351 C oil pressure issue

[WBofTN]

Phil:
I'm new to the cobra world. I bought a used Unique
427sc 2 months ago. My question is a/b not going by
the mark on the dip stick for your oil level.
My set up: 351W, oil cooler and duel romote filters (large Mobile filters). I recently changed oil and put
approx 6 qts in to bring it up to the mark on the dip
stick.
Q: Am I putting enough oil in / will to much cause damage?
My thoughts were the that the oil level in the
pan should be the same with or with/out an oil cooler.
Am I wrong?
This motor is very tricked out and only has a/b 700 miles on it. I Don't want to screw it up on account of
my ignorance. Also The former owner only used Mobil
synthetic 20w50. So I have stuck with that ($65 oil change).
Wes

'93 Unique 427/351W/4sp

[souzape]

Wes- if you have a Canton or other aftermarket oil pan you will need at least 8 qts of oil (probably 9 with dual filters). The driving factor is the oil pan capacity. If it's a stock 351W pan then 6 or7 is probably enough. Who built the engine? If it came from Southern Automotive it almost certainly has the Canton pan. The first thing you need to do is talk to the original owner and get the details from him. PHIL

[souzape]

Wes- if you have a Canton or other aftermarket oil pan you will need at least 8 qts of oil (probably 9 with dual filters). The driving factor is the oil pan capacity. If it's a stock 351W pan then 6 or7 is probably enough. Who built the engine? If it came from Southern Automotive it almost certainly has the Canton pan. The first thing you need to do is talk to the original owner and get the details from him. PHIL

[WBofTN]

Phil:
My engine is not SA built. The pan is a aftermarket
pan, but looks to be close to stock. The point to my
question was, no matter what pan you have - shouldn't
the oil level be the same? and anything over the full
mark - would indicate the oil level is too high.
I just want to make sure I running enough oil.

Wes

'93 Unique 427/351W/4sp

[WBofTN]

Phil:
My engine is not SA built. The pan is a aftermarket
pan, but looks to be close to stock. The point to my
question was, no matter what pan you have - shouldn't
the oil level be the same? and anything over the full
mark - would indicate the oil level is too high.
I just want to make sure I running enough oil.

Wes

'93 Unique 427/351W/4sp

[JerryBP]

The oli level should be just below the windage tray or the lowest point that the crank/rod caps come down into the oilpan so as to not create a lot of froth, stock dipsticks are usually too short thus causing the overfiling of deeper custom pans. Jerry

Work in Progress Unique 427-9429 400hp 351C Tremec 5spd by Bruce, Greg & Jerry Porter

[JerryBP]

The oli level should be just below the windage tray or the lowest point that the crank/rod caps come down into the oilpan so as to not create a lot of froth, stock dipsticks are usually too short thus causing the overfiling of deeper custom pans. Jerry

Work in Progress Unique 427-9429 400hp 351C Tremec 5spd by Bruce, Greg & Jerry Porter

[souzape]

Wes- the pan and the dipstick are two entirely differenct issues. My engine has a stock dipstick and an aftermarket pan. It too says it is full at 6 quarts but that is not possible because of the relationship between the bottom of the pan, the oil pick-up for the pump, and the dip stick. My pan is a different shape than stock and therefore the relationship between the factors mentioned above are different. In your case, as long as you are maintaining constant, acceptable oil pressure you are probably OK....in my case I am not and am therefore trying to figure out why. (Too much oil can cause the oil to foam in the pan due to the stirring action of the crankshaft which can also cause oil pressure to drop and be just a bad as low oil level) Your point would be correct if all pans were exactly the same depth...sadly this is not always the case. The critical relationship regarding proper indication is between the oil pick up and the full mark on the stick. Also, if you oil draining back into the pan from lines going to external accessories (e.g. oil cooler and/or filter) you may get an erroneous indication when the engine is static. PHIL

[souzape]

