Truck low oil

[gride]

Yukon 5.3l. I reset the oil monitor when I changed the oil. It's at 43%. I got one low oil check message yesterday. Checked oil and it's definitely low. Can I add some more oil? I would have already but I don't remember what brand I used last time. I know 5/30 synthetic, but should I change the oil or can I just add some synthetic

[swc5150]

What year is the Tahoe? Hopefully you're not subject to the 5.3 w/ displacement on demand curse. (I suffered it with my Saab 9-7) Oil builds up in the cylinders that are not in "use" when DOD is activated, and finds its way past the rings to the combustion chamber. With that said, I would just add oil until your due for an entire change out, and keep watch on the level. After 65k miles, mine got progressively worse. There is an aftermarket way to disable DOD, but naturally, your dealership won't do it.

Of course, there are more reasons an engine would burn oil, this is just what I dealt with.

[crobi2]

Hey, you gotta watch out on some of the 5.3 engines in Yukons esp. around 2003-2005ish. They had a series of bad head castings that develop thin cracks in the water passages right about the head bolts and lose coolant into the crankcase. It's very strange, but sometimes the issue shows up with decreased oil (I don't understand the mechanism). But as it gets worse, you will notice a loss of coolant and it can eventually get bad enough to increase the crankcase volume.

I hope you don't have this problem.

Regardless of what's going on, you do need to figure out where your oil is going. That low oil sensor sits pretty low so you gotta be real low for it to go off.

[NCH2oSki]

I was told by my dealer that using 1 to 2 quarts of oil with the 5.3's is pretty common. My truck (08' sierra) sees 30K per year of highway miles, and probably 10K per year of city/country, or towing and it is using 1 quart at 5K miles. I run about 6K miles per oil change. I just hit 99,955 miles last night, and it feels as strong as the first day I purchased it. I hope this isnt an issue later down the road, as I planned on keeping this one for another 100K or more.

[gride]

well it's an 04. and my coolant was low last week so i added some and it was fine for a few days, then went low again. cant find any leaks. i guess i'll take it to the shop after the weekend. if i do have these previously mentioned problems do i need a new engine?

[jimmyj]

...japanese......

[crobi2]

I'm sorry to hear about the symptoms you are having, it sounds like that problem. Here is the TSB.

GM TSB# 06-06-01-019B (came out 06-12-2007)
Subject: Information on Gradual Coolant Loss Over Time With NO EVIDENCE OF LEAK FOUND

The TSB shows pictures of where the heads fail and the leaks form. Unfortunately, you have to pull off the valve cover to see the casting mark and the telltales from the leak(s).

Really unfortunate for most people is that their mechanic first sells them a new water pump (and/or other stuff) before the actual diagnosis is made because even the dealer mechanics (seem) to not know about this.

Coolant does not just "disappear" from an engine. You can go for years without having to add coolant.

If you have been running the GM orange coolant, I don't believe that it necessarily destroys your bearings like the silicates in the old green stuff can. This may be why GM switched to this coolant.

Also, I think you mentioned running synthetic oil in your engine. Some of the high quality synthetics seem to be able to emulsify with the water better which may protect the bearings (but it makes it hard to tell that you have water in your oil by looking at the stick). But if you take off your oil filter and it comes out in clumps, you will know (but it only does that when the leak is REALLY bad and the oil pressure starts going up).

With that all said, I went through this two years ago and gambled by buying new head castings and using all of the old valves/springs/etc. Haven't touched the coolant level in two years and the engine uses very little oil and runs like a dream. -So it seems to have paid off. I only had about 86K miles on the block at the time. I am about 130K now.

You have to first figure out if this is what is wrong with your engine and then decide if it is worth putting new heads on or just getting a long block.

No one at GM seems to know which engines got the castech heads and which didn't but there are probably a lot of ticking time bombs driving around out there.

[gride]

Thanks for the info. I'll relay it to my mechanic and let y'all know what's up.

[gride]

took it to gmc dealer. they said it's definitely the water pump. want 675 to replace it w/ lifetime warranty. sounds like a huge rip off considering the pump is less than 100$. i told them about the head castings and they said no, its the pump. what do ya'll think. i've used a bottle of coolant in two weeks. as for the oil, they said i'ts getting older and to change it at 50%. he does that on his 02 yukon. tell me ya'lls opinions.

[gride]

Take 98$ off that for ac reprogramming and the gm pump with lifetime part and labor warranty is 254+tax and a new inlet with new thermostat is 60$. About 2 hours labor at 93$ an hour. What do y'all say the average time to do the work should be?

[crobi2]

well it's an 04. and my coolant was low last week so i added some and it was fine for a few days, then went low again. cant find any leaks. i guess i'll take it to the shop after the weekend. if i do have these previously mentioned problems do i need a new engine?

Did they find a leak and show you? I sure hope everything works out for you.