Any Ford techs on board?
 

I have an old car that I drive back and forth to work that has an issue. 2013 Taurus 3.5 with 65K miles on it. When warm and stopping at a stop light sometimes the low oil pressure warning lamp comes on. It goes off immediately after hitting the throttle. I have checked for TSB's and found nothing. The oil pressure sending unit was leaking through the center so I replaced it, no change. I dumped the 5w-20 and put in 5w-30 with no change. I have not hooked up a manual gauge to it yet, but I assume the oil pressure is dropping too low at idle. I did a google search for this problem and it seams that it happens a lot with the cars, suv's and pickups with the 3.5 engine, but no one has posted the fix for it that I can find. Is there a known problem with the oil pumps? Bearings" Cam timing actuators? Just looking for a place to start. Thanks

Im not a ford tech...but i just looked at the oil pump for your car on rock auto and see its crank driven like so many are these days. I had an issue with my 5.3 on my chevy...turns out the o-ring where the pickup tube tot he oil pump cracked and was letting oil pressure leak past. Guess its a common thing on the LS motors! Anyway it may be the issue you are dealing with as well. First ting i would do is hook up mech gauge and see what the actual oil psi is compared to gauge...it may be as simple as a bad calibration and just need a new sending unit....but if you are dropping the pan and removing the timing cover i'd change the oil pump while in there and get the upgraded oring for the pickup tube...

X2 on sending unit
cheap and easy enough to try and I have had a LOT of them read low over the years

Worn internal bearings will also indicate oil pressure under throttle and fall off the charts (hence your warning light) at idle - especially when the engine/oil is warm (less viscosity).

Start diagnosis with easy to determine senders and work up....

What oil filter are you using or do you use a fast lube service for oil changes? Have heard stories where the wrong filters are thrown on and pressure issues follow.....

First thing I did was change sending unit, it was leaking a little. I use Wix 7502 filters and Schaeffers synthetic oil. We have it at work in bulk. I know that i need to hook a mechanical gauge to it, I just haven't done it yet.

I had a weird synthetic oil experience last year when Costco came out with their Kirkland Brand. I figured they usually get the best on the market for their own stuff so why not. Up until this point i have used nothing but Mobil 1 Or Redline oils.
and my maint sched was to change the filter out (AC Delco) every 2500 miles and top off oil, but do a full oil change at 5000miles intervals. Anyway changed to the Kirkland brand and after about the 3500mile mark i got a low oil psi light....these engines are apparently known for clogging the sending unit screen and I've changed one out before shortly after buy the truck( It was used) so i got a new one and no difference.....changed sending unit...no difference....did a full oil change early with same oil...it went away. did the normal filter change again at 2500 and topped off and it again happened right around the 3500-4000mile mark! Low oil psi again! I don't know if the oil is breaking down or what but went back to Mobil1 and Redline and i don't have these issues anymore....weird. :confused:

I bought this car at a repo auction for about 5% of its actual value, so I can afford to put some money into it if need be. It does it immediately after an oil change, so it wouldn't be an oil breakdown issue. I believe the light comes on at 10psi and it is just dropping below that at hot idle. I am temped to just put some rotella in it and send it, but I don't mind fixing it. I just don't want to tear it down to put an oil pump and bearings in it if there are other known issues such as cam phasers leaking or piston squirters or something else. There are a ton of threads on this in the Ford forums, but no one seems to get theirs fixed.