Question on Checking Oil

Hi:

I feel silly for asking this question but I am having a really difficult time trying to get an accurate check on the oil level in the Roush 427 SR in my Superformance GT40 MKII. The car has the standard Superformance oil cooler, and after driving the car and letting it sit overnight the oil level will be WAY above the full mark on the dipstick. Then, I will wipe the dipstick and recheck it and the oil level will be way down---just above the add mark, BUT if I wait awhile and/or do several re-checks the level will be up a bit more. Also, if after doing all this and letting it sit a few days it will rise to the full mark or just be above. I have also tried the technique of running the car, shutting it off, waiting for about a half an hour and rechecking. I will usually get a reading somewhere between the ADD and FULL lines, but it varies substantially. I attribute some of this behavior to the oil cooler perhaps draining back into the crankcase, but thought I would check to see if anyone had a similar problem or suggestions.

Thanks!
/s/ Chris Kennedy
 
Is the car level? You should get an accurate reading hot or cold. Understandably Oil travels to oil cooler etc, etc.. But let the experts answer this one, I'm just an owner of a MKII but this is what I do and reads perfect. If you let it sit overnight, the first reading discard, wipe off and re-insert dipstick and see. My .02. Or after running it, wait a bit and check, you don't want it cold again. If you're getting low reading when hot, the oil pump is also right there, you want that fed well at all times hot & cold.
 

Dave Hood

Lifetime Supporter
Is this a new engine? If so, you might contact Roush. I've repositioned my oil cooler but had the standard Superformance version for about 7 years and never had that issue.
 

Bill Kearley

Supporter
The accurate check is to pull the dip stick on a cold engine once. That's it. If you start pulling it in and out every thing gets wet if you know what I mean !! and gives false readings. I don't know your car with respect to a chance of the cooler drain back. No check valves? It's not hard to estimate the oil content of the cooler and lines then add to the specified amount. Done.
 
Thank you, everyone, for your thoughts and suggestions. The engine is original to the car and has a little under 4,000 miles on it. I spoke with Roush awhile back and they recommended the run, shut off, and check about 30 minutes later method of checking. I am a lifelong fan of the sit overnight method, myself, but in this car it has lead to wild and not altogether predictable variances. What I plan to do is go back and rethink everything and take it from there. Again, thanks for the replies!

/s/ Chris
 
I would think, the oil system would have an anti drainback to prevent this from happening.
Not all oil filters have a decent anti drainback valve. (Ford FL-1A & Wix 51515 do have).

I never have experianced this issue with any drainback after a while in all my cars. Not even in my GT40 with remote oilfilter & oilcooler above sump level.
Not even in my dragrace car, Ford Capri supercharged V8 with remote oil filter & cooler above sump level. Not even in my GP2 Capri with the same setup.

I only use Wix 51515 or Ford FL-1A or Ford EFL-90 filters (same as Mahle OC-23) oil filters. Depemts if I have room for the big filter or not.
 
Thanks for the reply. Actually, I use the Wix filter. I have told people that I have had to "rejigger" a lot of my thinking about cars and driving when I discuss this car, especially since I use it in the real world (I live in San Diego, and drove out to the California desert east of here with it a few weeks ago, and like exploring side roads off of Interstate 8 with the car). I will figure it out.

/s/ Chris
 

Randy V

Moderator-Admin
Staff member
Admin
Lifetime Supporter
Basically speaking, you only truly need enough oil to cover the oil pump pickup at all times. Having a couple of extra quarts only buys you some time as a buffer in case you are experiencing higher than normal G-Forces or have a leak. I've often times challenged myself and others to justify carrying 15 quarts of oil in the sump of a Ford/Dodge/Chevy Diesel Pickup truck. Since oil dillution on the newer trucks is not nearly as pervasive of a problem as it was to the old mechanical injection engines, that is not much of a justification. Of course all of this is taking filters, coolers, lines etc. into consideration..
 

Howard Jones

Supporter
Does your oil cooler system, cooler, and lines, drain when the engine is not running. Meaning is the in/out of the oil cooler on the bottom or side so that gravity will attempt to cause the oil to drain downhill into the sump through the filter. Filters vary in anti-drain-back efficiency.

Note: I would plumb the cooler if it is on its side so that the bottom line goes back to the engine (cool oil or pressure side). This will help keep the cooler primed. If it's arranged the other way around then the oil will try and flow back to the sump through the filter. This can be a slow process but it will still drain, how fast is dependant on filter quality. If the cooler has the in/out on the bottom then the orientation of the lines is of no consequence and the cooler will not remain primed beyond the ability of the filter to prevent drain back. I think the best way is to mount coolers with the in/out on top to retain a primed condition or low in the car to avoid gravity drain back altogether. This isn't too much of a concern if the driver will remember to crank it around until oil pressure comes up before turning on the ignition.

If the cooler in/out is on top then of course its volume of oil remains in it when the engine is not running.

Note on cooler install: cooler is inline AFTER the filter. Like this in order. sump > pump > filter >cooler > back to engine pressure gallery to bearings/lifters/ valve train etc > then drains back to the sump.

Now that we have established that. The next time you drain the oil: Let it completely drain until it stops dripping. This may well be several hours. Replace the filter with a new empty one. Now you have a system with very little oil in it unless the cooler is an "up" type. In this case, you will always have its volume in it and it does not factor into the following anyway other than it needs to be accounted for.

Let's assume the engine builder says it should be full at 7 quarts with the filter full of oil. So now with a dry filter installed on the motor put in 6 quarts, leave out the dipstick, and crank over the motor (ign off) until you have normal cold oil pressure. Now let it drain back for a couple of hours. The level on the dipstick is your 6-quart level less the cooler volume but isn't what you need to mark on the dipstick. You still need to account for the cooler system volume.

