Dirty oil after 900 miles

Hi all, I tried to search for any previous thread regarding my question but couldn't find anything.

This is probably a very general question or maybe a "depends" question:

I got my oil changed less than 900 miles ago and the oil is very dirty. It's a very dark brown and I even remember checking it at about 700 miles and it was pretty much the same -- very very dark brown.

It's lost probably about a pint since the oil change. The engine has 113,300 miles on it and it smokes on a cold start up but only for about 10 seconds; it doesn't smoke while idling/running.

As always, thanks.

Try High Mileage motor oil, it's probaby the detergent cleaning your engine.

Hi all, I tried to search for any previous thread regarding my question but couldn't find anything.

This is probably a very general question or maybe a "depends" question:

I got my oil changed less than 900 miles ago and the oil is very dirty. It's a very dark brown and I even remember checking it at about 700 miles and it was pretty much the same -- very very dark brown.

It's lost probably about a pint since the oil change. The engine has 113,300 miles on it and it smokes on a cold start up but only for about 10 seconds; it doesn't smoke while idling/running.

As always, thanks.

replace the PCV . make sure the crankcase vent system is working. make sure you have no vacuum leaks. check the air cleaner gasket on carb .

If the carb was adjusted it may be too rich.

pull plugs check all for burn / color..

these engines have poorly machined valve guides. this is why it will smoke on a cold start.

what oil are you using ? what filter ?

replace the PCV . make sure the crankcase vent system is working. make sure you have no vacuum leaks. check the air cleaner gasket on carb .

If the carb was adjusted it may be too rich.

pull plugs check all for burn / color..

these engines have poorly machined valve guides. this is why it will smoke on a cold start.

what oil are you using ? what filter ?The PCV is good (recently bought a new one) and it does seem to rattle like normal while the engine runs.

I think the crank case vent system was pretty good, it should be better now that I fixed up a valve cover.

I'm pretty sure I have no vacuum leaks and I have carefully replaced nearly all vacuum, emission, and fuel hoses (tediously) no less than a couple of years ago.

The air cleaner gasket looked okay but I got a new one anyway. The new one is nearly twice as thick and seems to seal far better.

I noticed what seemed to be evidence of a small oil leak in the right-side (passenger-side) engine valve cover. I got a new gasket (rubber), cleaned everything very well, checked the valve cover for straightness, and even added a bead of RTV sealant on it. The left valve cover was recently given a new gasket too and it was carefully installed and torqued; the left valve cover looks fine.

I think I had the carb running a little too rich a while back before the oil change but corrected it recently.

Among all of the spark plugs, the number 8 plug always gets very dirty within a short time (right-side near firewall). By a short time, I mean maybe 100 miles or so. I remember checking it recently and it was pretty bad (not brown, but black with oil). The rest of the spark plugs are usually fine (a little bit brown).

I paid to get this oil change done, they used Pennzoil 5W-30 and a Pennzoil oil filter.


I recently researched more on valve seals and I think I probably need new seals badly. I recall taking the intake manifold off a while back and I could see a TON of gunk and deposit on the valves (worse than pretty much any picture of an example I found online).

I plan on changing the valve seals before the end of the year, do you think this could be the cause?

Thanks for your input and time.

I think 5W 30 is too thin for an old tech, high mileage engine in the warm temps of Arizona. 10W 30 is more like it. Thicker oil would reduce your oil burning slightly.

As the above posts suggest, the oil is probably getting dirty because of considerable blow-by from the worn rings, cylinder wear, etc, and some existing deposits in the engine.

the #8 cylinder condition could mean low compression/valves worn/burn't. could also be bad plug wire. using a meter measure all plug wire resistance and compare. this should be 10k to 15,ooo ohm area.

the oil used should be 10-30wt. 5-30wt is good if your going into below 32 deg temps... ,,,, like where I live, arizona stay with the 10-30wt.

the valve seals may help..the real problem with smoke on start up is the valve GUIDES ...this would require removal of the heads, then a machine shop to correct this manufacturing defect that all these 305cu 80's engines have.

oil changes must be done when the engine is hot. if warm or cold the sludge is not going to come out. remove the valve covers and using a coat hanger / stiff wire make sure all the head drain back holes are clear.

most times the drain back holes at the back of the engine are restricted with sludge/carbon/ or even manufacturing dirt/gasket material .

this may be why it smokes and why #8 has a build up on plug.

