[Maverick]

My brother was checking the oil in his 96 Z71 and there was no oil in it He dosnt really remember the last time he changed it but he used a full synthetic. It didnt leak out it dosnt smoke. It was doing its job you couldnt tell it was that low 4.5 qrt low. It takes 6. I got to thinking about it 4000 miles ago I use full synthetic in my 2000 GMC Z71 so I checked it and it was 2 qrts low. So whats the deal were dose it go?? Dose it slip by the pistons during high rpms and blow out the exhust? Any Ideas??

[1meancuda]

Did you both switch after using regular for a time? How many miles are on the trucks?

[4 Jaw Chuck]

All engines use oil, if your engine is not using oil then it is being replaced with fuel and blowby residue and water. It is entirely normal for an engine to burn oil, don't worry about it and just check it more regularly.

I actually found my engines burn less oil with synthetic. How long was it since you last checked your oil? 1/4 litre per 600 miles is normal and some manufacturers even say 1/2 litre per 600 miles is normal. When an engine stops using oil that is a sign of wear.

[Maverick]

My truck the 2000 has 40,000 miles I just got it when it had 35,000. this was my first oil change since I have had it. I change it again this weekend and used the Quaker State 4X4 blend. Brothers truck has like 150,000 miles. Just never have had one use that much oil with regular oil. Kinda wierd. Its probably good brother had it in his there is no telling how long he has been driving with it that low.

[willys36@aol.com]

Synthetics got a reputation early in their history of causing external leaks by softenting gaskets. I have never heard of them causing more consumption though.

Come on Maverick, ten slaps with a wet noodle for not remembering when you last changed your oil. Repeat after me, "every 3,000 miles, every 3,000 miles, every 3,000 miles . . . "

[Maverick]

NO NO NO! I remember when I change mine. Its my brother that dosnt remember. Iam suprised he even checked it when he did.

[1meancuda]

I've heard that it is fairly common for an engine to start consuming synthetic oil when they have not consumed regular oil in the past. I would suggest that you simply keep an eye on the fluid, as some people have told me that the consumption goes down or away after a period of time.
To truly find out what is going on, why not just pull some spark plugs and check for fouling? I have also heard that problems with your PCV could be causing the consumption also. Not to say that this is what is happening to you, they are mearly suggestions for things to try.
Good luck and keep me posted on what you find!