spend $10 and try a bottle Lucas oil additive
Most of the snake oil products out there are just that
I have seen tons of positive results (I sold Lucas to garages for years)

I originally got turned on to it by their rep giving me a bottle of the P.S product for my old plow truck
The P.S leaked terribly
I never ever got the entire bottle in before the leak stopped
I used the truck for another 10 yrs without issue

 

well lately i had noticed its doing the pressure drop almost like it was when towing, except im not. had about 3,000 miles on the last oil change, did have to add a qt at about 2,500. today i changed the sender for the guage and changed the oil. now when i hit resume it keeps a constant pressure reading on the guage (like it should) i even tried driving it hard to see if i could get the pressure drop to happen, it didnt...not sure if its the fresh oil, the sender i just installed or maybe a bit of both. used the same oil/filter as the last time, pennzoil 5w30, purolator "gold can" filter. oil was kind of dark, but with over 200K on this engine, i would imagine its got some blow-by going on. not easy to change the sender with the distributor in place-but possible. hopefully its cured now, very troubling to be driving and watch the pressure drop like it was. lifters never made that "low oil" noise though, so i doubt it really lost pressure like it was saying it was.