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Drinking OIL / Bad gas mileage


93buicklesabrelmtd
07-12-2005, 10:27 PM
95 Burb been drinking alot of oil lately. No traces of leaks no where.
Oil changes every 3500 miles but hardly any oil in there when time to change.

Also it has been using alot of gas lately too.

Engine 5.7L Miles 140,000

Anyone had this problem before?

Is this normail oil consumption for these engines? gmc 1500?

trappie
07-13-2005, 08:42 AM
Might want to check PCV valve, I have heard that when they go bad they can cause both of those problems.

94century
07-13-2005, 11:01 PM
General Motors puts normal oil consumption as one quart every 3,000 miles. I would check inside your air cleaner for oil. Also, check to see if any is getting into the radiator. Are the RPM's running high? If so make sure it is going into 4 gear. I have an 88 Sububan with a 454 and a 3 speed automatic, and when I do a lot of interstate driving it does the same thing. At higher RPM's any engine would use more oil.

93buicklesabrelmtd
07-15-2005, 11:55 PM
Might want to check PCV valve, I have heard that when they go bad they can cause both of those problems.

How do I check the PCV valve on this thing??

94century
07-16-2005, 12:22 AM
Pull it out and shake it, if you hear it rattle then it is OK; if not replace it. I would replace it anyway.

93buicklesabrelmtd
07-17-2005, 03:50 PM
Pull it out and shake it, if you hear it rattle then it is OK; if not replace it. I would replace it anyway.

Pulled out and it rattled. Re inserted it.
Any more ideas why this think has a real thirst for oil and gas lately?
Would the o2 have anything to do with this?

94century
07-17-2005, 04:53 PM
Well, does it smoke on start up? It could be valve seals, or piston rings. If it smokes on start up and clears after a few minutes, then it could be valve seals. Do a compression check to see if you have any weak cylinders.

93buicklesabrelmtd
07-19-2005, 10:28 AM
Well, does it smoke on start up? It could be valve seals, or piston rings. If it smokes on start up and clears after a few minutes, then it could be valve seals. Do a compression check to see if you have any weak cylinders.

No smoke at all on startup!
Yesterday the check engine light came on, while in traffic with the AC running. I believe she stalled also. Started right back up. Turned off AC and the check engine light went off. Now I cant get the light to come back on.

She is really really drinking gas these days.
Truck drives mostly on the highways.

Is this truck OBD 1 or 2?
Gmc Suburban 1500 with the 5.7L
1995

94century
07-19-2005, 07:54 PM
95 is OBD-1. It is not hard to check the codes. Get a Haynes manual from a parts store and it will tell you how to check it and give you a list of codes. Also have you changed to any peticular brand of gas? Had a 77 chevy truck with a 350 that would use gas big time until I put BP 93 octane in it and that solved the problem. Why it did this I will never know. I run 93 octane in my Century and get about 3 mpg better than the lower grades, so it is worth it.

93buicklesabrelmtd
07-20-2005, 07:49 AM
I use 87. The truck has some advance timing addon which, in its manual wants you to use premium gas. This is how we bought the truck. It was used for towing. 87 octane is what we've been pumping, working fine for over a 1 year. Mileage started going down about 1mnth ago. I am going to pickup a Haynes manual today or tommorw.

Could a bad fuel filter or something of that nature cause this problem?

Thanks for all your help!!

93buicklesabrelmtd
07-20-2005, 07:50 AM
I use 87. The truck has some advance timing addon which, in its manual wants you to use premium gas. This is how we bought the truck. It was used for towing. 87 octane is what we've been pumping, working fine for over a 1 year. Mileage started going down about 1mnth ago. I am going to pickup a Haynes manual today or tommrow.

Could a bad fuel filter or something of that nature cause this problem?

Thanks for all your help!!

trappie
07-20-2005, 11:25 AM
Why not change out the PCV valve? Whether is "shakes" or not it only costs a couple bucks and takes seconds to change. A bad O2 sensor could possible cause the fuel consumption problem, but not sure about oil consumption.

93buicklesabrelmtd
07-20-2005, 12:03 PM
Why not change out the PCV valve? Whether is "shakes" or not it only costs a couple bucks and takes seconds to change. A bad O2 sensor could possible cause the fuel consumption problem, but not sure about oil consumption.

I guess the oil consumption is probrably normal.
Checked today and still full. How many quarts does this thing really take?
Truck drives alot of miles highway and city everyday.
I will replace the PCV valve this week.
O2 is what im thinking right now.
Service Engine Soon light came on today again. (2nd day it happened)
Then it went off in 5 minutes! Engine temp was around 200

Where are the O2(s) located on this thing?
May just order them online and wait..

Also does anyone has the codes for ODB1 for a 95 GMC Suburban 1500 5.7L

I want to do the test, but I dont have a book yet.
Thanks for help people.

94century
07-20-2005, 04:48 PM
Should hold about 5 quarts including oil filter. The O2 sensor is located in the exhaust pipe close to the engine.

93buicklesabrelmtd
07-21-2005, 10:47 AM
Should hold about 5 quarts including oil filter. The O2 sensor is located in the exhaust pipe close to the engine.

I believe I toped off with 6qtrs this time.

I do have a question about the gas guage..

Does this thing have a gas light when its really low on fuel?
I never seen one come on. I normally fill her up when its about the 2nd orange line. But yesterday had no money, and was wondering if the gas light would come on. If im really empty?
Or would the Check Guages light come on?

It did take me home safely. So how much gas is really in this thing? travelled like 50 miles back home.

The Suburban manual says the guage will first ready empty before you are out of fuel.

suburban_lee
07-21-2005, 01:57 PM
I believe I toped off with 6qtrs this time.

I do have a question about the gas guage..

Does this thing have a gas light when its really low on fuel?
I never seen one come on. I normally fill her up when its about the 2nd orange line. But yesterday had no money, and was wondering if the gas light would come on. If im really empty?
Or would the Check Guages light come on?

It did take me home safely. So how much gas is really in this thing? travelled like 50 miles back home.

The Suburban manual says the guage will first ready empty before you are out of fuel.

I've driven mine down to about 3 gallons, and I don't think there's a light. Never one that I've seen, at least.

The tank holds 42 gallons total, and when the guage hits the first line on its decent to empty, you probably have about 5 to 7 gallons in the tank.

Brianboe
12-23-2005, 06:49 PM
I am new to this forum and this is my first post. I am hoping to get some answers somewhere about my vehicle. I'm definitely not getting any help at my chevy dealer service center.

Heres my problem. I bought a 2002 express van brand new and noticed after about 12 to 15k that it got about 9 mpg and 1500 mpq(miles per quart) on the oil. My motor is the 5.7 liter 350. Before I owned the 2002 I had a 1998 with the 5.7 350. It didn't burn a drop of oil and it got around 18-20mpg and it had some guts if you know what I mean.

I have been on several oil consumption tests and have had the runaround about how GM allows up to 1 qt/1000miles and the gas mileage is normal. Can anyone help me out here or am I pretty much another GM victim?

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