Compression test results!

[bzubke1]

So i've had some excessive oil consumption lately. About a quart everythousand miles. I decided to do a compression test today and here were the results. BTW I have 101K miles.
Cylinder 1= 160-162
Cylinder 2= 155-157
Cylinder 3= 157-158
Cylinder 4= 142-145 without oil 150-151 with oil.
Cylinder 5= 150-152
Cylinder 6= 160-162
Cylinder 7= 150
Cylinder 8= 150
So, everything looked good to me except cylinder #4. The ring must be worn. I had planned on a heads cam swap in the next few months or so but now i'm wondering if I should get a new shortblock instead. I'm not going to get anything crazy prolly a lightly used mustang or explorer shortblock. What would yall do in my situation? Keep the stock shortblock and do the heads cam or get a new one.
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[98-5.0]

honstly those numbers look good to me as well. even cylinder 4 looks ok. i dont think that would cause a huge amount of oil consumption...and also...half a quart of oil between a routine 3000 oil change is almost kinda normal for a motor with 100k on the clock believe it or not. the new chevrolet law now is up to a quart of oil evey 5000 miles is ok to a gm vehicle even under warranty...thats why the suck imho. but i wouldnt worrie to much about that....but in your case...1 quart every 1k . thats kinda alot. i would deffinatly look at your valve seals and even if you cant make that decision they are like 12 bucks and you could probably do them yourself with the heads on the car and a air compressor since you know what your doin with a compression test...see about that and also just check for leaks obviously...rear main seal is a big one...you probably know that much...but let me know whats up with the valve seals...and ill try to think up some other possible issues...

 

[cdsmith_2002]

The Haynes manual says 100psi minimum and all cylinders should be within 15psi of the highest reading. I would not me Bzubke1's suggestion about the valve steam seals. Are you using 10W30?

 

[lilredstang97]

ive read that when a motor starts to get more wear and tear on it and it starts to consume more oil you can put a heavyer oil in the motor and it will help it out on the oil consumption. dont hold me true to this though i havent tried it my self.

 

[dave1989]

if its not using oil its cause its parked lol shoot you a lil lucas in there

 

[modo]

compression test is pretty pointless... all it is telling you is that there are no holes in the piston. if you want to know the real status of the rings do a leak down test.

 

[bzubke1]

Man this thread is old. I actually did a leadown test recently and everything looked good. My oil consumption was coming from worn out valve guides.