I think 5W 30 is too thin for an old tech, high mileage engine in the warm temps of Arizona. 10W 30 is more like it. Thicker oil would reduce your oil burning slightly.

As the above posts suggest, the oil is probably getting dirty because of considerable blow-by from the worn rings, cylinder wear, etc, and some existing deposits in the engine.

At operating temps 10w-30 is NOT necessarily thicker than 5w-30. At a cold start yes a 10w-30 is thicker but at operating temp is is very possible for even a 0w-30 to be thicker than either of these. All three are 30weight at operating temp and 30 weight is a RANGE.

I have not checked recently but at one point M1 10w-30 was one of the thinnest anything "_w-30" oils you could buy and Castrol Syntec 0w-30 was one of the thickest. But that flies in the face of what everyone "knows" about oil.
Would require some effort but here is where you can sort out the myths from the facts.
http://www.bobistheoilguy.com/cms/

At operating temps 10w-30 is NOT necessarily thicker than 5w-30. At a cold start yes a 10w-30 is thicker but at operating temp is is very possible for even a 0w-30 to be thicker than either of these. All three are 30weight at operating temp and 30 weight is a RANGE.

I have not checked recently but at one point M1 10w-30 was one of the thinnest anything "_w-30" oils you could buy and Castrol Syntec 0w-30 was one of the thickest. But that flies in the face of what everyone "knows" about oil.
Would require some effort but here is where you can sort out the myths from the facts.
http://www.bobistheoilguy.com/cms/


I GOT THIS DIRECTLY FROM THE 1984 OWNERS MANUAL..

5-30wt oil is for -20deg f to 80deg f ...this summer a large part of arizona had 110 deg plus temps !

10-30wt 0 deg f to 100 deg plus..

30wt 40deg f to 100 plus...

after reading these ancient directions in a hot climate I would use 30wt..

this would give the best lubrication in a hot climate..

in mesa az it is not below 40deg f for very long , maybe a few hours from time to time..

I am tickled by the reference to that web site. I was banned from that site after asking technical questions (via private email, not in the forum) about tribology. It seems that chemical engineers are in very short supply at his former employer. Worse yet, this guy is (was?) a sales rep for Schaeffer in Florida - Not a degreed chemical engineer nor tribologist, but a salesman. I asked why their products are not used or advised by the largest manufacturer of hydraulic equipment in the known universe (for whom I was an engineer). I particularly asked about his opinion regarding the validity of their well-touted "ball test" or "Timken test" for measuring a lubricant effectiveness and why they are about the only ones who use it to market their junk, err, products for applications not requiring EP lubricants. After pointing out the irrelevancy of that test in the application and asking for empirical data instead of conjecture and testimonials in lieu of science, the only response I received was that I was banned from that site and mail was rejected.

Giving credit where credit is due, the marketing is genius. Search for the market where the customers are the least educated, most gullible, and are more free with their spending that any business would ever be. That would be the automotive lubricant market. Everyone uses it, and almost no one knows anything of any consequence about it. This salesman identified that market and exploited it. Credit due, for sure, for that realization. That same market has seen many incursions by others trying to separate people from their money through less than scientific “evidence” and clever deception. The U.S. FTC has taken to court and secured either settlement, Summary Ruling, Consent Order, or other means of cessation or other concession from numerous manufacturers of automotive oil additives such as TMT, Pro-Long, Z-Max, Dura-Lube, Motor-Up, Slick 50, and hoards of others. This has been done since the ‘80s, but the abundance of ignorance of the consumer base is so tempting that many companies till try to pump this market for all the cash it can give up. This includes additive sellers and oil sellers alike. One of the BIGGEST mistakes the FTC has made, however, was in allowing Group III mineral oils to be labeled and sold as “synthetic” since many of us who were using synthetics in the 1970s understood the huge difference. If a turbocharged Dodge Neon accelerates as fast as a Ferarri, we still can’t sell a Dodge Neon under a Ferarri name because by all other metrics it’s still a steaming POS. Unfortunately, the FTC didn’t see it that way.