Wes- the pan and the dipstick are two entirely differenct issues. My engine has a stock dipstick and an aftermarket pan. It too says it is full at 6 quarts but that is not possible because of the relationship between the bottom of the pan, the oil pick-up for the pump, and the dip stick. My pan is a different shape than stock and therefore the relationship between the factors mentioned above are different. In your case, as long as you are maintaining constant, acceptable oil pressure you are probably OK....in my case I am not and am therefore trying to figure out why. (Too much oil can cause the oil to foam in the pan due to the stirring action of the crankshaft which can also cause oil pressure to drop and be just a bad as low oil level) Your point would be correct if all pans were exactly the same depth...sadly this is not always the case. The critical relationship regarding proper indication is between the oil pick up and the full mark on the stick. Also, if you oil draining back into the pan from lines going to external accessories (e.g. oil cooler and/or filter) you may get an erroneous indication when the engine is static. PHIL

[K.Wilson]

Wes,
If the oil dip stick and dipstick tube are stock and mounted in the stock locations you should use the dip stick reading as the guide as to what the oil level should be; no more oil than the full mark and no less than the add mark with the engine off and at normal operating temp. It does not make any difference how many filters, oil coolers, feet of oil line, or size of oil pan you have, full equals full!

Now if the engine does not have the original equipment dip stick or tube or if they are in a different location that is another problem, and the dip stick must be calibrated to that engine.

Overfilling is just as bad as no oil at all. When over full, the oil can come into contact with the rotating crankshaft; this will cause the oil to "froth" or foam-up like laundry soap so the liquid oil level is decreased and there is nothing for the pump to pick up. Kind of like trying to drink the foam off the top of a glass of beer; you do a lot of drinking but don't get to swallow much, the same is true with your engine when the oil froths.
Keith

Keith

[K.Wilson]

Wes,
If the oil dip stick and dipstick tube are stock and mounted in the stock locations you should use the dip stick reading as the guide as to what the oil level should be; no more oil than the full mark and no less than the add mark with the engine off and at normal operating temp. It does not make any difference how many filters, oil coolers, feet of oil line, or size of oil pan you have, full equals full!

Now if the engine does not have the original equipment dip stick or tube or if they are in a different location that is another problem, and the dip stick must be calibrated to that engine.

Overfilling is just as bad as no oil at all. When over full, the oil can come into contact with the rotating crankshaft; this will cause the oil to "froth" or foam-up like laundry soap so the liquid oil level is decreased and there is nothing for the pump to pick up. Kind of like trying to drink the foam off the top of a glass of beer; you do a lot of drinking but don't get to swallow much, the same is true with your engine when the oil froths.
Keith

Keith

[souzape]

Wes- I've got to disagree with part of what Keith has said (repectfully). When you add external accessories to the engine you are increasing the volume which must be serviced by the oil. The original (stock) oil level is determined as Keith stated by ensuring that all the moving parts are lubricated and that there remains a sufficient amount of oil in the pan to keep the pick-up for the oil pump submerged so that it does not suck air. Have you ever noticed that when you change the oil and filter on your car you can get one reading on the dip stick after add the recommended amount of oil (It will indicate overfull) and then it goes down after you start it and distribute the oil through the engine and filter? The manufacturer takes this into consideration when the calibration marks on the dipstick are determined. But when you add more volume to the system (multiple oil filters, lines, coolers, etc.) that oil in the pan has to go fill more volume that the stock engine and the level remaining in the pan to cover the oil pick up may be less with the engine running. Granted, some oil may remain in that extra volume but if any is siphoned back into the pan from that extra volumn when you shut the engine down you can get a false perception. Obviously the best way to measure proper oil level would be with a sight gauge on the pan so that you could observe where the level is when the engine is running. A high volume oil pump can make this deception more noticable with the engine running. At issue is whether the stock (static) volumn of oil, indicated by the dipstick, is adequate after you change the total volumn of the oil system. Again, if you're not having problems with low or fluctuating pressure, you are probably OK. PHIL

[souzape]

