It could be a bad oil pressure sending unit, Maybe. OEM oil pressure readings are: at normal operating temp. and at idle oil pressure gauge should read, 4.3 psi (or a little more), at 3000 rpm it should read 36 psi-71 psi. Idk why there is such a huge gap but that's what the TSRM says.
http://www.cygnusx1.net/supra/Librar...Section=LU&P=4
Also, get some degreaser and clean the bottom of the car with pressure hose and get a mechanic or somebody knowledgeable about cars to get them to try and find the oil leak, if it's only a quart every month or so you are fine. But 7mgte's are no good with low oil pressure cuz something bad will happen to the engine.
Is it the stock oil pressure gauge or aftermarket?
BTW you have a 7mge or 7mgte cuz I think the readings are meant for both engines but I'm no expert so do more research. Or maybe CRE or somebody more knowledgeable will chime in for ya.