dirty oil. Why so quick

N

nbrskn

Senior Member
I have an 8BA . Recently rebuilt. Since rebuild it doesnt take but a few short miles before the oil is dirty. 30 miles one time .this time from replaceing bad head 100 miles. Had pan off and black stuff in pan.
Any ideas? New carb from Dennis carpenter this last 100 miles.
Engine runs good and is pepppy. Compression runs 110 across all 8 cyl.
Had PVC on it and took it off and put road tube back on .
did not make any dif.

Thanks
 
It doesn't have a full-flow oil filter. Back in the day the regular interval for oil changes was 1000 miles. I remember Kendall Motor oil advertising that it was the "2000 Mile Motor Oil". Henry (and others) believed that the way to keep your engine clean was to change the oil frequently.
 
Has the engine been on the road long enough with enough miles for the rings to seat?

Additives in oils are designed to literally "clean" so the oil will get dirty pretty quick.
 
nbrskn said:
I have an 8BA . Recently rebuilt. Since rebuild it doesnt take but a few short miles before the oil is dirty. 30 miles one time .this time from replaceing bad head 100 miles. Had pan off and black stuff in pan.
Any ideas? New carb from Dennis carpenter this last 100 miles.
Engine runs good and is pepppy. Compression runs 110 across all 8 cyl.
Had PVC on it and took it off and put road tube back on .
did not make any dif.

Thanks
Click to expand...
'recently rebuilt'...if original type rings, may not be seated yet ? If not seated yet, gas can/will pass by rings...and contaminate oil ! If you do not have an oil filter, oil has to catch and retain all by products of combustion.
Are you using multi-grade oil ? That is doing its job and keeping crankcase clean. If no filtering system, change whatever oil you use often enough to Ford specs.
 
DD931 said:
It doesn't have a full-flow oil filter. Back in the day the regular interval for oil changes was 1000 miles. I remember Kendall Motor oil advertising that it was the "2000 Mile Motor Oil". Henry (and others) believed that the way to keep your engine clean was to change the oil frequently.
Click to expand...

Interestingly, the original "Service Data Handbook" that came with my '40 specifies that the oil "be changed every 2,000 miles" for cars without an oil filter. For cars with an oil filter it states "that the oil be changed at 5,000 mile intervals. The filter should be replaced every 10,000 miles."
So Henry thought differently than we think he thought!

Now the kicker: The book also states "except for seasonal changes."
 
Older engines with carburetors don't have near the efficiency in the fuel delivery system as the modern electronically controlled fuel injection. With new rings seating in as well, the combustion by products get into the oil pretty quick. The first 500 miles or so should be enough to bed things pretty well so an oil change is critical in that phase. From that point on the normal service interval would be in effect.

This is the way they always were so there isn't much that can change that other than fabricating a late type fuel injection system for it.
 
40 Deluxe said:
Interestingly, the original "Service Data Handbook" that came with my '40 specifies that the oil "be changed every 2,000 miles" for cars without an oil filter. For cars with an oil filter it states "that the oil be changed at 5,000 mile intervals. The filter should be replaced every 10,000 miles."
So Henry thought differently than we think he thought!

Now the kicker: The book also states "except for seasonal changes."
Click to expand...

My 36 air leaner says 1000 miles or sooner if xxxxxxx . The rest was gone from the decal . Sorry
 
engine was rebuilt by a reputable shop. Has a full flow oil system from Mark Kerby. Has an oil filter. Has 10w40 oil . Pennzoil. Engine has a little over 2000 miles on it.
 
There used to be a lot of oils that would turn black as they get hot - used to be a way for the manufacturer to increase oil changes. What I don't know is which oils actually do this today? One thing to think about is having the oil sent/tested at a lab - they can tell you what shape the oil is in. Me - I just run Penn Grade 'green oil' . . . tends to stay green and I change it about once a year . . . whether it needs it or not. :)
 
Not sure about the current Pennzoil, but in the past it was a high sulfur oil. I have had (again in the past) a lot of bad experiences with Pennzoil and tend to stay far away from it. Some of the dirtiest engines I ever took apart had been using it.
 
i am 75 year young. Been using pennzoil all my life. Have rebuilt many of my vehicles engines. All were clean inside. Must be regular oil changes.
336000 1978 F150 , 226000 1968 F150 , 200000 1967 Galaxie 500 of which still own, 196000 2002 lincoln that I still own. thats Just a few
 
nbrskn said:
i am 75 year young. Been using pennzoil all my life. Have rebuilt many of my vehicles engines. All were clean inside. Must be regular oil changes.
336000 1978 F150 , 226000 1968 F150 , 200000 1967 Galaxie 500 of which still own, 196000 2002 lincoln that I still own. thats Just a few
Click to expand...

Sure not my experience!
 
Years ago it was common belief in my part of the world that Quaker State would sludge an engine. I wasn't a mechanic and didn't see any of the evidence but I didn't use it. It might have been from the base crude that came from Pennsylvania. Today, with modern refining and crude coming from all over, it could be different.
 
on this topic...is there a way to reduce the oil burn from the exhaust without rebiuilding the entire engine?
 
Break-In Period: It's common for oil to become dirty during the break-in period of a newly rebuilt engine. During this time, residual machining debris, assembly lubricants, and other contaminants may get circulated within the engine, leading to increased oil contamination. It's advisable to change the oil and filter after the initial break-in period, typically after the first 500-1000 miles, to remove these contaminants.
 
Blow by would be my guess. Change the oil sometimes. It'll get dirty. Drive it if pressure is good or above 0. It's not going to be clean forever. maybe put a filter on it if worried.


Not sure how you get a bad head...
 
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