I had pointed out (evidenced from internet content on other sites as early as 1999 - Years before they started using the data) the SAE/SSU comparison was all but meaningless in an engine or hydraulic pump/motor application. They have since proudly exclaimed how the SAE system they had previously espoused themselves to isn’t relevant. That previous inquiry was probably dismissed as some idiot (me) on the internet thinking he knows more than a salesman. Magically, that comparison is now held up in their highest regard on the oil site.

REAL lubricant manufacturers have better and more available data. REAL lubricant manufacturers actually MAKE their own base stocks. REAL salesmen know their product lines and the strengths and weaknesses. I think I must have struck a nerve with my technical questions.

Incidentally, I’m giving a deposition in one case on Monday morning, and I’ll be in court next week taking a different fool’s money. One more case in the backlog doesn’t scare me.

In any event, synthetics (particularly PAO and POE) don’t play the “multi-viscosity’ game like mineral oils with polymers. Some day, some well-referenced web site may even post that up as “knowledge” they invented. Since the FTC decided not to protect us, Caveat Emptor (let the buyer beware).

In short (or is it too late for that?) use the lubricant with the correct viscosity (Saybolt, not SAE) for the application at full operating temperature and try to select one with the lowest pour and pumping points anticipated. I think you can find references to that I've made here and elsewhere for years. I might be wrong, but at least I'm consistent. ;)

And it isn't just me. The head man at Schaeffer ITSELF downplays the validity of what I questioned years ago:

For more info on the use of the Timken EP test, reference this article from Machinery Lubrication magazine, written by Mr. Ludwig, Chief Chemist/Tech Director of Schaeffer.

From this article: "Any test results that are obtained by the use of this test method have been found not to correlate with results obtained during field service."

http://www.machinerylubrication.com/Read/616/gear-drive-lubricants

the #8 cylinder condition could mean low compression/valves worn/burn't. could also be bad plug wire. using a meter measure all plug wire resistance and compare. this should be 10k to 15,ooo ohm area.

the oil used should be 10-30wt. 5-30wt is good if your going into below 32 deg temps... ,,,, like where I live, arizona stay with the 10-30wt.

the valve seals may help..the real problem with smoke on start up is the valve GUIDES ...this would require removal of the heads, then a machine shop to correct this manufacturing defect that all these 305cu 80's engines have.

oil changes must be done when the engine is hot. if warm or cold the sludge is not going to come out. remove the valve covers and using a coat hanger / stiff wire make sure all the head drain back holes are clear.

most times the drain back holes at the back of the engine are restricted with sludge/carbon/ or even manufacturing dirt/gasket material .

this may be why it smokes and why #8 has a build up on plug.

I tested the compression about 6mos ago and all seemed good (and with minimal differences between each cylinder and pairs of cylinders. However, perhaps another check is in order.

I think the wires are all good and they are only about 3 mos old; I'll check them nonetheless as well.

I was afraid you were going to mention the valve guides :frown: I think it may be best for me to save my money up for a remanufactured 350 instead. I will replaced the valve guide seals anyways for the sake of it at least hopefully helping to lessen the problem (and the learning experience).

I had no idea that oil changes were supposed to be done with the engine hot! I will make sure that I have the engine at full-operating temp next time.

I will check the drain holes and do the aforementioned before the end of the year, thanks.

I GOT THIS DIRECTLY FROM THE 1984 OWNERS MANUAL..

5-30wt oil is for -20deg f to 80deg f ...this summer a large part of arizona had 110 deg plus temps !

10-30wt 0 deg f to 100 deg plus..

30wt 40deg f to 100 plus...

after reading these ancient directions in a hot climate I would use 30wt..

this would give the best lubrication in a hot climate..

in mesa az it is not below 40deg f for very long , maybe a few hours from time to time.. Thanks for the input, I'll use 10w-30 next time. I would think, for at least the time being, it's okay to stick with the 5w-30? It hasn't reached 80 degrees lately and it does occasionally get below freezing (recently we reached a low of 26 F, I was out at that time and I never want to experience that or lower again). :tongue:

@ Blue Bowtie: I read your replies and it was very interesting although some parts were hard for me to fathom. I hate being ignorant about any product I buy (especially for my car) because I hear of so many "snake oil" products, not just limited to car fluids... And dishonest manufacturers really upset me because I want what I'm buying to be the right thing for my car... Anyways besides that, I hope I mostly understood what you were saying.

