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Old 12-02-2008, 09:06 AM   #1
oirebit84
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Burning oil

Hey guys. I have an 87 GMC R1500 with a 305. The engine runs so well but it uses about a quart of oil every 300-400 miles. I know the proper thing to do is to replace the engine with a 94 350 i have, but i just don't have the funds to do it the way i want now. i don't wanna half ass it. is there anyway to stop or reduce the amount of oil it burns without harming the engine? It doesn't smoke on startup so i don't think it is the valve seals. you can see a little blue haze behind the truck as i go down the road. so i think it could be rings. If so can i use thicker oil? one of my dads friends told me that you could use 15w-40 and it would stop it from using oil, but could i use that without harming the engine? or even 10w-40 instead of 10w-30? Thanks Guys!! This forum rocks!
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Old 12-02-2008, 10:15 AM   #2
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Re: Burning oil

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Originally Posted by oirebit84 View Post
Hey guys. I have an 87 GMC R1500 with a 305. The engine runs so well but it uses about a quart of oil every 300-400 miles. I know the proper thing to do is to replace the engine with a 94 350 i have, but i just don't have the funds to do it the way i want now. i don't wanna half ass it. is there anyway to stop or reduce the amount of oil it burns without harming the engine? It doesn't smoke on startup so i don't think it is the valve seals. you can see a little blue haze behind the truck as i go down the road. so i think it could be rings. If so can i use thicker oil? one of my dads friends told me that you could use 15w-40 and it would stop it from using oil, but could i use that without harming the engine? or even 10w-40 instead of 10w-30? Thanks Guys!! This forum rocks!
As I understand it there can be other sources of oil being burned than just the valves or the rings. Have you checked the PVC vale to be sure that it is working properly(it should rattle). Have you noticed a lot of oil in air cleaner breather for the PVC that would be a give away. Are you leaking any oil? Have you noticed any fouling on the plugs? Do you do a lot of Highway driving with a tall rear gear? Have you done a compression test if so what was it?
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Old 12-02-2008, 10:54 AM   #3
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Re: Burning oil

my 81 gmc K-10 with a rebuilt caprice 350, burns oil, but, i changed the oil in it last weekend and i poured in a can of Lucas oil stabilizer, my uncle recommended Restore but we got both and ive watched on startup a few times and noticed a big decrease in smoke, ill keep an eye on it and be back with details.

Last edited by BREIT1; 12-02-2008 at 11:40 AM.
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Old 12-02-2008, 01:18 PM   #4
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Re: Burning oil

Sometimes the brand of oil makes a difference. I had an old 350 that I was running Kendahl oil in that smoked really bad. I switched to Valvoline and the smoke almost stopped. Just an idea. I would try a compression or leakdown test, pcv, valve cover and intake gasket leaks too.
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Old 12-02-2008, 05:19 PM   #5
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Re: Burning oil

I've used Valvoline MaxLife oil which is a blend for high mileage motors and it did reduce consumption by a noticeable amount. If you can get it down to a quart every 1000 miles, that would be acceptable. Try 10W-30 first and see what it does.

As a side note, avoid Fram oil filters. WIX or Purolator is the way to go.
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Old 12-02-2008, 05:28 PM   #6
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Re: Burning oil

Same truck that I have but I know that my valve seals are gone. It does not smoke going down the road But as soon as I get on the gas wow great fogger though. I bought some umbrella valve seals for it that I plan to put on this winter some time. I would check the PCV valve and the breather on it. If it were rings you would be fowling your plugs I would think that the rear main seal would be blown if anything.

If it were me I would by a can of sea foam. Run it for 15min to 30 min max and then change the oil This will clean any rings that may be sticking and also clean all vacume ports as well in the engine. JMO
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Old 12-02-2008, 09:15 PM   #7
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Re: Burning oil

I'm not sure if my burb was burning oil because I just got it but the oil that was in it did smell burnt. I flushed the oil system out with a gunk remover, dropped the pan and cleaned the sludge and added new oil. I also added a can of restore and gained 15 pounds of oil pressure while accelerating and 5 while idling.

