diesel and 07 Tahoe, so I go for it.

 

All is well....I think....but of late, at 5-7K, I change oil and it's "muddy". Like dark milk chocolate, and there are a few "lumps" at the bottom of stream....sorta gelatin-like. it's not true milky like water in it, though there is a small amount of condensation under oil cap; tech says that's normal. ?? Could the Mobil 1 be cleaning up a lotta crap in there? Truck is rarely off road.

 

Oil pressure is 38-40 @ idle, maybe 42-44 @ cruise. I do notice that just last week, at start, the oil pressure comes up then drops really low for a blink and comes right back up with no further repeat.

 

No overheating; coolant is okay but it's always "used" about a pint every 3K.

 

Thoughts?

 

Thank you.

--Bryant

Zembonez Senior Enthusiast

Zembonez

Posted
Posted
Those are all symptoms of coolant leaking into the oil.

+1

 

Synthetic oil never comes out muddy unless it is contaminated. Mine comes out looking better like new dino oil after 5K. Couple that with the fact that no truck "uses" coolant normally. You have a small leak internally somewhere. Can't be doing your main and rod bearings any good.

  • 4 weeks later...
Got V8? Enthusiast

Got V8?

Posted
Posted
2000 GMC Sierra 5.3 4x4 with 190K; solid truck; no oil burn; no leaks; tediously maintained. About 50K ago, tech talks me into full synthetic Mobil 1. I have synthetic in 1-ton diesel and 07 Tahoe, so I go for it.

 

All is well....I think....but of late, at 5-7K, I change oil and it's "muddy". Like dark milk chocolate, and there are a few "lumps" at the bottom of stream....sorta gelatin-like. it's not true milky like water in it, though there is a small amount of condensation under oil cap; tech says that's normal. ?? Could the Mobil 1 be cleaning up a lotta crap in there? Truck is rarely off road.

 

Oil pressure is 38-40 @ idle, maybe 42-44 @ cruise. I do notice that just last week, at start, the oil pressure comes up then drops really low for a blink and comes right back up with no further repeat.

 

No overheating; coolant is okay but it's always "used" about a pint every 3K.

 

Thoughts?

 

Thank you.

--Bryant

Got V8? Enthusiast

Got V8?

Posted
Posted
2000 GMC Sierra 5.3 4x4 with 190K; solid truck; no oil burn; no leaks; tediously maintained. About 50K ago, tech talks me into full synthetic Mobil 1. I have synthetic in 1-ton diesel and 07 Tahoe, so I go for it.

 

All is well....I think....but of late, at 5-7K, I change oil and it's "muddy". Like dark milk chocolate, and there are a few "lumps" at the bottom of stream....sorta gelatin-like. it's not true milky like water in it, though there is a small amount of condensation under oil cap; tech says that's normal. ?? Could the Mobil 1 be cleaning up a lotta crap in there? Truck is rarely off road.

 

Oil pressure is 38-40 @ idle, maybe 42-44 @ cruise. I do notice that just last week, at start, the oil pressure comes up then drops really low for a blink and comes right back up with no further repeat.

 

No overheating; coolant is okay but it's always "used" about a pint every 3K.

 

Thoughts?

 

Thank you.

--Bryant

 

 

I have a 2001 5.3 Silverado. I had a oil analysis done by blackstone labs and ran Q synthetic for around 6k, which normally I wouldnt do, but I was reading all this stuff that synthetic could run longer than conventional. Blackstone said that I had abnormally high amounts of lead, of course from bearings. i also had Iron, and another type of metal present, I think that he said aluminum from the pistons. I do have piston slap. The tech that I had spoken to told me that for some reason these trucks bearings seem to have problems when switching to synthetic, he told me that he would use regular castrol and change it every 3k. I also had sodium which he said that Q uses in their oil and that they would do a free analysis to see if it is the oil, he said that if that is not the case then it would be from antifreeze, which it doesent seem that I am losing antifreeze.

If your antifreeze is going down at all I would find the cause of this right away. The tech told me that it is probably an intake gasket which I have read that these trucks have a problem with. You probably should maybe see about getting a pressure test done. I know that I will be watching mine close now so I dont dilute my oil.

markw8 Enthusiast

markw8

Posted
Posted
2000 GMC Sierra 5.3 4x4 with 190K; solid truck; no oil burn; no leaks; tediously maintained. About 50K ago, tech talks me into full synthetic Mobil 1. I have synthetic in 1-ton diesel and 07 Tahoe, so I go for it.

 

All is well....I think....but of late, at 5-7K, I change oil and it's "muddy". Like dark milk chocolate, and there are a few "lumps" at the bottom of stream....sorta gelatin-like. it's not true milky like water in it, though there is a small amount of condensation under oil cap; tech says that's normal. ?? Could the Mobil 1 be cleaning up a lotta crap in there? Truck is rarely off road.

 

Oil pressure is 38-40 @ idle, maybe 42-44 @ cruise. I do notice that just last week, at start, the oil pressure comes up then drops really low for a blink and comes right back up with no further repeat.

 

No overheating; coolant is okay but it's always "used" about a pint every 3K.

 

Thoughts?

 

Thank you.

--Bryant

 

 

I have a 2001 5.3 Silverado. I had a oil analysis done by blackstone labs and ran Q synthetic for around 6k, which normally I wouldnt do, but I was reading all this stuff that synthetic could run longer than conventional. Blackstone said that I had abnormally high amounts of lead, of course from bearings. i also had Iron, and another type of metal present, I think that he said aluminum from the pistons. I do have piston slap. The tech that I had spoken to told me that for some reason these trucks bearings seem to have problems when switching to synthetic, he told me that he would use regular castrol and change it every 3k. I also had sodium which he said that Q uses in their oil and that they would do a free analysis to see if it is the oil, he said that if that is not the case then it would be from antifreeze, which it doesent seem that I am losing antifreeze.

If your antifreeze is going down at all I would find the cause of this right away. The tech told me that it is probably an intake gasket which I have read that these trucks have a problem with. You probably should maybe see about getting a pressure test done. I know that I will be watching mine close now so I dont dilute my oil.

 

markw8 Enthusiast

markw8

Posted
Posted

I would never believe that the bearings would be hurt by switching to synthetics. The tech blameing the oil, is either mistaken, or just doesn't like synthetic oil. Mark.

Zembonez Senior Enthusiast

Zembonez

Posted
Posted
I would never believe that the bearings would be hurt by switching to synthetics. The tech blameing the oil, is either mistaken, or just doesn't like synthetic oil. Mark.

I agree 10000000000%

 

Synthetic oil will not harm anything. It's quite the opposite actually. The only way the lubricant caused that is if it was contaminated by something.

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