Joe I believe that you have your EIS warning set too high for the engine. 28 psi is good oil pressure, and is about double what most late model GM engines show as their oil pressure once they are hot. A good rule of thumb for pressure is 10 psi for every 1000 rpms. A normal engine will have high oil pressure cold and then "lose" 10 -20 psi once it is hot, as clearances increase.
You say you have no leaks. If you also do not have an associated increase in engine noise, and the oil pressure does not continue to reduce, but rather consistently holds these new numbers, I would say that your engine just finally broke in, and the bearings and such seated. With those numbers you have plenty of pressure to handle loads. My concern would always be once pressure is established, is circulation. Too much oil pressure pumps all the oil to the top of the system, and robs the oil pan area of needed splash oil. I have built engines for 15 years, and all my engines new would have 60 to 80 psi cold, and drop to 45 to 50 psi at cruise rpm, and 20 to 35 psi at idle (depending on idle rpm) once the engine was hot and broken in. Thick oils will give the illusion of better oil system due to higher indicated pressure, but tend to thicken too soon, except in the hottest engines and will not circulate as well. Modern engines use 5W30 which is like water in viscosity because designers have found that good circulation is more important than high indicated pressure. I am not advocating using 5W30, but oil quality has increased dramatically over the last 15 years. I would never run 100W Aeroshell in my Corvair just because it is an aviation recommended oil, because it does not match my engine. It is WAY too thick and will cause major problems with circulation, and drastically increase the wear on my engine. Depending on temps and use I will be running 10W30 to 10W40 heavy duty oil, and will break my engine in on straight 30HD oil (first two hours, then fresh oil and filter for flight). Read the Corvair engine assembly manual and it will detail the same recommendations. As always your results may vary... Colin N96TA
