The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1973 - 1987 Chevrolet & GMC Squarebody Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 08-05-2021, 09:30 AM   #1
bennylava
Registered User
 
bennylava's Avatar
 
Join Date: Jul 2017
Location: Texas
Posts: 408
87 5.7L burning oil

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!
bennylava is offline   Reply With Quote
Old 08-05-2021, 10:50 AM   #2
Nick_R_23
Registered User
 
Nick_R_23's Avatar
 
Join Date: May 2016
Location: Willow, Alaska
Posts: 881
Re: 87 5.7L burning oil

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.
Nick_R_23 is offline   Reply With Quote
Old 08-05-2021, 10:56 AM   #3
Ziegelsteinfaust
Registered User
 
Join Date: Dec 2012
Location: Temple City
Posts: 3,628
Re: 87 5.7L burning oil

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.
Ziegelsteinfaust is offline   Reply With Quote
Old 08-05-2021, 11:01 AM   #4
geezer#99
Registered User
 
geezer#99's Avatar
 
Join Date: Aug 2009
Location: Bowser
Posts: 13,732
Re: 87 5.7L burning oil

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.
geezer#99 is offline   Reply With Quote
Old 08-05-2021, 02:09 PM   #5
sick472
Registered User
 
sick472's Avatar
 
Join Date: Jul 2015
Location: Sedalia Mo.
Posts: 1,131
Re: 87 5.7L burning oil

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)!
__________________
He who is without oil shall throw the first rod. Compressions 8.7:1

1972 C10
1976 C10 (parts truck)
1985 K20
sick472 is offline   Reply With Quote
Old 08-05-2021, 04:07 PM   #6
Dead Parrot
Registered User
 
Join Date: Aug 2012
Location: Oklahoma City, OK
Posts: 2,611
Re: 87 5.7L burning oil

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.
Dead Parrot is offline   Reply With Quote
Old 08-06-2021, 11:57 AM   #7
Pontiac1976
Registered User
 
Pontiac1976's Avatar
 
Join Date: Oct 2015
Location: Ottawa, Ontario, Canada
Posts: 766
Re: 87 5.7L burning oil

*** Dead Parrot
Quote:
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.
__________________
1977 REG cab Long Bed with a 1984 Front Clip, 82 305 .60 over 9.0.1 flat top pistons, 4bbl, TH350, w/84 SS-intake & cam , w/ 1977 big block rad, 1975 gear box, 1984 master w/ metric fittings top & SAE fitting @ portion block, 1975 3.42 gear open diff. Duel 77-87 Factory air cleaner, duel inlet from rad support . Down sized 9' to new 8' Steel flat bed
Was a 77 454 w/308 gear. Taken out 550 lbs. up front with motor clip change.
Pontiac1976 is offline   Reply With Quote
Old 08-07-2021, 07:09 AM   #8
52napco
Registered User
 
Join Date: Jun 2014
Location: upstate sc
Posts: 2,095
Re: 87 5.7L burning oil

It's just worn out....put a replacement crate motor in it and be done
52napco is offline   Reply With Quote
Old 08-11-2021, 03:29 PM   #9
THI
Active Member
 
THI's Avatar
 
Join Date: Jan 2017
Location: Traverse City, MI
Posts: 195
Re: 87 5.7L burning oil

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.
THI is offline   Reply With Quote
Reply

Bookmarks


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 09:06 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com