My guess is that the gunk stuff unstuck some of the rings because after 250 miles the oil doesn't smell burnt anymore. You might want to try it.
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Old 12-02-2008, 09:15 PM   #8
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Re: Burning oil

Will that can of seafoam start new leaks? I've found that older engines are held together with the sludge that builds up in them. lol. I haven't checked the pcv valve or the breather. i'll check and get back to you guys. You say the lucus oil stabilzer helps eh? I'll try that next change. thanks guys!
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Old 12-02-2008, 09:24 PM   #9
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Re: Burning oil

I have the same problem as well but my problem is i have worn rings. I use a thicker oil (20-50w) and also use a hotter spark plug #26 rather than #24 to slow down the fouling of my plugs. That makes things a little better. I also use the lucas oil stabilizer too.

Last edited by shrtbx; 12-02-2008 at 09:28 PM.
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Old 12-02-2008, 09:59 PM   #10
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Re: Burning oil

No oil leaks on mine after using the gunk stuff...but just figured out that I got a blown head-gasket to repair

It ammazes me how stupid some people really can be. I got my suburban from a used car lot and the guy said that it sat the whole time (why he didn't just start it up once a week I will never know...cuz of it sitting I now have a blown head-gasket and just finished swapping in a rebuilt tranny that blew because of a stuck valve because it was sitting.)

But at least my oil isn't leaking anywhere

Please do not try to by-pass the site's filters by mis-spelling banned words.

Last edited by LONGHAIR; 12-12-2008 at 07:15 PM. Reason: Language
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Old 12-04-2008, 07:43 PM   #11
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Re: Burning oil

Thanks guys. i'll try the seafoam stuff before i change the oil. But i'm still wondering if a thicker oil will help? and what the pros and cons are. would 20w-50 be too thick? a guy I work with says he has and is running 20w-50 in all his 350's and a 305. What do ya think?
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Old 12-05-2008, 02:56 AM   #12
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Re: Burning oil

Yo!
Hell, we used to use a product called STP way back when! It was of the viscosity of honey! A pint of that in the crankcase and old engines seemed to perk up to nearly new performance.
I don't know if THAT's the proper solution, but I DO know that you could run 10W-40 without any problems and reduce some burning and leaking of oil. 10W-30 was designed to reduce gas consumption. I run 10W-40 in all my vehicles, new and old, because I like the engine protection. I run Castrol in my high performance engines because it resists heat breakdown better.
NAPA oil is made by Ashland Oil (which is Valvoline, but is cheaper) and is of very high quality. My FRANKENTRUCK is being broken-in on 10W-40 NAPA, and then will run on 10W-40 Castrol due to it's 350hp/411ft lb torque 350 V8, just like my Camaro's.
You didn't mention if you were leaking any oil,...most older engines develop oil pan gasket leaks, rear main leaks, rocker cover leaks, etc,...but maybe yours has done well and the surface under where it parks is oil free.
And, if you haven't, check the tune and carb adjustment. Just being out of tune can cause greater oil consumption and visible output as you go down the road.
Seafoam is great stuff for many purposes,...I use it for fuel stabilizing and carb maintenance, but it has many other uses and works quite well!
Best of luck!
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Old 12-05-2008, 03:03 AM   #13
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Re: Burning oil

FYI: my '72 VW Superbeetle has a new GEX engine with special order hydraulic valves and is recommended to run on 20W-50. Sure seems like that may be feasable in a V8 if the opposed 4 can do it. Todd.
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Old 12-05-2008, 02:53 PM   #14
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Re: Burning oil

20w-50 is thick oil and does not flow well when cold. (I will not start my Harley when the temp is below 40 degrees. 20w-50 synthetic). I would not recomend running 20w50 in your truck during a winter in the north.
The reason air cooled engines (ie. VW, Harley) run thicker oil is because they run hotter. Harley recomends running lighter oil for winter. I believe 10w30.
Seafoam is great stuff for cleaning up an engine of fuel systems.

