87 5.7L burning oil

[bennylava]

Looking for a little info on the oil burning these engines do. 87 TBI 350. There's no smoke coming out of the tailpipe. There's nothing leaking on the ground. But my truck burns a lot of oil. I always have to add about 4 quarts in total between each oil change. Seems like it might be more than that.

Would adding Lucas to the oil help me out any? I use Royal Purple 10w30. Maybe if I switched to 15w40 Rotella T, it wouldn't burn quite so much?

Any thoughts on what may be causing this? Besides needing a rebuild. Thanks!

[Nick_R_23]

There is mainly 4 ways to lose oil in an engine -

1. Leaking seal or gasket allowing oil to leak past.

2. Cylinder bore wear or worn/overheated rings allows oil past rings and into combustion chamber.

3. Worn valve guides or valve stem seals allow oil to be sucked past valve stem.

4. Faulty PCV valve or internal baffle allows oil residue to be sucked into intake tract.

There really is no magic fix for oil loss, unless it’s a simple PCV or gasket/seal replacement. Most new oils are smokeless formulas, and combined with a catalytic converter, you may not see visible smoke from burning oil.

[Ziegelsteinfaust]

Like above clean the pvc system or valve.

I would go to atleast a 20w50 or pour a couple of quarts of 40W in.

Your in Texas so winter starting of cold fluids is not the biggest issue.

[geezer#99]

You forgot #5.
Too much oil.
A extra quart can be splashed onto the cylinder walls overwhelming the oil rings. It’ll burn a little at a time. Just enough to burn a quart and not show up on the tailpipe.

[sick472]

I had the same problem with my 85. I did switch to 15w40 Rotella T with no noticeable difference, but left it that way since all my other vehicles use the same oil. I suspected my main problem was worn valves and guides as 3 of the 8 plugs would oil foul regularly. It recently jumped a tooth on the timing chain...it doesn't use any oil now (sitting on the shop floor)!

[Dead Parrot]

Total miles on engine?
Miles between oil changes?
How do the plugs look?

Just because little oil drips on the ground doesn't mean you don't have leaks. Some valve cover leaks happen over the exhaust manifolds and almost all of the oil will be evaporated off by the hot manifolds. You can lose a lot of oil out of bad valve cover gaskets.

Switching to a higher weight oil is a cover up, not a fix.

[Pontiac1976]

*** Dead Parrot

small bit of pull on the convertor when you tighten them to fly wheel.

when your engine is hot if it is burning oil you should smell it, The plugs and tail pipe are a big tell tail. Take the truck to a car wash power wash the motor but do not sprat the TBI or the electric parts ( intake near the valve covers, the valve covers, heads, back of the block top of the bell housing timing water pump, oil pan, and take a look under the TQ cover when it cold maybe the rear main seal leaking. Take for a good high way drive pull over keep it running sniff the motor & look all around ATT: very hot watch you touch if it leaking med to bad you on the the gasket you see it and smell it.
87 head valve guides after miles get up there may be bad. If you have the factory 87 heads still on never had the head valve seal replaced. It time ( you should see plugs tell tail there.) There is with age and miles the heads need to be freshen up. You do a compression test if the compression is really on the high side then rings should be ok if there a big drop from one to the other might have problems in those cylinders or head for the cylinder.

[52napco]

It's just worn out....put a replacement crate motor in it and be done

[THI]

I bought a new 1988 K20 Suburban and it burned oil from the day I bought it - valve guides. Since is used around a quart per 1,000 miles GM said it was normal! My 1985 K20 never used a drop.