Wes- I've got to disagree with part of what Keith has said (repectfully). When you add external accessories to the engine you are increasing the volume which must be serviced by the oil. The original (stock) oil level is determined as Keith stated by ensuring that all the moving parts are lubricated and that there remains a sufficient amount of oil in the pan to keep the pick-up for the oil pump submerged so that it does not suck air. Have you ever noticed that when you change the oil and filter on your car you can get one reading on the dip stick after add the recommended amount of oil (It will indicate overfull) and then it goes down after you start it and distribute the oil through the engine and filter? The manufacturer takes this into consideration when the calibration marks on the dipstick are determined. But when you add more volume to the system (multiple oil filters, lines, coolers, etc.) that oil in the pan has to go fill more volume that the stock engine and the level remaining in the pan to cover the oil pick up may be less with the engine running. Granted, some oil may remain in that extra volume but if any is siphoned back into the pan from that extra volumn when you shut the engine down you can get a false perception. Obviously the best way to measure proper oil level would be with a sight gauge on the pan so that you could observe where the level is when the engine is running. A high volume oil pump can make this deception more noticable with the engine running. At issue is whether the stock (static) volumn of oil, indicated by the dipstick, is adequate after you change the total volumn of the oil system. Again, if you're not having problems with low or fluctuating pressure, you are probably OK. PHIL

[WBofTN]

Thanks Guys - This info helps - my oil pressure seems
good (above 40 at idle and close to 60 at speed)
Phil: good luck on your issues - I know that guage can take the fun out of driving these things.
Wes

'93 Unique 427/351W/4sp

[WBofTN]

Thanks Guys - This info helps - my oil pressure seems
good (above 40 at idle and close to 60 at speed)
Phil: good luck on your issues - I know that guage can take the fun out of driving these things.
Wes

'93 Unique 427/351W/4sp

[souzape]

Wes, this got kind of spooky didn't it. Good luck to you too. PHIL

[souzape]

Wes, this got kind of spooky didn't it. Good luck to you too. PHIL

[K.Wilson]

Wes,
I do not disagree with Phil, however, unless the added components in the oil system reside significantly higher in the engine compartment than the oil pan there should be very little drainback into the pan. In my case the oil cooler is maybe only an inch or so above the oil level in the pan (they are both nearly the lowest level on the car).
A good way to establish how nuch of that "drain back" oil needs to be accounted for would be to run the engine to operating temp. then shut it off and within 30 seconds or so check the oil level on the dip stick and record the oil level, wait a half hour and check the oil level again. The difference would be the drain back and you could add that amount of oil to assure yourself the oil was at the correct level when the engine is running. My guess would be that the drain back oil will be less than 1/2 quart, (that is what it is in my big block with a 12 row oil cooler, two oil filters and eight feet of line).
Keith
Keith

[K.Wilson]

Wes,
I do not disagree with Phil, however, unless the added components in the oil system reside significantly higher in the engine compartment than the oil pan there should be very little drainback into the pan. In my case the oil cooler is maybe only an inch or so above the oil level in the pan (they are both nearly the lowest level on the car).
A good way to establish how nuch of that "drain back" oil needs to be accounted for would be to run the engine to operating temp. then shut it off and within 30 seconds or so check the oil level on the dip stick and record the oil level, wait a half hour and check the oil level again. The difference would be the drain back and you could add that amount of oil to assure yourself the oil was at the correct level when the engine is running. My guess would be that the drain back oil will be less than 1/2 quart, (that is what it is in my big block with a 12 row oil cooler, two oil filters and eight feet of line).
Keith
Keith

[WBofTN]

keith: my filters are mounted low on the front cross
member, so I agree the only drain back should be from the high points of the oil line. I will try your suggestion this weekend.
Phil:
Not spooked here - both you guys make good points.
At least neither of you said "just listen till you
hear knocking or tappet noises - then add a quart"
None of you commented on synthetic oil, Maybe a bigger
can of worms???
All I can say a/b synthetic is: Its Damn slippery stuff.
Wes

'93 Unique 427/351W/4sp