Oil burning question on GM Vortec 350
- Thread starter Chris B.
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We use M1 0W-40 in my buddy's '97 Suburban C2500 with the 7400. We use Liqui-Moly Pro-Line Engine Flush at every oil change, and so far it's just less than half a quart low when it hits 8,000 km (5,000 miles) on the oil. The engine barely sees anything over 2,500 rpm, if that has anything to do with it and my buddy literally drives it like an old granny.
I had a 97 gmc sierra with the 5.7 had 185k when i traded it and never got below the add mark in 3k miles on gtx 10w30. Also had a 99 chevy k1500 with 5.7 it had 170k when i traded it and it used 1-2 quarts at 3-4k with vwb, max life or motorcraft 5w30. I tried different brands to reduce consumption but stuck with 5w30 only and it used approximately the same amount regardless of brand.
It is a very reliable engine even if it uses a bit of oil change it every 3k and drive lots of miles with it at ease, mine has 140k and counting on it, Ill post up some pics later.
Ive seen alot of small block chev's and owned quite a few and all of them used under a quart in 5000km. I think your consumption is excessive. If you want to play with types and flushes and weights that is your choice for sure. But on a truck that is that nice it is worth dropping a new crate motor in. I did it on a 1990 with the tbi 350. I got the dealer to put in a lt1 350 block with all my old fuel injection and other acessories put back on. that engine is still going strong today owned by my father and with over 500,000km on the truck and about 250,000 on the engine. It still doesnt use much oil less than 1 litre per oci. My engine swap cost under 3000$ for the dealer to do it. So in my eyes well worth it.
These trucks are known for sucking oil through the pcv. This nre valve is a fixed type and should clear up your problem,
GM P/N 12572717
GM P/N 12572717
The Professor recommends to run Quaker State High Mileage 5W-30, with a quart of MMO mixed in. The Professor also says, to top it of with oil, and for the next few OCI's, sub in a quart of MMO. Then, use the QSHM 5W-30 for regular OCI's.
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Originally Posted By: abycat
Ive seen alot of small block chev's and owned quite a few and all of them used under a quart in 5000km. I think your consumption is excessive. If you want to play with types and flushes and weights that is your choice for sure. But on a truck that is that nice it is worth dropping a new crate motor in. I did it on a 1990 with the tbi 350. I got the dealer to put in a lt1 350 block with all my old fuel injection and other acessories put back on. that engine is still going strong today owned by my father and with over 500,000km on the truck and about 250,000 on the engine. It still doesnt use much oil less than 1 litre per oci. My engine swap cost under 3000$ for the dealer to do it. So in my eyes well worth it.
My 87 305 1qt at 3k. 89 350 1-1.5qt at 3k. 97 350 no consumption at 3k. 99 350 1-2qt at 3-4k. So my experiences have been quite varied. Everyone has different opinions but i certainly would not be looking to put an engine in for 15oz at 2500 miles. More than likely replacing the valve seals would significantly reduce the consumption. Just check for blue smoke on startup that is a sign of a valve stem seal issue. Although in my opinion the OP has an acceptable amount.
Ive seen alot of small block chev's and owned quite a few and all of them used under a quart in 5000km. I think your consumption is excessive. If you want to play with types and flushes and weights that is your choice for sure. But on a truck that is that nice it is worth dropping a new crate motor in. I did it on a 1990 with the tbi 350. I got the dealer to put in a lt1 350 block with all my old fuel injection and other acessories put back on. that engine is still going strong today owned by my father and with over 500,000km on the truck and about 250,000 on the engine. It still doesnt use much oil less than 1 litre per oci. My engine swap cost under 3000$ for the dealer to do it. So in my eyes well worth it.
My 87 305 1qt at 3k. 89 350 1-1.5qt at 3k. 97 350 no consumption at 3k. 99 350 1-2qt at 3-4k. So my experiences have been quite varied. Everyone has different opinions but i certainly would not be looking to put an engine in for 15oz at 2500 miles. More than likely replacing the valve seals would significantly reduce the consumption. Just check for blue smoke on startup that is a sign of a valve stem seal issue. Although in my opinion the OP has an acceptable amount.
