Where did the oil go.

[bluewater19]

I have a 1999 Gmc suburban with a 5.7L vortec v-8.<br />Since I have owned it since 40k miles I have changed the oil every 5,000 using synthetic 5w30 and I have always consumed 1 quart per oil change. Last oil change I checked at 3000 miles before driving it on a 300 mile trip and was 2.5 quarts low. I refilled it and checked it out durring the trip and it used a quater of a quart I park it in the driveway and it has no leaks. Heres the weird thing, I changed the oil and filter when I got back and have been checking it every time I get gas I have 4000 miles on this oil change and have only used a little less than 1 quart. Was it a stuck oil ring? I always check for leaks after every oil change and put the other half of quart of oil in the spot where the 2nd battery would go on a diesel so I can keep it topped off. How could it burned 2.5 quarts so fast and then stop burning it? I am stumped.

 

[LubeDude]

Re: Where did the oil go.

HMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM!<br /><br />Well, we all know it doesnt just dissapear, or evaporate into thin air.<br /><br />Providing it was filled all the way in the first place, Which Im sure it was as you seem to keep a good Eye on things, It may be a very dirty air filter causing the engine to have to work harder to get air thus drawing oil around the rings, (Not likely), Maybe a faulty PVC Valve,????????<br />Im just fishing, Strange. things happen sometimes.<br /><br />Why a 5W-30 there in California? I think that I would go to a 10W-30 at least, and maybe a 10W-40. Not that this is the problem, but you would use less if you changed.

 

[KennyKenCan]

Re: Where did the oil go.

bluewater19,<br /><br />Those trucks are infamous for Oil Cooler lines seeping (leaking).<br /><br />This seeping usually doesn't leave spots on your driveway or garage floor, so detection is difficult.<br /><br />If you look under the truck, I'm sure you will find oil where it don't belong.<br /><br />So far, I have found no cure for this problem, other than replacing the hoses, but that is only temporary, as it will leak again.<br /><br />Also, and I know this may sound dumb, but are you sure you tightened the oil filter and plug sufficiantly?<br /><br />Also, using 5W30 oil in that vehicle, may also cause high oil consumption.<br /><br />5W30 is a little thin for that application.<br /><br />I use 10W30 in my truck!<br /><br />Hope that helps.

 

[bluewater19]

Re: Where did the oil go.

Thanks for the quick replies.<br />I will check the oil cooler lines. The filter and plug were tight and I had no drips on the driveway. Do you think I should switch to a thicker grade of oil? What about mobile 1 20-50? I have been using castrol syntec but after reading what lubedude said about it I am pissed at them and I am switching all my cars to another brand. I have been using 5w30 because thats what the filler cap says. I use delo 15w40 in my older boat and I am planning on switching to synthetic in my 2003 boat this spring. What do you think about valvoline synthetic 15w40?

 

[LubeDude]

Re: Where did the oil go.

Thats right I do remember the oil caps saying that. Consumption will fall some with a 10W-30 though! and wont hurt anything. I would do it if it were me. To aswer your question about the 20W-50 Mobil1, First off they do not make a 20W-50, only a 15W-50 (I forgive you), If you tow with this vehicle, I would reccomend it, Otherwise you probably do not need it. Mobil1 makes a 10W-30 synthetic.<br /><br /> The ony synthetic in the 15W-40 I would reccomend is the Amsoil Diesel marine. Not because Im pushing it, but that its formulated for marine use.

 

[crab bait]

Re: Where did the oil go.

ask J B.. he posted the same post onetime ..