Burning oil. Low miles
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On The Tree
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Burning oil. Low miles Hey guys. Quick background to get it out of the way. LM7 5.3 in a 2wd truck Low miles, like 110k. I have been noticing a little tail pipe smoke, mostly at idle cause thats the only time i am out of the truck to see it. I changed my oil the other day and I MUST have been low like a couple quarts due to the small amount that drained. But no engine noise, no ticking, motor seems healthy as always so I was kind of dismissing the smoke until the oil change. It is not leaking and it is not contaminating the coolant…My first thought was rings. But now I am wondering maybe valve seals, or even guides? Just need a little help diagnosing, what to look for. Obviously I will be keeping an eye on the oil level going forward. And i am not typically hard on the truck by any means so I an a little stumped. What preliminary things can i start looking for that doesn’t involve a massive tear down. I do have a leak down but are there even more simple tests?
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On The Tree
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The oil looked normal. No milky tint. I always change my own oil. I did not see anything unusual other than what seemed to be only a small amount drained out. I guess i gotta just start straight with the leak down and see what I can find.
How many miles on the oil? I ask because the LS engines use oil. The GM PCV setup pulls a lot of vacuum and it sucks oil mist into the intake. I change my oil in my daily ‘12 silveraydo and our work van fleet every 3-3500 miles. They are all….even my brand new vans….always almost a quart low at 3-3500 miles. If you stretch your oil changes out to 5k or more, your prolly low on oil. The PCV in these engines draws a lot of oil into the intake, in the name of emissions. It’s BS. Makes a mess in the intake. Turns into a jelly like substance in the intake. Just a thought…
Thread Starter
On The Tree
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How many miles on the oil? I ask because the LS engines use oil. The GM PCV setup pulls a lot of vacuum and it sucks oil mist into the intake. I change my oil in my daily ‘12 silveraydo and our work van fleet every 3-3500 miles. They are all….even my brand new vans….always almost a quart low at 3-3500 miles. If you stretch your oil changes out to 5k or more, your prolly low on oil. The PCV in these engines draws a lot of oil into the intake, in the name of emissions. It’s BS. Makes a mess in the intake. Turns into a jelly like substance in the intake. Just a thought…
Last edited by chalou88; Sep 17, 2023 at 11:01 PM. Reason: Additional info
My 2000 LS1 used enough oil (no smoke, thanks to cats) that the first few times I took it to the strip, it used more than I thought. I noticed each time I ran it, the runs got slightly faster than the preceding runs the week before. In a C5, a low oil light comes on eventually (if it's working correctly!). Mine came on just after my last run of the day, which was also the fastest trap speed I'd ever had at that point. I knew it came on when there was still about 4 qts of oil left in the sump. Glad I brought a couple qts with me! So I dumped a qt in it to get home, then changed it. So, some early LS1s also use oil. My car had under 30,000 miles when this happened. Like quite a few early LS1s, it also had the common LS1 piston slap when under 55° ambient temps prevailed....
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Thread Starter
On The Tree
Joined: Feb 2018
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My 2000 LS1 used enough oil (no smoke, thanks to cats) that the first few times I took it to the strip, it used more than I thought. I noticed each time I ran it, the runs got slightly faster than the preceding runs the week before. In a C5, a low oil light comes on eventually (if it's working correctly!). Mine came on just after my last run of the day, which was also the fastest trap speed I'd ever had at that point. I knew it came on when there was still about 4 qts of oil left in the sump. Glad I brought a couple qts with me! So I dumped a qt in it to get home, then changed it. So, some early LS1s also use oil. My car had under 30,000 miles when this happened. Like quite a few early LS1s, it also had the common LS1 piston slap when under 55° ambient temps prevailed....
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From: Bostwick, GA.
?? 
JK!
I've had a couple of the earlier 5.3's smoke very little but use oil as Scott mentioned.
Both were higher miles. New valve seals did reduce it considerably.
I failed to mention my go-to first step procedure for diagnosing this issue, in my above post, and that is pull the spark plugs. Plug…or plugs…should show oil if it’s burning it. Maybe post up pics of plugs for us.
Thread Starter
On The Tree
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Question. Shouldn’t I expect to see some oil on one of the cylinders? Correct me if I’m wrong. I thought it was #8 hole?
Open the blade on the throttle body and perform a leak down. If you hear hissing coming through the exhaust and/or the intake manifold on a cylinder where the valves are opened it will be due to worn valve guides.
Last edited by 01CamaroSSTx; Sep 19, 2023 at 06:03 AM.
Hey guys. Quick background to get it out of the way. LM7 5.3 in a 2wd truck Low miles, like 110k. I have been noticing a little tail pipe smoke, mostly at idle cause thats the only time i am out of the truck to see it. I changed my oil the other day and I MUST have been low like a couple quarts due to the small amount that drained. But no engine noise, no ticking, motor seems healthy as always so I was kind of dismissing the smoke until the oil change. It is not leaking and it is not contaminating the coolant…My first thought was rings. But now I am wondering maybe valve seals, or even guides? Just need a little help diagnosing, what to look for. Obviously I will be keeping an eye on the oil level going forward. And i am not typically hard on the truck by any means so I an a little stumped. What preliminary things can i start looking for that doesn’t involve a massive tear down. I do have a leak down but are there even more simple tests?
Thread Starter
On The Tree
Joined: Feb 2018
Posts: 163
Likes: 2
I did not think that bad valve guides or valve seals would be visibly bad. Unless they are destroyed in which case i would have noticeable noise / heavy smoking ??