If it is a "bottom/side" type cooler the oil has drained back into the sump and its volume will need to be added to account for the cooler when the engine is running. If you have a "top" type then you still need to add the cooler volume to replace the oil now trapped in the cooler.

You will need to look up the manufacture of the cooler and ask how much it holds (information may be in the catalog) or take it off and fill it and its lines with oil to get a volume. Add that amount to your 6-quart fill and install dipstick. This is your 1-quart low mark.

Add the final quart, again give it time to drain down into the sump as before and check your level on the dipstick for the final time and mark it as full.

Don't worry about overfilling when it's not running. My guess is, it's about another quart or less in the cooler and lines and that won't hurt anything on startup or some sort of an overfilled caused leak otherwise.
 
Last edited:

Ian Anderson

Lifetime Supporter
Supporter
Probably a daft question. Is your dip stick always returning to the same spot? Is the dip stick tube / locator fitted so it cannot move ( I have seen some move on various engine makes) which means the dipstick ends up at varying heights in relation to the bottom of the sump, oil level may be fine but the way your reading is being taken causes the apparent variance?

Ian
 
Does your oil cooler system, cooler, and lines, drain when the engine is not running. Meaning is the in/out of the oil cooler on the bottom or side so that gravity will attempt to cause the oil to drain downhill into the sump through the filter. Filters vary in anti-drain-back efficiency.

Note: I would plumb the cooler if it is on its side so that the bottom line goes back to the engine (cool oil or pressure side). This will help keep the cooler primed. If it's arranged the other way around then the oil will try and flow back to the sump through the filter. This can be a slow process but it will still drain, how fast is dependant on filter quality. If the cooler has the in/out on the bottom then the orientation of the lines is of no consequence and the cooler will not remain primed beyond the ability of the filter to prevent drain back. I think the best way is to mount coolers with the in/out on top to retain a primed condition or low in the car to avoid gravity drain back altogether. This isn't too much of a concern if the driver will remember to crank it around until oil pressure comes up before turning on the ignition.

If the cooler in/out is on top then of course its volume of oil remains in it when the engine is not running.

Note on cooler install: cooler is inline AFTER the filter. Like this in order. sump > pump > filter >cooler > back to engine pressure gallery to bearings/lifters/ valve train etc > then drains back to the sump.

Now that we have established that. The next time you drain the oil: Let it completely drain until it stops dripping. This may well be several hours. Replace the filter with a new empty one. Now you have a system with very little oil in it unless the cooler is an "up" type. In this case, you will always have its volume in it and it does not factor into the following anyway other than it needs to be accounted for.

Let's assume the engine builder says it should be full at 7 quarts with the filter full of oil. So now with a dry filter installed on the motor put in 6 quarts, leave out the dipstick, and crank over the motor (ign off) until you have normal cold oil pressure. Now let it drain back for a couple of hours. The level on the dipstick is your 6-quart level less the cooler volume but isn't what you need to mark on the dipstick. You still need to account for the cooler system volume.

If it is a "bottom/side" type cooler the oil has drained back into the sump and its volume will need to be added to account for the cooler when the engine is running. If you have a "top" type then you still need to add the cooler volume to replace the oil now trapped in the cooler.

You will need to look up the manufacture of the cooler and ask how much it holds (information may be in the catalog) or take it off and fill it and its lines with oil to get a volume. Add that amount to your 6-quart fill and install dipstick. This is your 1-quart low mark.

Add the final quart, again give it time to drain down into the sump as before and check your level on the dipstick for the final time and mark it as full.

Don't worry about overfilling when it's not running. My guess is, it's about another quart or less in the cooler and lines and that won't hurt anything on startup or some sort of an overfilled caused leak otherwise.
Hi, and thank you very much for all your observations and suggestions. Basically, the oil cooler is the standard one that comes with a Superformance car and appears to be plumbed in at the bottom (I will see what detailed info I can get on the cooler---once again my repeated request to Superformance to produce a service manual makes sense) . The engine has a sump capacity of 8 qts., and I estimate cooler and line capacity to be about 1 to 1.5 qts. based upon talking with Roush and experience in oil changes to date. What's really odd to me is that after shutdown and overnight the oil level is WAY above full (probably three to four inches, above, maybe more when you first remove the stick--I attribute this to drain back from the cooler but this much??), then you wipe the stick and reinsert, and it is somewhere between ADD and FULL, then you let it sit for a few days and you are slightly above full. I know that with other cars I have gotten some variation between letting it sit, the first wipe of the stick and the reinsert and re-sticks thereafter), but never this much. As I mentioned, I will get to the bottom of it and report. Again, your reply was above and beyond the call of duty, and I owe you one!

Regards,

/s/ Chris
 
Probably a daft question. Is your dip stick always returning to the same spot? Is the dip stick tube / locator fitted so it cannot move ( I have seen some move on various engine makes) which means the dipstick ends up at varying heights in relation to the bottom of the sump, oil level may be fine but the way your reading is being taken causes the apparent variance?

Ian
Thank you, Sir, for your reply----no question on these cars is daft! As I mentioned previously, I have had to re-jigger all my thinking about cars with respect to this car and to assume nothing and always check the basics. To answer your question, I have checked and the stick and tube are properly anchored and not moving around.

Regards,
/s/ Chris
 
I've got an identical setup to you ( SPF MKII Roush 427SR). Yes level varies from shutdown to next day. Overnight drainage from the big aircraft cooler is the biggest factor. However I never get the level up several inches on the dipstick. Usually all within the add to full marks which is about 1 qt.
I rely on level overnight from shutdown. Your total capacity numbers are about right.
 
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