In short (or is it too late for that?) use the lubricant with the correct viscosity (Saybolt, not SAE) for the application at full operating temperature and try to select one with the lowest pour and pumping points anticipated.But what if the oil filler cap calls for an API class of oil? The original (as fair as I know) oil filler cap says "Use energy conserving SF, SF/CC or SF/CD oil" I've always just used 5w-30 or 10w-30.

Thanks for your help and input guys.

It's not so much the guides - I really won't expect a 103k mile engine to have worn guides - but what I do think is up with your puff of smoke is the valve guide seals. These are neoprene O-rings, which tend to dry out and get brittle over time. Once they become brittle, they're no longer good as seals. This is a common issue with higher mileage SB engines, nothing serious. Your oil consumption with this malady will increase a tablespoon or two between oil changes.

I have found that Shell's Rotella-T 15w40 oil works great out here in the summertime Valley heat.

since you are in winter the temps will be below 80deg for a time now..

you could get snow this year the way things are going out you way..

I would remove the valve covers and inspect and ram out those drain back holes and clean up any sludges/carbon on the top of the head...

if you find lot of crud after cleaning place 5 oz of marvel mystery oil to the crankcase and run for 200mi then change the HOT oil...you may notice an improvement in lowering engine noises...

you may have to repeat this if very sludged but over time it will be captured by the oil filter..

since you are in winter the temps will be below 80deg for a time now..

you could get snow this year the way things are going out you way..

I would remove the valve covers and inspect and ram out those drain back holes and clean up any sludges/carbon on the top of the head...

if you find lot of crud after cleaning place 5 oz of marvel mystery oil to the crankcase and run for 200mi then change the HOT oil...you may notice an improvement in lowering engine noises...

you may have to repeat this if very sludged but over time it will be captured by the oil filter..

Will do. Few days back I had a family emergency and had to hurry to the hospital. There was a lot of 80+mph cruising and high speed passing. It was about 15 miles to he hospital. When I had the time to check the oil later I lost almost a pint of oil just from that... I'm hoping it's just the valve covers and that I need to check the seal...

How about the age!
Valve stem seals(rubber) causing burning more oil, and PCV + EGR gases being recycled.

I GOT THIS DIRECTLY FROM THE 1984 OWNERS MANUAL..

5-30wt oil is for -20deg f to 80deg f ...this summer a large part of arizona had 110 deg plus temps !

10-30wt 0 deg f to 100 deg plus..

30wt 40deg f to 100 plus...

after reading these ancient directions in a hot climate I would use 30wt..

this would give the best lubrication in a hot climate..

in mesa az it is not below 40deg f for very long , maybe a few hours from time to time..



This is why forums are so drastically lacking in QUALITY posters. Raging imbeciles that think 25yo "data" applies I get it you are a stupid :jerking: not intelligent enough to be helped or even let anyone else help others.

FEW guys with a clue are willing to argue with morons like you, sucks for the people who need help.

Blue, did not mean to say that forum was 100% nothing on the internet is. On it though you can look at oil analysis and compare CST @ 100C(viscosity at 212degrees Fahrenheit) for various weight of oils and see what I am talking about far as a 10w-30 can easily be thinner at operating temp than even a 0w-30. At least with modern oils. Maybe jcat has some 25+yo oil he prefers to use though.

This is why forums are so drastically lacking in QUALITY posters. Raging imbeciles that think 25yo "data" applies I get it you are a stupid :jerking: not intelligent enough to be helped or even let anyone else help others.

FEW guys with a clue are willing to argue with morons like you, sucks for the people who need help.

Blue, did not mean to say that forum was 100% nothing on the internet is. On it though you can look at oil analysis and compare CST @ 100C(viscosity at 212degrees Fahrenheit) for various weight of oils and see what I am talking about far as a 10w-30 can easily be thinner at operating temp than even a 0w-30. At least with modern oils. Maybe jcat has some 25+yo oil he prefers to use though.


the reason I enjoy these forums is because of Raging imbeciles like you ! too boring other wise !

you have all the engineering data and spec's for a 1984 gm 305 engine ...you make it all up in your mind .

these fluid manufactures are always making unreal claims .