Originally Posted By: Chris B.
How do you tell if the PCV is good or bad?
When in doubt, simply replace. I've had PCVs pass the shake and suck tests, but still cause condensation in the oil. A subsequent PCV replacement eliminated the problem.
How do you tell if the PCV is good or bad?
When in doubt, simply replace. I've had PCVs pass the shake and suck tests, but still cause condensation in the oil. A subsequent PCV replacement eliminated the problem.
Originally Posted By: Garak
Originally Posted By: Chris B.
How do you tell if the PCV is good or bad?
When in doubt, simply replace. I've had PCVs pass the shake and suck tests, but still cause condensation in the oil. A subsequent PCV replacement eliminated the problem.
Does the PCV just pop off and pop a new one on?
Originally Posted By: Chris B.
How do you tell if the PCV is good or bad?
When in doubt, simply replace. I've had PCVs pass the shake and suck tests, but still cause condensation in the oil. A subsequent PCV replacement eliminated the problem.
Does the PCV just pop off and pop a new one on?
It just pops right off, takes about 30 seconds.
Originally Posted By: Chris B.
How do you tell if the PCV is causing condensation to get in the oil.
You don't. As I mentioned, you could do the shake and suck tests, but it might pass these rudimentary tests but still be causing the problem. Just replace it with the OEM part number indicated in this thread. I don't even bother with aftermarket PCV valves.
How do you tell if the PCV is causing condensation to get in the oil.
You don't. As I mentioned, you could do the shake and suck tests, but it might pass these rudimentary tests but still be causing the problem. Just replace it with the OEM part number indicated in this thread. I don't even bother with aftermarket PCV valves.
Originally Posted By: Garak
Originally Posted By: Chris B.
How do you tell if the PCV is good or bad?
When in doubt, simply replace. I've had PCVs pass the shake and suck tests, but still cause condensation in the oil. A subsequent PCV replacement eliminated the problem.
I had similar issues described. Mostly it was the oil use for no apparent reasons. The vortec engines don't have the same valve stem seals as their earlier counterparts. Late model is definitely better and there was a TSB for this issue and this was the part number for it.
Originally Posted By: Chris B.
How do you tell if the PCV is good or bad?
When in doubt, simply replace. I've had PCVs pass the shake and suck tests, but still cause condensation in the oil. A subsequent PCV replacement eliminated the problem.
I had similar issues described. Mostly it was the oil use for no apparent reasons. The vortec engines don't have the same valve stem seals as their earlier counterparts. Late model is definitely better and there was a TSB for this issue and this was the part number for it.
I think some of the vortecs had seal issues as compared to all of the tbi motors. My 99 chevy puffed the blue smoke on startup as does my friends 98 chevy which he still owns. My 97 gmc and uncles 96 gmc did not. I always changed my pcv valve when i changed the fuel filter on those trucks. My uncle fixed a consumption problem on his by replacing the pcv and i just figured better safe than sorry.
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ya the PCV is very cheap and easy to replace no sense in not doing that to see if it helps
I've changed my PCV valve a few times over the years, always using an AC-Delco one. I have never noticed any blue smoke on startup with this truck.
PCV valve change on this engine is very easy. Just disconnect the vacuum hose from the valve and then pull valve out of the valve cover.
On my truck, I have also changed the valve cover rubber grommet that the PCV valve goes into because over time, the PCV valve gets loose in the grommet and then you don't have a good seal.
Wayne
PCV valve change on this engine is very easy. Just disconnect the vacuum hose from the valve and then pull valve out of the valve cover.
On my truck, I have also changed the valve cover rubber grommet that the PCV valve goes into because over time, the PCV valve gets loose in the grommet and then you don't have a good seal.
Wayne
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