Have you done any of the tests or inspections on it yet? Compression? Check pcv?
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Old 12-05-2008, 03:36 PM   #15
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Re: Burning oil

Back in high school, I had an original 350 in a Chevelle with 100k+ miles on it. Drove 60 miles a day & raced it in the bracket street class every weekend (it had a hard life). Added a quart & half of oil (Delo 15/40)every week, put that STP motor honey stuff in at every oil change, & went one number hotter on the plugs. Ran it like that for 3 years and sold it to a guy who put it in a hunting truck & he ran it for 2 more years
So, in my opinion, burning some oil isn't all that bad. Hell, it could run 5 more years with no problems as long as you keep it checked.
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Old 12-06-2008, 01:24 AM   #16
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Re: Burning oil

You have to remember that some of these older engines are actually meant to burn some oil.
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Old 12-06-2008, 03:12 AM   #17
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Re: Burning oil

All engines burn some oil, and as they get older, and tolerances get larger, they burn more oil. Properly maintained, the usual initial failure is seals, causing the leakage of oil. Todd.
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Old 12-12-2008, 10:18 AM   #18
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Re: Burning oil

the smoke on start up has gone down quite a bit, i haven't checked my oil in a while which i will be doing tonight along with all my other fluids.
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Old 12-12-2008, 10:38 AM   #19
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Re: Burning oil

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the smoke on start up has gone down quite a bit, i haven't checked my oil in a while which i will be doing tonight along with all my other fluids.
Engines that sit for long periods outdoors will develop rust on the bores of the cylinders with open vales allowing oil to blow by the rings. Think I'm kidding? Just washing my car will cause the rotors to develop a rust scale.
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Old 12-29-2008, 03:59 PM   #20
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Re: Burning oil

It may just be your valve stem seals . Mine did the same, i just threw on some new heads and it was good
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Old 12-29-2008, 04:41 PM   #21
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Re: Burning oil

10w40 in the winter and 20w50 in the summer... I'm the king of driving some wore out ****... just remember with 20w50 in it the motor has to work harder to push around all the thicker oil so dont rev it to the sky alot.
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Old 12-30-2008, 03:15 PM   #22
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Re: Burning oil

Hay guys. I'll make this short. I've been running Mobile 1 in mine for years because I read something back then. Seems that some of the Italian car makers (you know the ones with half million $ price tags) Will NOT honor the warrentee if you use anything else but Mobile 1. I run the 20-50 all year round and it has never failed to start and oil consumption about 1 quart every 1500 to 2000 miles. I change the oil every 5000 to 6000 miles depending on use. I also run a 5 quart pan not 4 qt and a 2 quart filter. It's expensive but it's good and dependability is the bottom line. jim
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Old 12-30-2008, 03:29 PM   #23
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Re: Burning oil

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Originally Posted by James McClure View Post
Hay guys. I'll make this short. I've been running Mobile 1 in mine for years because I read something back then. Seems that some of the Italian car makers (you know the ones with half million $ price tags) Will NOT honor the warrentee if you use anything else but Mobile 1. I run the 20-50 all year round and it has never failed to start and oil consumption about 1 quart every 1500 to 2000 miles. I change the oil every 5000 to 6000 miles depending on use. I also run a 5 quart pan not 4 qt and a 2 quart filter. It's expensive but it's good and dependability is the bottom line. jim
Got any pictures of that two quart filter that must be a bigun! Where do you get them?
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Old 12-30-2008, 03:37 PM   #24
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Re: Burning oil

Bob: You can get the filters from NAPA or from your local Chevy store. jim
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Old 12-31-2008, 11:47 AM   #25
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Re: Burning oil

Hey Guys! Thanks for all the suggestions. I've tried them and am running 10w-40 in the engine but she still smokes. I noticed it fouled the number 1 spark plug, so i did a compression check and all the cylinders have around 160psi except the number one cyl has 80psi. is it normal for when i take the oil cap off with it running, it puffs like a locamotive. is that normal? Thanks guys!
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